DATE OF LEASE EXECUTION: 5/2l/98

                                    ARTICLE I
                                 REFERENCE DATA

1.1 SUBJECTS REFERRED TO:

     Each reference in this Lease to any of the following subjects shall be
construed to incorporate the data stated for that subject in this Section 1.1:

LANDLORD:

         CambridgePark Two Limited Partnership

MANAGING AGENT:

         Spaulding and Slye Services Limited Partnership

LANDLORD'S & MANAGING AGENT'S ADDRESS:

         Spaulding and Slye Services Limited Partnership
         125 CambridgePark Drive
         Cambridge, MA 02140

LANDLORD'S REPRESENTATIVE:

         John M. Kane

TENANT:

     Allaire Corporation, a corporation organized under the laws of the State of
Massachusetts.

TENANT'S ADDRESS (FOR NOTICE AND BILLING):

         Allaire Corporation
         150 CambridgePark Drive
         Cambridge, MA 02140

TENANT'S REPRESENTATIVE:

         David Gerth, CFO

PREMISES:

         The space located on the 3rd floor of the Building as shown on
         Exhibit B-1 and the space located on the 2nd floor of the
         Building as shown on Exhibit B-2.

RENTABLE FLOOR AREA OF THE PREMISES:

         approximately 32,499 square feet, consisting of approximately
         24,554 square feet on the 3rd floor (the "Third Floor
         Premises") and 7,945 square feet on the 2nd floor (the "Second
         Floor Premises").


                                       1



TOTAL RENTABLE FLOOR AREA OF THE BUILDING:

         approximately 252,180 square feet

SCHEDULED TERM COMMENCEMENT DATE:

         September 1, 1998 with respect to the Second Floor Premises
         and November 1, 1998 with respect to the Third Floor Premises.

LEASE TERM OR TERM:

         Commencing on the Term Commencement Date as defined in Section
         3.1 hereof and continuing for five (5) years and four (4)
         months thereafter, plus the partial month at the beginning of
         the Term, if any, unless sooner terminated as provided herein

ANNUAL RENT:

         $30.00 per square foot of Rentable Floor Area of the Premises,
         or $81,247.50 per calendar month, and proportionally at such
         rate for any partial month (net of Tenant's charges for
         electrical consumption in the Premises).

RENT COMMENCEMENT DATE FOR THIRD FLOOR PREMISES:

         The later of (a) January 1, 1999, and (b) sixty days after
         Landlord delivers the Third Floor Premises to Tenant in
         accordance with Section 3.2; provided, however, if Tenant
         shall be delayed in obtaining a Certificate of Occupancy for
         the Third Floor Premises within such sixty (60) day period due
         to the fault of Landlord, then the Rent Commencement Date
         shall be delayed for an equivalent period of time.

BASE ANNUAL ELECTRICITY CHARGE:

         $ 1.00 per square foot of Rentable Floor Area of the Premises

BASE ANNUAL OPERATING COSTS:

         $9.00 per square foot of Rentable Floor Area of the Premises

TENANT'S PROPORTIONATE SHARE:

         Until the Rent Commencement Date for the Third Floor Premises,
         3.15 percent, and thereafter, 12.89 percent, subject to
         adjustment based upon changes in the rentable floor area of
         the Building or the Premises.


                                       2



PERMITTED USES:

         Office Uses

COMMERCIAL GENERAL LIABILITY INSURANCE:

         $1,000,000 bodily injury, property damage combined single
         limit per occurrence, $2,000,000 annual aggregate.

BROKER:
         Spaulding and Slye Services Limited Partnership

SECURITY DEPOSIT:

         $487,485.00, or the amount of the Tenant Improvement Allowance
         used by Tenant, as the same may be further reduced pursuant to
         Article XI.

GUARANTOR:

         None

TENANT'S PARKING ACCESS CARDS:

         3 parking access cards per 1000 square feet or 97 parking
         access cards.

TENANT IMPROVEMENT ALLOWANCE:

         $15.00 per square foot of Rentable Floor Area of the Premises or
         $487,485.00.

1.2 EXHIBITS.

         The exhibits listed below in this section are incorporated in this
Lease by reference and are to be construed as part of this Lease:

        EXHIBIT A                   Description of Lot
        EXHIBIT B-1                 Plan showing Third Floor Premises
        EXHIBIT B-2                 Plan showing Second Floor Premises
        EXHIBIT C                   (Intentionally Omitted)
        EXHIBIT D                   Landlord's Services
        EXHIBIT E                   Rules and Regulations
        EXHIBIT F                   Building Standards


                                       3





                                TABLE OF CONTENTS


                                                                                                   

ARTICLE II                                                                                            Page
  PREMISES AND TERM......................................................................................7
  2.1    DESCRIPTION OF PREMISES.........................................................................7
  2.2    TERM............................................................................................7
  2.3    OPTION TO EXTEND................................................................................7

ARTICLE III
  CONSTRUCTION...........................................................................................9
  3.1    TERM COMMENCEMENT DATE..........................................................................9
  3.2    DELIVERY OF PREMISES ...........................................................................9
  3.3    PREPARATION OF PREMISES FOR OCCUPANCY .........................................................11
  3.4    GENERAL PROVISIONS APPLICABLE TO CONSTRUCTION..................................................12
  3.5    ALTERATIONS AND ADDITIONS......................................................................12
  3.6    REPRESENTATIVES................................................................................14

ARTICLE IV
  RENT..................................................................................................14
  4.1   ANNUAL RENT ....................................................................................14
  4.2   ANNUAL OPERATING COST ESCALATION ...............................................................14
  4.3   ESTIMATED ANNUAL OPERATING EXPENSE ESCALATION PAYMENT...........................................17
  4.4   ELECTRICITY.....................................................................................18
  4.5   CHANGE OF FISCAL YEAR...........................................................................19
  4.6   PAYMENTS........................................................................................19

ARTICLE V
  LANDLORD'S COVENANTS..................................................................................20
  5.1    LANDLORD'S COVENANTS DURING THE TERM...........................................................20
         5.1.1  Building Services.......................................................................20
         5.1.2  Additional Building Services............................................................20
         5.1.3  Repairs.................................................................................20
         5.1.4  Tenant Directory........................................................................20
         5.1.5  Food Service............................................................................20
         5.1.6  Quiet Enjoyment.........................................................................21
         5.1.7  Tenant's Costs..........................................................................22
  5.2    INTERRUPTIONS..................................................................................22

ARTICLE VI
  TENANT'S COVENANTS....................................................................................23
  6.1    TENANT'S COVENANTS DURING THE TERM.............................................................23


                                        4






        6.1.1  Tenant's Payments........................................................................23
        6.1.2  Repairs and Yielding Up..................................................................23
        6.1.3  Occupancy and Use........................................................................23
        6.1.4  Rules and Regulations ...................................................................24
        6.1.5  Safety Appliances........................................................................24
        6.1.6  Assignment and Subletting................................................................25
        6.1.7  Indemnity................................................................................26
        6.1.8  Tenant's Insurance ......................................................................26
        6.1.9  Tenant's Worker's Compensation Insurance.................................................26
        6.1.10 Landlord's Right of Entry................................................................27
        6.1.11 Loading .................................................................................27
        6.1.12 Landlord's Costs.........................................................................28
        6.1.13 Tenant's Property........................................................................28
        6.1.14 Labor or Materialmen's Liens.............................................................28
        6.1.15 Changes or Additions.....................................................................28
        6.1.16 Holdover.................................................................................28
        6.1.17 Security.................................................................................29
        6.1.18 Tenant Financial Statements..............................................................29

ARTICLE VII
  DAMAGE AND DESTRUCTION; CONDEMNATION..................................................................29
  7.1   FIRE OR OTHER CASUALTY..........................................................................29
  7.2   EMINENT DOMAIN..................................................................................31

ARTICLE VIII
  RIGHTS OF MORTGAGEE...................................................................................32
  8.1    PRIORITY OF LEASE..............................................................................32
  8.2    RIGHTS OF MORTGAGE HOLDERS; LIMITATION OF MORTGAGEE'S LIABILITY................................33
  8.3    MORTGAGEE'S ELECTION...........................................................................34
  8.4    NO PREPAYMENT OR MODIFICATION, ETC.............................................................34
  8.5    NO RELEASE OR TERMINATION......................................................................34
  8.6    CONTINUING OFFER...............................................................................35

ARTICLE IX
  DEFAULT...............................................................................................35
  9.1   EVENTS OF DEFAULT ..............................................................................35
  9.2   TENANT'S OBLIGATIONS AFTER TERMINATION..........................................................36

ARTICLE X
  MISCELLANEOUS.........................................................................................37
  10.1 NOTICE OF LEASE..................................................................................37
  10.2 RELOCATION ......................................................................................38
  10.3 NOTICES FROM ONE PARTY TO THE OTHER..............................................................38


                                       5





  10.4  BIND AND INURE..................................................................................38
  10.5  NO SURRENDER ...................................................................................39
  10.6  NO WAIVER, ETC..................................................................................39
  10.7  NO ACCORD AND SATISFACTION......................................................................39
  10.8  CUMULATIVE REMEDIES ............................................................................39
  10.9  LANDLORD'S RIGHT TO CURE .......................................................................40
  10.10 ESTOPPEL CERTIFICATE ...........................................................................40
  10.11 WAIVER OF SUBROGATION ..........................................................................40
  10.12 ACTS OF GOD.....................................................................................41
  10.13 BROKERAGE.......................................................................................41
  10.14 SUBMISSION NOT AN OFFER.........................................................................41
  10.15 APPLICABLE LAW AND CONSTRUCTION.................................................................41
  10.16 AUTHORITY OF TENANT.............................................................................42

ARTICLE XI
  SECURITY DEPOSIT......................................................................................42



                                        6



                                   ARTICLE II
                                PREMISES AND TERM

2.1      DESCRIPTION OF PREMISES.

     Subject to and with the benefit of the provisions of this Lease, Landlord
hereby leases to Tenant, and Tenant leases from Landlord, the Premises described
in Section 1.1 excluding exterior faces of exterior walls, the common facilities
area and building service fixtures and equipment serving exclusively or in
common other parts of the Building.

     Tenant shall have, as appurtenant to the Premises, the right to use in
common with others entitled thereto: (a) common walkways, driveways, hallways,
lobbies, ramps, loading docks and stairways located in the Building or on the
parcel on which the Building is located (the "Lot"), (b) building service
fixtures and equipment serving the Premises including elevators, (c) the parking
facility, if any, on a first-come, first-served basis in the location from time
to time designated by Landlord, Tenant's use not to exceed the number of
Tenant's Parking Access Cards, and (d) if the Premises include less than the
entire Rentable Floor Area of any floor, the common toilets in the central core
area of such floor. Such rights shall be always subject to the Rules and
Regulations set forth in Exhibit E, attached hereto and incorporated herein by
reference, as the same may be amended by the Landlord from time to time and such
other reasonable Rules and Regulations from time to time established by the
Landlord by suitable notice to Tenant which such Rules and Regulations and
amendments thereto shall be uniformly applied to all tenants and occupants of
the Building, and to the right of the Landlord to designate and change from time
to time such areas, facilities, fixtures and equipment.

2.2 TERM.

     To have and to hold for a period (the "Term") commencing on the Term
Commencement Date (as defined in Section 3.1 hereof) and continuing for the
Term, unless sooner terminated as provided herein.

2.3 OPTION TO EXTEND.

     Tenant shall have the right and option to extend the Term for one (1)
additional period of five (5) years (the "Extension Term") commencing upon the
expiration of the original Term referred to in Section 1.1 (the "Original
Term"), provided that Tenant shall give Landlord notice of Tenant's exercise of
such option at least twelve (12) months prior to the expiration of the Original
Term and provided further that no event of default by Tenant exists hereunder,
and no condition exists which with the giving of notice or the passage of time,
or both, would constitute an event of default hereunder unless the same is cured
within the applicable cure


                                        7



period, at either the time of giving such notice or at the time of the
commencement of such Extension Term. Prior to the exercise by Tenant of such
option, the expression "Term" shall mean the Original Term, and after the
exercise by Tenant of such option, the expression "Term" shall mean the Original
Term as it has been extended by the Extension Term. Except as expressly
otherwise provided in the following paragraph and except for this Section 2.3
hereof, all the terms, covenants, conditions, provisions and agreements in the
Lease contained shall be applicable to the Extension Term. If Tenant shall give
notice of its exercise of said option to extend in the manner and within the
time period provided aforesaid, the Term shall be extended upon the giving of
such notice without the requirement of any further action on the part of either
Landlord or Tenant. If Tenant shall fail to give timely notice of the exercise
of any such option as aforesaid, Tenant shall have no right to extend the Term
of this Lease, time being of the essence of the foregoing provisions.

     The Annual Base Rent payable during the Extension Term shall be the amount
being the greater of (i) the Annual Base Rent in effect for the Lease Year
immediately preceding the commencement of the Extension Term or (ii) the Fair
Market Rent for the Premises, as determined below, as of the commencement of the
Extension Term. If for any reason the Annual Base Rent payable during the
Extension Term has not been determined as of the commencement of the Extension
Term, Tenant shall pay the Annual Base Rent payable during the Original Term
until the Annual Base Rent for the Extension Term is determined, at which time,
an appropriate adjustment, if any, shall be made.

     For purposes here, the Fair Market Rent shall mean the fair rent for the
Premises as of the commencement of the Extension Term under market conditions
then existing. Fair Market Rent shall be determined by agreement between
Landlord and Tenant, but if Landlord and Tenant are unable to agree upon the
Fair Market Rent at least six (6) months prior to the date upon which the Fair
Market Rent is to take effect, then the Fair Market Rent shall be determined by
appraisal made as hereinafter provided by a board of three (3) reputable
independent commercial real estate consultants, appraisers, or brokers, each of
whom shall have at least ten years of experience in the north suburban Boston
office rental market and each of whom is hereinafter referred to as "appraiser".
Tenant and Landlord shall each appoint one such appraiser and the two appraisers
so appointed shall appoint the third appraiser. The cost and expenses of each
appraiser appointed separately by Tenant and Landlord shall be borne by the
party who appointed the appraiser. The cost and expenses of the third appraiser
shall be shared equally by Tenant and Landlord. Landlord and Tenant shall
appoint their respective appraisers at lease five (5) months prior to
commencement of the period for which Fair Market Rent is to be determined and
shall designate the appraisers so appointed by notice to the other party. The
two (2) appraisers so appointed and designated shall appoint the third appraiser
at lease four (4) months prior to the commencement of such period and shall
designate such appraisers by notice to Landlord and Tenant. The board of three
(3) appraisers shall


                                        8



determine the Fair Market Rent of the space in question as of the commencement
of the period to which the Fair Market Rent shall apply and shall notify
Landlord and Tenant of their determinations at least sixty (60) days prior to
the commencement of such period. If the determinations of the Fair Market Rent
of any two (2) or all three (3) appraisers shall be identical in amount, said
amount shall be deemed to be the Fair Market Rent of the subject space. If the
determinations of all three (3) appraisers shall be different in the amount, the
average of the two values nearest in amount shall be deemed the Fair Market
Rent. The Fair Market Rent of the subject space determined in accordance with
the provisions of this Section shall be binding and conclusive on Tenant and
Landlord.

                                   ARTICLE III
                                  CONSTRUCTION

3.1 TERM COMMENCEMENT DATE.

     The Term of this Lease shall commence on, and the Term Commencement Date
shall be, the earlier of the Term Commencement Date for the Second Floor
Premises or the Term Commencement Date for the Third Floor Premises. For each of
the Second Floor Premises and the Third Floor Premises, the Term Commencement
Date therefor shall be the earlier of (a) the applicable Scheduled Term
Commencement Date or (b) the date on which Tenant commences beneficial use
thereof for its business purposes; provided, however, that if the date on which
Tenant commences to occupy the Premises is delayed beyond the Scheduled Term
Commencement Date due to the fault of Landlord, the Term Commencement Date shall
be delayed for an equivalent period of time.

     As soon as may be convenient after the Term Commencement Date has been
determined, at the request of either party, Landlord and Tenant agree to join
with each other in the execution, in recordable form, of a written Declaration
in which the Term Commencement Date and specified term of this Lease shall be
stated.

3.2 DELIVERY OF PREMISES.

     Landlord agrees to use reasonable and diligent efforts to deliver the
Second Floor Premises to Tenant free of all occupants and personal property on
or before September 1, 1998 and the Third Floor Premises to the Tenant free of
all occupants and personal property on or before November 1, 1998. Any delay in
such delivery shall result in a proportionate reduction in the Annual Rent and
additional rent due under this Lease on a day-to-day basis for each day of such
delay. In addition, Landlord agrees to give Tenant, its architect, the
Contractor (as defined below), and subcontractors reasonable access to the
Premises to permit Tenant to prepare drawings and obtain permits and approvals
with respect to Tenant's Work (as defined below). Notwithstanding the foregoing,
(a) if Landlord is unable to deliver the Second Floor Premises to Tenant free of
all occupants and personal property on or before May 1, 1999, Tenant shall have
the option to terminate this Lease with


                                        9



respect to the Second Floor Premises only by written notice to Landlord given on
or before June 1, 1999, and (b) if Landlord is unable to deliver the Third Floor
Premises to Tenant free of all occupants and personal property on or before July
1, 1999, Tenant shall have the option to terminate this Lease with respect to
the Third Floor Premises only by written notice to Landlord given on or before
August 1, 1999. In the event of termination as aforesaid, the parties shall have
no further liability each to the other with respect to the Second Floor Premises
or the Third Floor Premises, as applicable, and the provisions of Section 1.1
hereof shall be deemed amended to reflect the deletion of the applicable portion
of the Premises, including, without limitation, an appropriate pro rata
adjustment in Annual Rent and Tenant's Proportionate Share.

     Tenant acknowledges that Tenant has had an opportunity to inspect the
Premises. Except as set forth hereinafter, the Premises, shall be delivered to
Tenant As Is, Where Is with all faults and without representation, warranty or
guaranty of any kind by Landlord to Tenant. Notwithstanding the foregoing,
Landlord represents and warrants that the Premises and the base Building systems
serving the Premises are in good working order and condition.

     Subject to the provisions hereof, Tenant shall undertake all work to
prepare the Premises for Tenant's use and occupancy in accordance with Plans
approved as set forth below ("Tenant's Work") at Tenant's sole cost and expense,
except that Landlord shall reimburse Tenant in an amount not to exceed the
Tenant Improvement Allowance. Provided that Tenant is not then in default under
any provision of this Lease or, if Tenant is in default, that Tenant cures the
same within the applicable cure period, if any, the Tenant Improvement Allowance
shall be payable by Landlord to Tenant to reimburse Tenant for architectural
fees payable to Tenant's architect, Design Science (the "Architect"), upon
notice to Tenant accompanied by the Architect's invoice therefor and to pay the
Contractor (as defined hereinafter) directly upon notice to Landlord from time
to time, accompanied by invoices from the Contractor which have been approved by
the Architect. After the entire amount of the Tenant Improvement Allowance has
been paid out by Landlord, Tenant shall bear all additional costs to complete
Tenant's Work at Tenant's sole cost and expense. If any portion of the Tenant
Improvement Allowance remains after the completion of Tenant's Work, it shall
not be payable or credited to Tenant in any manner whatsoever. Tenant shall
retain Spaulding and Slye Construction Company (the "Contractor") to serve as
Tenant's general contractor; provided that the total cost to be charged by the
Contractor is competitive with bids by other qualified general contractors and,
provided, further, that all subcontracts are competitively bid. It is understood
and agreed that the actions or inactions of the Contractor shall in no way be
attributable to the Landlord, and that Landlord has no responsibility for the
completion of Tenant's Work.


                                       10



     For purposes hereof, Tenant shall submit a complete set of proposed plans
and specifications (collectively, "Plans") showing Tenant's Work to Landlord. No
later than fourteen (14) days thereafter, Landlord shall either approve or
disapprove the Plans, specifying by notice to Tenant in reasonable detail the
respects in which the Plans are disapproved. If Landlord disapproves the Plans,
Tenant shall submit to Landlord revised Plans which respond to the items of
disapproval specified in Landlord's notice no later than fourteen (14) days from
Landlord's notice of disapproval. Thereafter, Landlord shall have seven (7) days
from Tenant's submission of the Plans to Landlord to approve or disapprove the
revised Plans in accordance with the foregoing and, in case of disapproval,
Tenant shall have an additional seven (7) days to submit revised Plans
responding to the items of disapproval specified in Landlord's notices. The
parties shall work diligently and in good faith to agree upon approved Plans.

     Landlord will not approve any construction, alterations, or additions
requiring unusual expense to readapt the Premises to normal office use on lease
termination or increasing the cost of construction, insurance or taxes on the
Building or of Landlord's services called for by Section 5.1 unless Tenant first
gives assurances acceptable to Landlord that such readaptation will be made
prior to such termination without expense to Landlord and makes provisions
acceptable to Landlord for payment of such increased cost. Landlord will also
disapprove any alterations or additions requested by Tenant which will delay
completion of the Premises. Tenant's construction, installation of furnishings,
and later changes or additions shall be coordinated with any work being
performed by Landlord in such manner as to maintain harmonious labor relations
and not to damage the Building or Lot or interfere with Building operations.

3.3 PREPARATION OF PREMISES FOR OCCUPANCY.

     Landlord agrees to use reasonable efforts to substantially complete
Landlord's Work, if any, no later than the Scheduled Term Commencement Date,
subject to delays beyond Landlord's reasonable control and delays caused by
Tenant. Landlord shall be responsible for complying with all legal requirements
with respect to the common areas of the Building (including, without limitation,
the American with Disabilities Act) which shall be necessary for Tenant to
obtain a Certificate of Occupancy with respect to the Premises. The Premises
shall be deemed ready for occupancy on the date on which Landlord's Work is
substantially completed as certified by Landlord's architect, with the exception
of minor items which can be fully completed without material interference with
Tenant and other items which because of the season or weather or the nature of
the item are not practicable to do at the time, provided that none of said items
is necessary to make the Premises tenantable for the Permitted Uses; provided,
however, that if Landlord is unable to complete construction due to delay in
Tenant's compliance with any of the provisions hereof or


                                       11



due to other delays caused by Tenant (including, without limitation, any changes
to Landlord's Work requested by Tenant), then the Premises shall be deemed ready
for occupancy no later than the Scheduled Term Commencement Date.

3.4 GENERAL PROVISIONS APPLICABLE TO CONSTRUCTION.

     All construction work required or permitted by this Lease, whether by
Landlord or by Tenant, shall be done in a good and workmanlike manner and in
compliance with all applicable laws and all lawful ordinances, regulations and
orders of governmental authority and insurers of the Building and the Lot.
Either party may inspect the work of the other at reasonable times and promptly
shall give notice of observed defects. Landlord's obligations under Sections 3.2
and 3.3, if any, shall be deemed to have been performed when Tenant commences to
occupy any portion of the Premises for the Permitted Uses except for items which
are incomplete or do not conform with the requirements of Section 3.1 and as to
which Tenant shall in either case have given written notice to Landlord within
three (3) weeks after such commencement or within a reasonable period of time
after discovery if such items could not reasonably have been discovered within
such three (3) week period, but no later than one (1) year from the Term
Commencement Date. If Tenant shall not have commenced to occupy the Premises for
the Permitted Uses within thirty (30) days after the Term Commencement Date, a
certificate of completion by a licensed architect or registered engineer shall
be conclusive evidence that Landlord has performed all such obligations except
for items stated in such certificate to be incomplete or not in conformity with
such requirements. Tenant acknowledges that the Building will be undergoing
substantial renovation during the Term of the Lease. Tenant acknowledges that
its quiet enjoyment and access to the Premises during the Term may be disturbed
by the noise, dust, vibrations and other effects of demolition in the Building,
provided, however, that the same shall not unreasonably interfere with Tenant's
use and enjoyment of the Premises and Landlord shall use reasonable efforts to
avoid undue interference with Tenant's use of the Premises.

3.5 ALTERATIONS AND ADDITIONS.

     This Section 3.5 shall apply before and during the Term. Tenant shall not
make any alterations and additions to the Premises except in accordance with
plans and specifications first approved by Landlord which approval shall not be
unreasonably withheld, conditioned or delayed with respect to alterations which
satisfy the Alteration Conditions (as defined below). At the time Landlord
reviews the plans and specifications, Landlord shall give Tenant written notice
specifying which alterations and additions set forth in the plans and
specifications must be removed at Tenant's expense on or before the end of the
Term. In no event shall any alterations or additions be considered or approved
by Landlord which (a) involve or might affect any structural or exterior element
of the Building or building mechanical systems, including the common facilities
of the Building, or (b) will require unusual


                                       12



expense to readapt the Premises to normal office use on Lease termination or
increase the cost of construction or of insurance or taxes on the Building or
the Lot (together, the "Alteration Conditions"). All alterations and additions
shall become a part of the Premises, unless required or permitted to be removed
by Tenant hereunder. All of Tenant's alterations and additions and installation
and delivery of telephone systems, furnishings, and equipment shall be
coordinated with any work being performed by Landlord and shall be performed in
such manner, and by such persons as shall maintain harmonious labor relations
and not cause any damage to the Building or interference with Building
construction or operation and, except for installation of furnishings, equipment
and telephone systems, and except as otherwise expressly set forth herein, shall
be performed by general contractors first approved by Landlord. Before
commencing any work Tenant shall: secure all licenses and permits necessary
therefor; deliver to Landlord a statement of the names of all its contractors
and subcontractors (the identity of which must have been previously approved by
Landlord as hereinabove contemplated) and the estimated cost of all labor and
material to be furnished by them; and cause each contractor to carry (i)
worker's compensation insurance in statutory amounts covering all the
contractor's and subcontractor's employees and (ii) comprehensive public
liability insurance with such limits as Landlord may reasonably require, but in
no event less than a combined single limit of $1,500,000 (all such insurance to
be written in companies approved by Landlord and insuring Landlord and Tenant as
well as the contractors), and to deliver to Landlord certificates of all such
insurance. Tenant agrees to pay promptly when due, and to defend and indemnify
Landlord from and against, the entire cost of any work done on the Premises by
Tenant, its agents, employees or independent contractors, and not to cause or
permit any liens for labor or materials performed or furnished in connection
therewith to attach to the Building or the Lot and immediately to discharge any
such liens which may so attach. Tenant shall pay within fourteen (14) days after
being billed therefor by Landlord, as additional rent, one hundred percent
(100%) of any increase in real estate taxes on the Premises not otherwise billed
to Tenant which shall, at any time after the commencement of the Term, result
from any alteration, addition or improvement to the Premises made by or on
behalf of Tenant.

     In connection with the installation of telecommunication equipment by
Tenant, such installation shall occur only in such locations and in such a
manner as approved in writing by the Landlord and none of such wires, ducts or
equipment shall be located in areas outside the Premises (provided, however,
that Tenant may install wires and cables in risers and ducts outside the
Premises which are in existence on the date of this Lease and for which there
exists, in Landlord's sole discretion, adequate space for Tenant's wires and
cables). Telephone switches, antennae, electronic distribution boxes and similar
equipment shall only be located within the Premises. Landlord shall not be
liable for any loss, damage or interruption of service related to such
facilities.


                                       13



3.6 REPRESENTATIVES.

     Each party authorizes the other to rely in connection with their respective
rights and obligations under this Article III upon approval and other actions on
the party's behalf by Landlord's Representative in the case of Landlord or
Tenant's Representative in the case of Tenant or by any person designated in
substitution or addition by notice to the other party.


                                   ARTICLE IV
                                      RENT

4.1 ANNUAL RENT.

     Tenant agrees to pay rent to Landlord without any offset or reduction
whatever (except as made in accordance with the express provisions of this
Lease), the Annual Rent in equal monthly installments in advance on the first
day of each calendar month included in the Term after the Term Commencement
Date; and for any portion of a calendar month at the beginning or end of the
Term, at the proportionate rate payable for such portion, in advance.
Notwithstanding the foregoing, provided that there is no default by Tenant
hereunder which continues after the giving of any required notice and the
expiration of any applicable grace period, from and after the Term Commencement
Date until the Rent Commencement Date for the Third Floor Premises, Tenant shall
be required to pay Annual Rent with respect to the Second Floor Premises only in
the amount of $19,862.50 per calendar month and shall not be required to pay any
Annual Rent with respect to the Third Floor Premises until the Rent Commencement
Date for the Third Floor Premises, at which time the full amount of Annual Rent
set forth in Section 1.1 hereof shall thereafter be payable from Tenant to
Landlord.

4.2 ANNUAL OPERATING COST ESCALATION.

     In addition to Annual Rent, Tenant shall pay to Landlord as additional
rent, Tenant's Proportionate Share of Annual Operating Costs (as hereinafter
defined) which is in excess of $9.00 per rentable square foot. Tenant's
proportionate share of Annual Operating Costs shall be determined by multiplying
Annual Operating Costs by a fraction, the numerator of which is the Rentable
Floor Area of Tenant's Space and the denominator of which is the Total Rentable
Floor Area of the Building. In the event that the Building is not fully
occupied, such Annual Operating Costs which vary with occupancy shall be
adjusted to reflect the costs which would be incurred if the Building were 95%
occupied.

     Annual Operating Costs shall mean the actual expenses paid or incurred by
Landlord in the operation, maintenance and management of the Building and Lot
and all real estate taxes and assessments, general or special, ordinary or
extraordinary,


                                       14



foreseen or unforeseen, imposed upon the Building and Lot and any future
improvement of whatever kind thereto or thereon. Annual Operating Costs shall
include without limitation:

     (a) real estate taxes on the Building and Lot and off-site parking areas;
(b) installments and interest on assessments for public betterment or public
improvements; (c) expenses of any proceedings for abatement of taxes and
assessments with respect to any fiscal year or fraction of a fiscal year; (d)
service, repair, replacement and other maintenance to the Building and Lot and
components thereof; (e) wages and salaries (and taxes and other charges imposed
upon employers with respect to such wages and salaries) and fringe benefits and
worker's compensation insurance premiums paid to persons employed by the
Landlord for rendering service in the operation, maintenance, and repair of the
Building and Lot and related facilities and off-site parking areas and
amenities; (f) cost of independent contractors hired for the operation,
maintenance and repair of the Building and Lot and related facilities and
amenities (which payments may be to affiliates of Landlord provided the same are
at reasonable rates consistent with the type of occupancy and the services
rendered); (g) costs of electricity, steam, water, fuel, heating, lighting, air
conditioning, sewer, and other utilities chargeable to the operation and
maintenance of the Building and Lot net of tenant's electric; (h) cost of
insurance including insurance deductible for and relating to the Building and
the Lot, including fire and extended coverage (or such greater coverages as
Landlord may elect to carry), elevator, boiler, sprinkler leakage, water damage,
public liability and property damage, plate glass, and rent protection; (i)
costs of supplies; (j) costs of window cleaning, janitorial services, security
services, landscaping, snow and ice removal and painting; (k) sales or use taxes
on supplies and services; (1) consulting, accounting fees, legal, tax appeal,
engineering and other professional fees and expenses; (m) management fees
(provided that the percentage of gross revenue upon which such management fees
are based as of the date hereof shall not be changed); (n) contributions, costs
or expenses related to common areas or facilities and off-site parking areas of
any office park or development of which the Building or Lot are a part, (o)
alterations and improvements to the Building and Lot which are not capital in
nature made by reason of any requirement of any insurance underwriters or any
federal, state, or local statutes, regulations, ordinances, or any other duly
constituted public authorities having jurisdiction over the Building and Lot;
and (p) all Expense of Operation of the Food Services as defined in section
5.1.5 and (q) without limiting any of the foregoing, any other expense or charge
which, in accordance with sound accounting and management principles generally
accepted, would be construed as an operating expense. The term Operating Costs
shall not include the interest and amortization on mortgages for the Building
and Lot or leasehold interests therein; any charge for depreciation; leasing
commissions or legal fees for the negotiation and enforcement of leases; and the
cost of special services rendered to tenants (including Tenant) for which a
special charge is made.


                                       15



Annual Operating Costs shall exclude:

(1)  The cost of capital improvements, repairs or replacements to the Building
     except for Essential Capital Improvements;

(2)  Payments for rented equipment, the cost of which equipment would constitute
     a capital expenditure not includable in Annual Operating Expenses if such
     equipment were purchased;

(3)  The cost of correcting defects in the initial construction of the Building;

(4)  Insurance premiums attributable to any unusual tenant activity or
     improvements;

(5)  Federal, state or local income, franchise or estate taxes, and interest and
     penalties assessed by reason of Landlord's failure to pay real estate taxes
     when due;

(6)  Any items to the extent such items are reimbursed to Landlord by any third
     parties;

(7)  Salaries of officers and executives of Landlord not connected with the
     operation of the Building;

(8)  All costs related to the preparation of any portion of the Building for
     occupancy by a tenant or other occupant;

(9)  Any cost incurred by the negligent acts or omissions of Landlord, its
     agents and employees;

(10) Advertising and promotional expenses associated with the marketing of
     vacant space in the Building;

(11) Costs and expenses incurred by Landlord in connection with the repair of
     damage to the Building or Property caused by fire or other casualty,
     insured against to the extent of the applicable insurance proceeds;

(12) The cost of any item for which Landlord is reimbursed through condemnation
     awards; and

(13) Costs incurred due to violation by Landlord of any lease or any laws,
     rules, regulations or ordinances applicable to the Building.


                                       16



     In the event Landlord shall make a capital expenditure for Essential
Capital Improvements, as hereinafter defined, during any year, the annual
amortization of such expenditure (determined by dividing the amount of the
expenditure by the useful life of the improvement, as determined by Landlord and
consistent with generally accepted accounting principles), together with
interest at the greater of the Prime Rate prevailing plus 2% or Landlord's
actual borrowing rate for such Essential Capital Improvements shall be deemed
part of Annual Operating Costs for each year of such useful life. As used
herein, "Essential Capital Improvement" means any of the following:

     (i) a labor saving device, energy saving device or other installation,
improvement or replacement which reduces Operating Costs as referred to above,
whether or not voluntary or required by governmental mandate; or

     (ii) an installation, change, improvement, addition, alteration, or removal
of any architectural barriers, whether or not the foregoing are structural in
nature, made by reason of any governmental requirement whether or not such
governmental requirement exists on the date of the execution of this Lease if
such governmental requirement is or will be applicable generally to similar
office buildings; or

     (iii) an installation or improvement which directly enhances the health or
safety of tenants in the Building generally, whether or not voluntary or
required by governmental mandate (as for example, without limitation, for life
safety or security).

     (iv) costs or expenditures incurred in replacing compressors and
refrigeration equipment in order to comply with regulations regarding ozone
depleting refrigerants or resulting from the excessive cost of or inability to
obtain such materials.

4.3 ESTIMATED ANNUAL OPERATING EXPENSE ESCALATION PAYMENT.

     If, with respect to any fiscal year or fraction thereof during the Term,
Landlord estimates that Tenant will be obligated to pay Annual Operating Costs,
then Tenant shall pay, as additional rent, on the first day of each month of
such fiscal year and each ensuing fiscal year thereafter, an estimate equal to
1/12th of the estimated Annual Operating Cost Escalation for the respective
fiscal year ("Estimated Monthly Operating Expense Cost Payments"), with an
appropriate additional payment or refund to be made within 30 days after
Landlord's Statement (as hereafter defined) is delivered to Tenant. Landlord may
adjust such Estimated Monthly Annual Operating Cost Payment from time to time
and at any time during a fiscal year, and Tenant shall pay, as additional rent,
on the first day of each month following receipt of Landlord's notice thereof,
the adjusted Monthly Annual Operating Cost Payment.


                                       17



     As soon as practicable after the end of each fiscal year ending during the
Term and after lease termination, Landlord shall render a statement ("Landlord's
Statement") in reasonable detail and according to usual accounting practices
certified by Landlord and showing for the preceding fiscal year or fraction
thereof, as the case may be, Landlord's Annual Operating Costs, and Tenant's
Proportionate Share thereof, as defined above. Tenant shall have the right to
cause Landlord's determination of Tenant's Proportionate Share of Operating
Expenses to be audited by an auditor reasonably acceptable to Landlord. If such
audit shall indicate that Landlord's determination of the foregoing is (i)
overstated, or (ii) understated, then, in the case of (i) the difference shall
be credited to Tenant's next payment of Tenant's Proportionate Share of
Operating Expenses or, after the end of the Term, Landlord shall refund the
difference to Tenant within thirty (30) days after such determination, or in the
case of (ii) Tenant shall pay to Landlord the amount of such excess within 30
days after such determination. The cost of such audit shall be paid for by
Tenant unless such audit shall indicate an overstatement of more than five
percent (5%) in which case the cost of such audit shall be paid for by Landlord.
The obligations under this Paragraph shall survive the expiration of the Term or
earlier termination of this Lease.

4.4 ELECTRICITY.

     Tenant will be billed for electricity for Tenant's lights and outlet
consumption on a monthly basis based on an annual estimate of $1.00 per rentable
square foot. Should the actual average expense to Landlord per square foot for
Tenant's electricity be different, an additional charge or a credit will be made
at the end of each year's occupancy to be paid with or credited against the next
monthly charge for Tenant's electricity. Notwithstanding the foregoing, Landlord
reserves the right to assess Tenant's charge for electricity based on an
engineer's survey of Tenant's electrical usage conducted from time to time or on
the sub-metering of all or part of the Premises. Such charges for Tenant's
electricity shall be paid by Tenant as additional rent at the same time and in
the same manner as payments of Annual Rent. In addition, Tenant reserves the
right to install, at its own cost and expense, a check meter to verify Tenant's
consumption of electricity, in which case Tenant shall be billed for electricity
based on the actual readings of said meter.

     Tenant covenants and agrees that its use of electric current shall not
exceed 4.0 watts per square foot of usable floor area and that its total
connected lighting load will not exceed the maximum load from time to time
permitted by applicable governmental regulations. In the event Tenant introduces
into the Premises personnel or equipment which overloads the capacity of the
Building's electrical system or in any other way interferes with the system's
ability to perform properly, supplementary systems including check meters may,
if and as needed, at Landlord's option, be provided by Landlord, at Tenant's
expense. Landlord shall not in any way be liable or responsible to Tenant for
any loss or damage or expense which Tenant


                                       18



may sustain or incur if, during the Term of this Lease, either the quantity or
character of electric current is changed or electric current is no longer
available or suitable for Tenant's requirements due to a factor or cause beyond
Landlord's control.

     Landlord reserves the exclusive right to provide electric and other utility
service to the Building. Tenant may request permission from Landlord (which
consent may be withheld in its sole discretion) to arrange electric and other
utility service exclusively serving the Premises. Should such permission be
granted, however, such service shall be installed only in such locations and in
such manner as shall be specifically approved by Landlord in its sole
discretion, Tenant shall be responsible for restoration of any damage caused by
such installation and Tenant shall be responsible for removal of such
installations at the termination of this Lease. Landlord may limit Tenant's
choice of electrical or other utility providers in order to avoid proliferation
of such services to the Building or for any other reason. In no event, however,
shall Landlord be responsible for any damages or inconvenience caused by
interruption in or poor quality of electricity or other utility services
provided to the Building or the Premises unless such damages are caused by the
negligence of Landlord, its agents or employees.

4.5 CHANGE OF FISCAL YEAR.

     Landlord shall have the right from time to time to change the periods of
accounting under Section 4.2 to any annual period other than a calendar year,
and upon any such change all items referred to in Section 4.2 shall be
appropriately apportioned. In all Landlord's Statements rendered under Section
4.2, amounts for periods partially within and partially without the accounting
periods shall be appropriately apportioned, and any items which are not
determinable at the time of a Landlord's Statement shall be included therein on
the basis of Landlord's estimate, and with respect thereto Landlord shall render
promptly after determination a supplemental Landlord's Statement, and
appropriate adjustment shall be made according thereto. All Landlord's
Statements shall be prepared on an accrual basis of accounting.

4.6 PAYMENTS.

     All payments of Annual Rent and additional rent shall be made to Managing
Agent, or to such other person as Landlord may from time to time designate. If
any installment of Annual Base Rent or additional rent or payments due on
account of leasehold improvements is paid more than 10 days after the due date
thereof, at Landlord's election, it shall bear interest at a rate equal to the
average prime commercial rate from time to time established by the three largest
national banks in Boston, Massachusetts plus 4% per annum from such due date,
which interest shall be immediately due and payable as further additional rent.


                                       19




                                    ARTICLE V
                              LANDLORD'S COVENANTS

5.1 LANDLORD'S COVENANTS DURING THE TERM.

     Landlord covenants during the Term:

     5.1.1 Building Services - To furnish during normal working hours heat,
air-conditioning ("HVAC") elevator service and hot and chilled water service and
after normal working hours on business days cleaning service as shown in Exhibit
D. HVAC shall be provided to maintain reasonably comfortable temperatures for
normal occupancy of the Premises in accordance with minimum ASHRAE standards and
requirements. "Normal working hours" shall mean the hours of 8:00 a.m. through
6:00 p.m. Monday through Friday and the hours of 8:00 a.m. through 1:00 p.m. on
Saturdays, and no hours on legal holidays and Sundays; provided, however, that
Tenant shall have access to the Building 24 hours a day, 365 days a year, by
means of a key or other access device to the main lobby of the Building to be
provided to Tenant by Landlord. Tenant shall pay when due all amounts and
charges for such services during hours other than normal working hours and shall
indemnify and hold harmless Landlord from and against any and all claims,
liabilities, damages, losses, costs and expenses (including reasonable
attorneys' fees) in connection therewith. Landlord is not and shall not be
required to furnish to Tenant or any other occupant of the Premises telephone or
other communication service.

     5.1.2 Additional Building Services - To furnish, through Landlord's
employees or independent contractors, reasonable additional Building operation
services upon reasonable advance request of Tenant at equitable rates including
an administrative fee from time to time established by Landlord to be paid by
Tenant;

     5.1.3 Repairs - Except as otherwise provided in Article VII, to make such
repairs to the roof, exterior walls, floor slabs, other structural components,
base Building systems, and common facilities of the Building as may be necessary
to keep them in serviceable condition; and

     5.1.4 Tenant Directory - To include Tenant's name on the Tenant directory
maintained by Landlord in the main lobby of the Building and on the floor of the
Building on which the Premises are located, and to provide a Building standard
sign on or adjacent to the entrance door to the Premises.

     5.1.5 Food Service - Landlord (or any affiliate or agent designated by
Landlord) may provide, within the Building or any building in the office park in
which the Building is located known as CambridgePark (an "Office Park
Building"), a food service of a size, type, location and serving capacity as
Landlord shall deem suitable, in its sole discretion. All losses incurred by
Landlord in operating the food


                                       20



service facility during any fiscal year and properly allocable to the Building
and other Office Park Buildings (the "Food Service Losses") shall be added to
the Landlord's Annual Operating Costs for the Building and other Office Park
Buildings for the year in which such losses were incurred for the purpose of
calculating the Annual Operating Costs Escalation pursuant to Section 4.2. All
profits realized by the Landlord in operating the food service facility during
any fiscal year and properly allocable to the Building and other Office Park
Buildings (the "Food Service Profits") shall be credited against the Landlord's
Annual Operating Costs for the Building and other Office Park Buildings for such
year. For the purposes of this Section 5.1.5, the Food Service Profits of Losses
for any year shall be calculated by deducting from the Gross Receipts of the
Food Service (as hereinafter defined) all Expenses of Operation (as hereinafter
defined). Gross Receipts of the Food Service as used herein are defined to mean
the total amount in dollars of the actual prices charged, in cash, for food and
beverages served at the facility, excluding sums collected for any sales tax or
excise tax. The Expenses of Operation of the food service shall mean all
expenses of operating the food service facility, including without limitation,
salaries, wages, employment taxes and fringe benefits, food service
administration costs, food costs, concessionaire's costs, operating costs,
equipment maintenance and repair costs, if any, plus an annual return to the
Landlord upon its investment in establishing the food service facility
(including without limitation the cost of furniture, equipment, furnishings, and
related mechanical systems) equal to fifteen percent (15%) of its investment or
$50,000, whichever is less; provided, however, the Expenses of Operation shall
exclude any amounts otherwise included in Landlord's Annual Operating Costs.

     If during any six-month period, the mathematical average of the number of
luncheon meals served by the food service facility per day is fewer than 300, or
the Food Service Losses incurred by the Landlord in operating the food service
facility during such six-month period exceed $25,000, then the Landlord shall
have the right and option, in its sole discretion, to take any steps necessary
to reduce or eliminate the losses (including without limitation, modification or
termination of the food service), unless one hundred percent (100%) of the
tenants occupying the Building agree that the Landlord's Annual Operating Costs
hereunder for the purpose of calculating the Annual Operating Expense Escalation
shall include one hundred percent (100%) of the Food Service Losses, without
limitation.

     Landlord reserves the right to approve Tenant's use of a food service
operator other than the Landlord's food service operator, if any. Such approval
will not be unreasonably withheld.

     5.1.6 Quiet Enjoyment - That Landlord has the right to make this Lease and
that Tenant on paying the rent and performing its obligations hereunder shall
peacefully and quietly have, hold and enjoy the Premises throughout the Term


                                       21



without any manner of hindrance or molestation from Landlord or anyone claiming
under Landlord, subject however to all the terms and provisions hereof.

     5.1.7 Tenant's Costs - Landlord shall reimburse Tenant promptly for all
costs, including, without implied limitation, reasonable counsel fees, incurred
by Tenant in connection with the successful enforcement by Tenant of any
obligations of Landlord under this Lease.

5.2 INTERRUPTIONS.

     Landlord shall not be liable to Tenant for any compensation or reduction of
rent by reason of inconvenience or annoyance, injury, death or for loss of
business arising from power or other utility losses or shortages, air pollution
or contamination, or from the necessity of Landlord's entering the Premises for
any of the purposes in this Lease authorized, or for repairing the Premises or
any portion of the Building or the Lot or for any interruption or termination
(by reason of any cause reasonably beyond Landlord's control, including without
limitation, loss of any applicable license or government approval) of the food
service provided by Landlord pursuant to Section 5.1.5. In case Landlord is
prevented or delayed from making any repairs, alterations or improvements, or
furnishing any service or performing any other covenant or duty to be performed
on Landlord's part, by reason of any cause beyond Landlord's reasonable control,
Landlord shall not be liable to Tenant therefor, nor, except as expressly
otherwise provided in Article VII, shall Tenant be entitled to any abatement or
reduction of rent by reason thereof, nor shall the same give rise to a claim in
Tenant's favor that such failure constitutes actual or constructive total or
partial, eviction from the Premises.

     Landlord reserves the right to stop any service or utility system when
necessary by reason of accident or emergency or until necessary repairs have
been completed. Except in case of emergency repairs, Landlord will give Tenant
reasonable advance notice of any contemplated stoppage and will use reasonable
efforts to avoid unnecessary inconvenience to Tenant by reason thereof.

     Landlord also reserves the right to institute such policies, programs and
measures as may be necessary, required or expedient for the conservation or
preservation of energy or energy services or as may be necessary or required to
comply with applicable codes, rules, regulations or standards.


                                       22




                                   ARTICLE VI
                               TENANT'S COVENANTS

6.1 TENANT'S COVENANTS DURING THE TERM.

     Tenant covenants during the Term and such further time as Tenant occupies
any part of the Premises:

     6.1.1 Tenant's Payments - To pay when due (a) all Annual Rent, (b) all
taxes which may be imposed on Tenant's personal property in the Premises
(including, without limitation, Tenant's fixtures and equipment) regardless to
whomever assessed, (c) as additional rent, Tenant's proportionate share of
Annual Operating Costs, (d) all charges by public utilities for electricity,
telephone (including service inspections therefor) and other services rendered
to the Premises not otherwise required hereunder to be furnished by Landlord
without charge and not consumed in connection with any services required to be
furnished by Landlord without charge, (e) as additional rent, all costs for
Landlord's Work attributable to change orders and any work performed in the
Premises by Landlord or Tenant in excess of Landlord's Work, and (f) as
additional rent, all charges to Landlord for services rendered pursuant to
Section 5.1.2 hereof.

     6.1.2 Repairs and Yielding Up - Except as otherwise provided in Article VII
and Section 5.1.3, to keep the Premises in good order, repair and condition,
reasonable wear only excepted; and at the expiration or termination of this
Lease peaceably to yield up the Premises and all alterations and additions
therein, including all telephone and data wiring installed by or at the request
of Tenant, in such order, repair and condition, first removing all goods and
effects of Tenant and any alterations and additions, the removal of which is
required by agreement or specified to be removed by Landlord pursuant to Section
3.5 and repairing all damage caused by such removal and restoring the Premises
and leaving them clean and neat.

     6.1.3 Occupancy and Use - Continuously from the Commencement Date, to use
and occupy the Premises only for the Permitted Uses; not to injure or deface the
Building or the Lot; to keep the Premises clean and in a neat and orderly
condition; and not to permit in the Premises any use thereof which is improper,
offensive, contrary to law or ordinances, or liable to create a nuisance or to
create an unsafe or hazardous condition, or to invalidate or increase the
premiums for any insurance on the Building or its contents or liable to render
necessary any alteration or addition to the Building; not to dump, flush, or in
any way introduce any Hazardous Materials or any other toxic substances into the
septic, sewage or other waste disposal system serving the Premises, not to
generate, store or dispose of Hazardous Materials in or on the Premises (except
for reasonable quantities of office supplies which Tenant


                                       23



shall use, store and dispose of in compliance with applicable law), or the Lot
or dispose of Hazardous Materials from the Premises to any other location
without the prior written consent of Landlord and then only in compliance with
the Resource Conservation and Recovery Act of 1976, as amended, 42 U.S.C. ss.
6901 et seq., and all other applicable laws, ordinances and regulations; to
notify Landlord of any incident which would require the filing of a notice under
applicable federal, state, or local law; not to use, store or dispose of
Hazardous Materials on the Premises (except for reasonable quantities of office
supplies which Tenant shall use, store and dispose of in compliance with
applicable law), without first submitting to Landlord a list of all such
Hazardous substances and all permits required therefor and thereafter providing
to Landlord on an annual basis Tenant's certification that all such permits have
been renewed with copies of such renewed permits; and to comply with the orders
and regulations of all governmental authorities with respect to zoning,
building, fire, health and other codes, regulations, ordinances or laws
applicable to the Premises. Notwithstanding anything in this Lease to the
contrary, Landlord, and not Tenant, shall be responsible for making all
improvements or alterations to the Building which are required to cause the same
to comply with all present and future governmental laws unless the same shall be
required (a) by virtue of Tenant's specific use of the Premises or (b) in the
Premises in connection with the improvement of the Premises by Tenant, including
Tenant's Work. As used herein, "Hazardous Materials" shall mean and include, but
shall not be limited to, any petroleum product and all hazardous or toxic
substances or wastes including any asbestos-containing materials, waste oils,
solvents and chlorinated oils, polychlorinated biphenyls (PCBs), or substances
which are included under or regulated by any federal, state or local law, rule
or regulation (whether now existing or hereafter enacted or promulgated, as they
may be amended from time to time) pertaining to the environment, contamination
or clean-up (all such laws, rules and regulations being referred to collectively
as the "Environmental Laws"), including, without limitation, the Comprehensive
Environmental Response Compensation and Liability Act of 1980, as amended, 42
U.S.C. ss. 9601 and regulations adopted pursuant to said Act.

     6.1.4 Rules and Regulations - To comply with the Rules and Regulations set
forth in Exhibit E and all other reasonable Rules and Regulations of uniform
application hereafter made by Landlord, of which Tenant has been given notice,
for the care and use of the Building and the Lot and their facilities and
approaches, it being understood that Landlord shall not be liable to Tenant for
the failure of other tenants of the Building to conform to such Rules and
Regulations.

     6.1.5 Safety Appliances - To keep the Premises equipped with all safety
appliances required by law or ordinance or any other regulation of any public
authority because of any use made by Tenant and to procure all licenses and
permits so required because of such use and, if requested by Landlord, to do any
work so required because of such use, it being understood that the foregoing
provisions shall not be construed to broaden in any way Tenant's Permitted Uses.


                                       24



     6.1.6 Assignment and Subletting.

     Not without the prior written consent of Landlord to assign, mortgage,
pledge, encumber, sell or transfer this Lease, in whole or in part, to make any
sublease, or to permit occupancy of the Premises or any part thereof by anyone
other than Tenant, voluntarily or by operation of law (it being understood that
in no event shall Landlord consent to any such assignment, sublease or occupancy
if the same is at a rent that is less than eighty percent (80%) of the then
applicable fair market rental rate for space in the Building); and as additional
rent, to reimburse Landlord promptly for reasonable legal and other expenses
incurred by Landlord in connection with any request by Tenant for consent to
assignment or subletting; no assignment or subletting shall affect the
continuing primary liability of Tenant (which, following assignment, shall be
joint and several with the assignee); no consent to any of the foregoing in a
specific instance shall operate as a waiver in any subsequent instance.
Notwithstanding the foregoing, Landlord's consent shall not be required for any
assignment or sublease to an entity controlling, controlled by, or in common
control with Tenant, nor to any entity that succeeds to Tenant's interest in
this Lease by reason of merger, acquisition, consolidation or reorganization;
provided, however, such successor entity shall have a net worth equal to or
greater than the net worth of Tenant as of the execution date of this Lease.
Landlord's consent to any proposed assignment or subletting is required both as
to the terms and conditions thereof, and as to the creditworthiness of the
proposed assignee or subtenant and the consistency of the proposed assignee's or
subtenant's business with other uses and tenants in the Building. In the event
that any assignee or subtenant pays to Tenant any amounts in excess of the
Annual Rent and additional rent then payable hereunder, or pro rata portion
thereof on a square footage basis for any portion of the Premises, Tenant shall
promptly pay 100% of said excess (less Tenant's costs and expenses in connection
with such assignment or sublease) to Landlord as and when received by Tenant. If
Tenant requests Landlord's consent to assign this Lease or sublet more than
forty percent (40%) of the Premises, Landlord shall have the option, exercisable
by written notice to Tenant given within 10 days after receipt of such request,
to terminate this Lease as of a date specified in such notice which shall be not
less than 30 or more than 60 days after the date of such notice, provided,
however, in the case of a proposed sublease, such termination shall apply only
to so much of the Premises as is intended to be sublet and, if six (6) months or
more of the Term of this Lease will remain after expiration of the term of such
sublease, only for the term of such sublease. Landlord may, in its sole
discretion, withhold consent to any proposed assignment or subletting to another
tenant of the Building or an affiliate of such tenant or an entity (or affiliate
of any entity) with which Landlord was negotiating for space in the Building
during the preceding eighteen (18) months.

     Landlord agrees not to unreasonably withhold or delay its consent to an
assignment of this Lease or a sublease of a portion of the Premises by Tenant


                                       25




provided that (a) no event of default by Tenant exists hereunder, and no
condition exists which with the giving of notice or the passage of time, or
both, would constitute an event of default hereunder unless the same is cured
within the applicable cure period, and (b) Landlord determines that the proposed
assignee or sublessee (i) is a first-class office establishment and would use
the leased premises solely for the Permitted Uses, and (ii) has a financial
standing reasonably acceptable to Landlord, giving due regard to the amount of
space involved, as evidenced by financial statements in scope and substance
reasonably satisfactory to Landlord and in conformity with generally accepted
accounting principles and, if requested by Landlord, certified by a certified
public accountant acceptable to Landlord.

     6.1.7 Indemnity - To defend, with counsel approved by Landlord, all actions
against Landlord, Managing Agent, any partner, member, trustee, stockholder,
officer, director, employee or beneficiary of Landlord or Managing Agent,
holders of mortgages secured by the Premises or the Building and Lot and any
other party having an interest in the Premises ("Indemnified Parties") with
respect to, and to pay, protect, indemnify and save harmless, to the extent
permitted by law, all Indemnified Parties from and against, any and all
liabilities, losses damages, costs, expenses (including reasonable attorneys'
fees and expenses), causes of action, suits, claims, demands or judgments of any
nature arising from or related to (i) injury to or death of any person, or
damage to or loss of property, on the Premises or on adjoining sidewalks,
streets or ways in connection with Tenant's occupancy of the Premises or
connected with the use, condition or occupancy of any of the foregoing unless
caused by the negligence of Landlord or its servants or agents, (ii) violation
of this Lease by Tenant, or (iii) any act, fault, omission, or other misconduct
of Tenant or its agents, employees, contractors, licensees, sublessees or
invitees or (iv) the use, generation, storage or disposal of Hazardous Materials
by Tenant or its agents, employees or invitees on the Premises, the Building or
Lot or any portion thereof or any surrounding area, including, without
limitation, any and all liabilities, losses, damages, costs, expenses (including
reasonable attorneys' fees and expenses), causes of action, suits, claims,
demands or judgments of any nature arising from or related to removal or other
remediation of any Hazardous Materials or precautions required to protect
against the release of Hazardous Materials by Tenant or its agents, employees,
contractors, licensees, sublessees or invitees into the environment to the
extent required by any Environmental Laws.

     6.1.8 Tenant's Insurance - To maintain (a) all risk property insurance in
amounts sufficient to fully cover Tenant's improvements and all property in the
Premises which is not owned by Landlord and (b) commercial general liability
insurance on the Premises, with Landlord named as an additional insured,
indemnifying Landlord and Tenant against all claims and demands for (i) injury
to or death of any person or damage to or loss of property, on the Premises or
adjoining walks, streets or ways in connection with Tenant's occupancy of the
Premises, or connected with the use, condition or occupancy of any of the
foregoing unless caused


                                       26



by the negligence of Landlord or its servants or agents, (ii) violation of this
Lease by Tenant, or (iii) any act, fault or omission, or other misconduct of
Tenant or its agents, employees, contractors, licensees, sublessees or invitees,
in amounts which shall, at the beginning of the Term, be at least equal to the
limits set forth in Section 1.1, and from time to time during the Term, shall be
for such higher limits, if any, as are customarily carried in the area in which
the Premises are located on property similar to the Premises and used for
similar purposes, and shall be written on the "Occurrence Basis," and to furnish
Landlord with certificates thereof. Such insurance shall be effected under valid
and enforceable policies with insurers authorized to do business in
Massachusetts as stock or mutual companies that are rated in the current edition
of Best's Key Rating Guide Property and Casualty as A and as Class VII or
higher. Such policies shall name Landlord and Tenant as the insureds as their
respective interests may appear. Not later than the first to occur of (a) the
Commencement Date or (b) the commencement of any activities by Tenant in or
about the Premises and thereafter not less than 30 days prior to the expiration
dates of the expiring policies theretofore furnished pursuant to this Section
6.1.8, Tenant shall deliver to Landlord certificates of insurance issued by the
insurers evidencing all such policies in form satisfactory to Landlord,
accompanied by evidence satisfactory to Landlord of payment of the first
installment of the premiums. Each such policy shall provide that it may not be
canceled and that its form, terms or conditions may not be changed without at
least 30 days' prior written notice to each insured named therein.

     6.1.9 Tenant's Worker's Compensation Insurance - To keep all of Tenant's
employees working in the Premises covered by worker's compensation insurance in
statutory amounts and to furnish Landlord with certificates thereof.

     6.1.10 Landlord's Right of Entry - To permit Landlord and Landlord's agents
entry: to examine the Premises at reasonable times upon reasonable prior notice
(except in the event of an emergency) and, if Landlord shall so elect, to make
repairs or replacements; to remove, at Tenant's expense, any changes, additions,
signs, curtains, blinds, shades, awnings, aerials, or the like not consented to
in writing; and to show the Premises to prospective tenants during the nine (9)
months preceding expiration of the Term and to prospective purchasers and
mortgagees at all reasonable times upon reasonable prior notice.

     6.1.11 Loading - Not to place Tenant's Property, as defined in Section
6.1.13, upon the Premises so as to exceed a rate of 50 pounds of live load per
square foot and not to move any safe, vault or other heavy equipment in, about
or out of the Premises except in such manner and at such times as Landlord shall
in each instance approve; Tenant's business machines and mechanical equipment
which cause vibration or noise that may be transmitted to the Building structure
or to any other leased space in the Building shall be placed and maintained by
Tenant in settings of


                                       27



cork, rubber, spring, or other types of vibration eliminators sufficient to
eliminate such vibration or noise.

     6.1.12 Landlord's Costs - In case Landlord shall be made party to any
litigation commenced by or against Tenant or by or against any parties in
possession of the Premises or any part thereof claiming under Tenant, to pay, as
additional rent, all costs including, without implied limitation, reasonable
counsel fees incurred by or imposed upon Landlord in connection with such
litigation and, as additional rent, also to pay all such costs and fees incurred
by Landlord in connection with the successful enforcement by Landlord of any
obligations of Tenant under this Lease.

     6.1.13 Tenant's Property - All the furnishings, fixtures, equipment,
effects and property of every kind, nature and description of Tenant and of all
persons claiming by, through or under Tenant which, during the continuance of
this Lease or any occupancy of the Premises by Tenant or anyone claiming under
Tenant, may be on the Premises or elsewhere in the Building or on the Lot shall
be at the sole risk and hazard of Tenant, and if the whole or any part thereof
shall be destroyed or damaged by fire, water or otherwise, or by the leakage or
bursting of water pipes, steam pipes, or other pipes, by theft, or from any
other cause, no part of said loss or damage is to be charged to or to be borne
by Landlord unless due to the negligence of Landlord.

     6.1.14 Labor or Materialmen's Liens - To pay promptly when due the entire
cost of any work done on the Premises by Tenant, its agents, employees, or
independent contractors; not to cause or permit any liens for labor or materials
performed or furnished in connection therewith to attach to the Premises; and
immediately to discharge any such liens which may so attach.

     6.1.15 Changes or Additions - Not to make any changes or additions to the
Premises without Landlord's prior written consent and only in accordance with
Article III hereto, provided that Tenant shall reimburse Landlord for all costs
incurred by Landlord in reviewing Tenant's proposed changes or additions, and
provided further that, in order to protect the functional integrity of the
Building, all changes and additions shall be performed by contractors selected
from a list of approved contractors prepared by Landlord from time to time.

     6.1.16 Holdover - To pay to Landlord the greater of twice (a) the then fair
market rent as conclusively determined by Landlord or (b) the total of the
Annual Rent and all additional rent then applicable for each month or portion
thereof Tenant shall retain possession of the Premises or any part thereof after
the termination of this Lease, whether by lapse of time or otherwise, and also
to pay all damages sustained by Landlord on account thereof; the provisions of
this subsection shall not operate as a waiver by Landlord of the right of
reentry provided in this Lease. At the option of Landlord exercised by a written
notice given to Tenant while such holding over


                                       28



continues, such holding over shall constitute an extension of this Lease for a
period of one year.

     6.1.17 Security - To indemnify, and save Landlord harmless from any claim
for injury to person or damage to property asserted by any personnel, employee,
guest, invitee or agent of Tenant which is suffered or occurs in or about the
Premises by reason of the act of any intruder or any other person in or about
the Premises.

     6.1.18 Tenant Financial Statements - Tenant shall provide Landlord with
audited financial statements on an annual basis, within ninety (90) days of
Landlord's written request after the end of Tenant's fiscal year. Landlord
agrees to keep all such statements confidential and not to release them without
the prior consent of Tenant, except as otherwise required by law or compelled by
legal process.

                                   ARTICLE VII
                      DAMAGE AND DESTRUCTION; CONDEMNATION

7.1 FIRE OR OTHER CASUALTY.

     7.1.1 Subject to the provisions of Section 7.1.2 hereof, in the event
during the Term hereof the Premises shall be partially damaged (as distinguished
from "substantially damaged" as such term is hereinafter defined) by fire,
explosion, casualty or any other occurrence covered or as may be required to be
covered, as herein provided, by Landlord's insurance or by such casualty plus
required demolition, or by action taken to reduce the impact of any such event,
Landlord shall forthwith proceed to repair such damage and restore the Premises,
or so much thereof as was originally constructed or delivered by Landlord to
substantially its condition at the time of such fire, explosion, casualty or
occurrence, provided that Landlord shall not be obligated to expend for such
repair an amount in excess of the insurance proceeds recovered as a result of
such damage and, further provided that Tenant is not then in default of any of
its obligations under this Lease beyond any applicable cure period. Landlord
shall not be responsible for any delay which may result from any cause beyond
Landlord's reasonable control.

     7.1.2 If, however, (i) the Premises should be damaged or destroyed (a) by
fire or other casualty (1) to the extent of 25% or more of the cost of
replacement, or (2) so that 25% or more of the principal area contained in the
Premises shall be rendered untenantable, or (b) by any casualty other than those
covered by insurance policies required to be maintained by Landlord under this
Lease (hereinafter "substantially damaged"), or (ii) the Premises shall be
damaged in whole or in part during the last year of the Term, or (iii) there
shall be damage to the Premises of a character as cannot reasonably be expected
to be repaired within 12 months from the date of casualty, or (iv) such
restoration involves the demolition of or repair of damage to 25% percent or
more of the Premises, or (v) applicable law requires the demolition of


                                       29



the Building or forbids the rebuilding of the damaged portion of the Building,
or (vi) such restoration requires repairs in an amount in excess of the
insurance proceeds recovered or recoverable, or (vii) Landlord's mortgagee shall
require that the insurance proceeds from such damage or destruction be applied
against the principal balance due on any mortgage, Landlord may, at its option,
either terminate this Lease or elect to repair the Premises and Landlord shall
notify Tenant as to its election within 90 days after such fire or casualty. If
Landlord elects to terminate this Lease, the Term hereof shall end on the date
specified in the notice (which shall be the end of a calendar month and not
sooner than 30 days after such election was made). If Landlord does not elect to
terminate this Lease, then Landlord shall perform such repairs set forth in
Section 7.1.3 hereof and Tenant shall perform such repairs in the Building as
set forth in Section 7.1.4 hereof, and the Term shall continue without
interruption and this Lease shall remain in full force and effect.

     If Landlord has not elected to terminate this Lease and (a) if there shall
be damage to the Premises of a character as cannot (in the judgment of
Landlord's engineer) reasonably be expected to be repaired within 280 days from
the date of casualty, (b) such damage is not substantially repaired within 280
days after the date of casualty, or (c) such damage occurs during the last year
of the Term, then Tenant may, at its option, terminate this Lease provided that
Tenant's election shall be made by notice to Landlord which in the case of (a)
shall be within thirty (30) days of Landlord's delivery of the estimate of
Landlord's engineer as to the time period required for restoration, in the case
of (b) shall be made within 310 days after the date of casualty, provided that
such option to terminate shall be null and void and this Lease shall continue in
full force and effect if Landlord substantially completes such repairs within
thirty (30) days after Tenant's notice to Landlord, and in the case of (c) shall
be made within thirty (30) days after the date of casualty.

     7.1.3 If Landlord or Tenant do not elect to terminate this Lease as
provided in Section 7.1.2 hereof and if Tenant is not then in default of any of
its obligations under the Lease beyond any applicable cure period provided for
herein, Landlord shall, provided any third party mortgagee of the Building makes
insurance proceeds available for restoration, reconstruct as much of the
Premises as was originally constructed by Landlord (it being understood by
Tenant that Landlord shall not be responsible for any reconstruction of
leasehold improvements, which reconstruction is the sole responsibility of
Tenant) to substantially its condition at the time of such damage, but Landlord
shall not be responsible for any delays which may result from any cause beyond
Landlord's reasonable control.

     7.1.4 If Landlord or Tenant do not elect to terminate this Lease as
provided in Section 7.1.2 hereof; Tenant shall, at its own cost and expense,
repair and restore the Premises in accordance with the provisions of Section
6.1.15 hereof to the extent not required to be repaired by Landlord pursuant to
the provisions of this Section 7.1, including, but not limited to, the repairing
and/or replacement of its merchandise,


                                       30



trade fixtures, furnishings and equipment in a manner and to at least a
condition equal to that prior to its damage or destruction. Tenant agrees to
commence the performance of its work when notified by Landlord that the work to
be performed by Tenant can, in accordance with good construction practices, then
be commenced and Tenant shall complete such work as promptly thereafter as is
practicable.

     7.1.5 All proceeds payable from Landlord's insurance policies with respect
to the Premises shall belong to and shall be payable to Landlord. If Landlord
does not elect to terminate this Lease as provided in Section 7.1.2 hereof,
Landlord shall disburse and apply so much of any insurance recovery as shall be
necessary against the cost to Landlord of restoration and rebuilding of
Landlord's work referred to in Section 7.1.3 hereof, subject to the prior rights
of any lessor under a ground or underlying lease covering the Building and/or
the holder of any mortgage liens against the Building.

     7.1.6 In the event that the provisions of Section 7.1.1 or Section 7.1.2
shall become applicable, the Annual Rent and additional rent shall be abated or
reduced proportionately during any period in which, by reason of such damage or
destruction, there is substantial interference with the operation of the
business of Tenant in the Premises, having regard to the extent to which Tenant
may be required to discontinue its business in the Premises, and such abatement
or reduction shall continue for the period commencing with such destruction or
damage and ending with the earlier of (a) completion by Landlord of such work,
repair and/or reconstruction as Landlord is obligated to do and such additional
work, repair and/or reconstruction as is necessary to put the Premises in such
condition as Tenant requires to use the Premises for the Permitted Uses, or (b)
sixty (60) days after substantial completion by Landlord of such work, repair
and/or reconstruction as Landlord is obligated to do, provided that if Tenant
uses reasonable and diligent efforts to put the Premises in condition for
Tenant's use, such sixty (60) day period shall be extended for such period as
Tenant may reasonably require for such purpose not to exceed thirty (30) days.

7.2 EMINENT DOMAIN.

     If, after the execution and before termination of this Lease, the entire
Premises shall be taken by eminent domain or destroyed by the action of any
public or quasi-public authority, or in the event of conveyance in lieu thereof,
the Term shall cease as of the day possession shall be taken by such authority,
and Tenant shall pay rent up to that date with a pro-rata refund by Landlord of
such rent and additional rent as shall have been paid in advance for a period
subsequent to the date of the taking of possession.

     If less than 25% of the Premises shall be so taken or conveyed, this Lease
shall cease only with respect to the parts so taken or conveyed, as of the day
possession


                                       31



shall be taken, and Tenant shall pay rent up to that day, with an appropriate
refund by Landlord of such rent as may have been paid in advance for a period
subsequent to the date of the taking of possession, and thereafter the Annual
Rent shall be equitably adjusted. Pending agreement of such rental adjustment,
Tenant agrees to pay to Landlord the Annual Rent and additional rent in effect
immediately prior to the taking by eminent domain. Landlord shall at its expense
make all necessary repairs or alterations so as to constitute the remaining
premises a complete architectural unit.

     If more than 25% of the Premises shall be so taken or conveyed, then the
Term shall cease only as respects the part so taken or conveyed, from the day
possession shall be taken, and Tenant shall pay rent to that date with an
appropriate refund by Landlord of such rent as may have been paid in advance for
a period subsequent to the date of the taking of possession, but Landlord shall
have the right to terminate this Lease upon notice to Tenant in writing within
30 days after such taking of possession. If Landlord does not elect to terminate
the Lease, all of the terms herein provided shall continue in effect except that
the Annual Rent shall be equitably adjusted, and Landlord shall make all
necessary repairs or alterations so as to constitute the remaining premises a
complete architectural unit. Notwithstanding the foregoing, if any portion of
the Premises shall be taken or conveyed and the balance of the Premises is
rendered unsuitable for Tenant's business purposes in Tenant's reasonable
judgment, this Lease shall terminate as of the date of the taking of possession.

     All compensation awarded for any such taking or conveyance, whether for the
whole or a part of the Premises, shall be the property of Landlord, whether such
damages shall be awarded as compensation for diminution in the value of the
leasehold or of the fee of or underlying leasehold interest in the Premises, and
Tenant hereby assigns to Landlord all of Tenant's right, title and interest in
and to any and all such compensation; provided, however, that Tenant shall be
entitled to seek a separate award for Tenant's stock, trade fixtures and
relocation expense.

     In the event of any taking of the Premises or any part thereof for
temporary use, this Lease shall be and remain unaffected thereby and rent shall
not abate.

                                  ARTICLE VIII
                               RIGHTS OF MORTGAGEE

 8.1 PRIORITY OF LEASE.

     This Lease is and shall continue to be subject and subordinate to any
presently existing mortgage or deed of trust of record covering the Lot or
Building or both (the "mortgaged premises"). The holder of any such presently
existing mortgage or deed of trust shall have the election to subordinate the
same to the rights and interests of


                                       32



Tenant under this Lease exercisable by filing with the appropriate recording
office a notice of such election, whereupon the Tenant's rights and interests
hereunder shall have priority over such mortgage or deed of trust. Landlord
agrees to deliver to Tenant a non-disturbance agreement executed by the holder
of such mortgage or deed of trust and shall use reasonable and diligent efforts
to do so within thirty (30) days after full execution of the Lease and delivery
of the Security Deposit by Tenant to Landlord.

     Unless the option provided for in the next following sentence shall be
exercised, this Lease shall be superior to and shall not be subordinate to, any
mortgage, deed of trust or other voluntary lien hereafter placed on the
mortgaged premises. The holder of any such mortgage, deed of trust or other
voluntary lien shall have the option to subordinate this Lease to the same,
provided that such holder enters into an agreement with Tenant by the terms of
which the holder will agree to recognize the rights of Tenant under this Lease
and to accept Tenant as tenant of the Premises under the terms and conditions of
this Lease in the event of acquisition of title by such holder through
foreclosure proceedings or otherwise and Tenant will agree to recognize the
holder of such mortgage as Landlord in such event, which agreement shall be made
to expressly bind and inure to the benefit of the successors and assigns of
Tenant and of the holder and upon anyone purchasing the mortgaged premises at
any foreclosure sale. Any such mortgage to which this Lease shall be
subordinated may contain such terms, provisions and conditions as the holder
deems usual or customary.

8.2 RIGHTS OF MORTGAGE HOLDERS; LIMITATION OF MORTGAGEE'S LIABILITY.

     The word "mortgage" as used herein includes mortgages, deeds of trust or
other similar instruments evidencing other voluntary liens or encumbrances, and
modifications, consolidations, extensions, renewals, replacements and
substitutes thereof. The word "holder" shall mean a mortgagee, and any
subsequent holder or holders of a mortgage. Until the holder of a mortgage shall
enter and take possession of the Premises for the purpose of foreclosure, such
holder shall have only such rights of Landlord as are necessary to preserve the
integrity of this Lease as security. Upon entry and taking possession of the
Premises for the purpose of foreclosure, such holder shall have all the rights
of Landlord. Notwithstanding any other provision of this Lease to the contrary,
including without limitation Section 10.4, no such holder of a mortgage shall be
liable, either as mortgagee or as assignee, to perform, or be liable in damages
for failure to perform any of the obligations of Landlord unless and until such
holder shall enter and take possession of the Premises for the purpose of
foreclosure, and such holder shall not in any event be liable to perform or for
failure to perform the obligations of Landlord under Section 3.2. Upon entry for
the purpose of foreclosure, such holder shall be liable to perform all


                                       33



of the obligations of Landlord (except for the obligations under Section 3.2),
subject to and with the benefit of the provisions of Section 10.4, provided that
a discontinuance of any foreclosure proceeding shall be deemed a conveyance
under said provisions to the owner of the equity of the Premises.

8.3 MORTGAGEE'S ELECTION.

     Notwithstanding any other provision to the contrary contained in this
Lease, if prior to substantial completion of Landlord's obligations under
Article III, any holder of a first mortgage on the mortgaged premises enters and
takes possession thereof for the purpose of foreclosing the mortgage, such
holder may elect, by written notice given to Tenant and Landlord at any time
within ninety (90) days after such entry and taking of possession, not to
perform Landlord's obligations under Article III, and in such event such holder
and all persons claiming under it shall be relieved of all obligations to
perform, and all liability for failure to perform, said Landlord's obligations
under Article III, and Tenant may terminate this Lease and all its obligations
hereunder by written notice to Landlord and such holder given within thirty (30)
days after the day on which such holder shall have given its notice as
aforesaid.

8.4 NO PREPAYMENT OR MODIFICATION, ETC.

     Tenant shall not pay Annual Rent, additional rent, or any other charge more
than thirty (30) days prior to the due date thereof. No prepayment of Annual
Rent, additional rent or other charge, no assignment of this Lease and no
agreement to modify so as to reduce the rent, change the Term, or otherwise
materially change the rights of Landlord under this Lease, or to relieve Tenant
of any obligations or liability under this Lease, shall be valid unless
consented to in writing by Landlord's mortgagees of record, if any.

8.5 NO RELEASE OR TERMINATION.

     No act or failure to act on the part of Landlord which would entitle Tenant
under the terms of this Lease, or by law, to be relieved of Tenant's obligations
hereunder or to terminate this Lease, shall result in a release or termination
of such obligations or a termination of this Lease unless (i) Tenant shall have
first given written notice of Landlord's act or failure to act to Landlord's
mortgagees of record, if any, specifying the act or failure to act on the part
of Landlord which could or would give basis to Tenant's rights and (ii) such
mortgagees, after receipt of such notice, have failed or refused to correct or
cure the condition complained of within a reasonable time thereafter, but
nothing contained in this Section 8.5 shall be deemed to impose any obligation
on any such mortgagee to correct or cure any such condition. "Reasonable time"
as used above means and includes a reasonable time to obtain possession of the
mortgaged premises, if the mortgagee elects to do so, and a


                                       34



reasonable time to correct or cure the condition if such condition is determined
to exist.

8.6 CONTINUING OFFER.

     The covenants and agreements contained in this Lease with respect to the
rights, powers and benefits of a mortgagee (particularly, without limitation
thereby, the covenants and agreements contained in this Article VIII) constitute
a continuing offer to any person, corporation or other entity, which by
accepting or requiring an assignment of this Lease or by entry or foreclosure
assumes the obligations herein set forth with respect to such mortgagee; such
mortgagee is hereby constituted a party to this Lease as an obligee hereunder to
the same extent as though its name were written hereon as such; and such
mortgagee shall be entitled to enforce such provisions in its own name. Tenant
agrees on request of Landlord to execute and deliver from time to time any
agreement which may reasonably be deemed necessary to implement the provisions
of this Article VIII.

                                   ARTICLE IX
                                     DEFAULT

9.1 EVENTS OF DEFAULT.

     If any default by Tenant continues, in case of Annual Rent, additional rent
or any other monetary obligation to Landlord for more than five (5) days after
notice (provided that no notice shall be required if Landlord has defaulted in
any such obligation two (2) or more times in any twelve (12) month period), or
if Tenant fails to provide an estoppel certificate in accordance with Section
10.10 hereof, or if any default by Tenant continues in any other case for more
than thirty (30) days after notice and such additional time, if any, as is
reasonably necessary to cure the default if the default is of such a nature that
it cannot reasonably be cured in thirty (30) days and Tenant promptly commences
to cure such default and diligently pursues such cure without interruption to
completion; or if Tenant becomes insolvent, fails to pay its debts as they fall
due, files a petition under any chapter of the U.S. Bankruptcy Code, 11 U.S.C.
101 et seq., as it may be amended (or any similar petition under any insolvency
law of any jurisdiction); or if such petition is filed against Tenant (and the
same is not dismissed within sixty (60) days thereafter); or if Tenant proposes
any dissolution, liquidation, composition, financial reorganization or
recapitalization with creditors, makes an assignment or trust mortgage for
benefit of creditors; or if a receiver, trustee, custodian or similar agent is
appointed or takes possession with respect to any property of Tenant (and the
same is not released within sixty (60) days thereafter); or if the leasehold
hereby created is taken on execution or other process of law in any action
against Tenant; then, and in any such case, Landlord and the agents and servants
of Landlord may, in addition to and not in derogation of any


                                       35



remedies for any preceding breach of covenant, immediately or at any time
thereafter while such default continues and without further notice, at
Landlord's election, do any one or more of the following: (1) give Tenant
written notice stating that the Lease is terminated, effective upon the giving
of such notice or upon a date stated in such notice, as Landlord may elect, in
which event the Lease shall be irrevocably extinguished and terminated as stated
in such notice without any further action, or (2) with or without process of
law, in a lawful manner enter and repossess the Premises as of Landlord's former
estate, and expel Tenant and those claiming through or under Tenant, and remove
its and their effects, without being guilty of trespass, in which event the
Lease shall be irrevocably extinguished and terminated at the time of such
entry, or (3) pursue any other rights or remedies permitted by law. Any such
termination of the Lease shall be without prejudice to any remedies which might
otherwise be used for arrears of rent or prior breach of covenant, and in the
event of such termination Tenant shall remain liable under this Lease as
hereinafter provided. Tenant hereby waives all statutory rights (including,
without limitation, rights of redemption, if any) to the extent such rights may
be lawfully waived, and Landlord, without notice to Tenant, may store Tenant's
effects and those of any person claiming through or under Tenant at the expense
and risk of Tenant and, if Landlord so elects, may sell such effects at public
auction or private sale and apply the net proceeds to the payment of all sums
due to Landlord from Tenant, if any, and pay over the balance, if any, to
Tenant.

9.2 TENANT'S OBLIGATIONS AFTER TERMINATION.

     In the event that this Lease is terminated under any of the provisions
contained in Section 9.1 or shall be otherwise terminated for breach of any
obligation of Tenant, Tenant covenants to pay forthwith to Landlord, as
compensation, (i) the excess of the total rent reserved for the residue of the
Term over the rental value of the Premises for said residue of the Term and (ii)
the unamortized portion of the actual out-of-pocket costs and expenses incurred
by Landlord in completing Landlord's Work and fees and commissions paid to the
Broker, amortized on a straight-line reduction basis from 100% to 0% over the
Term of the Lease set forth in Section 1.1 hereof. In calculating the rent
reserved, there shall be included, in addition to the Annual Rent and all
additional rent, the value of all other consideration agreed to be paid or
performed by Tenant for said residue. Tenant further covenants as an additional
and cumulative obligation after any such ending to pay punctually to Landlord
all the sums and perform all the obligations which Tenant covenants in this
Lease to pay and to perform in the same manner and to the same extent and at the
same time as if this Lease had not been terminated. In calculating the amounts
to be paid by Tenant under the next foregoing covenant, Tenant shall be credited
with any amount paid to Landlord as compensation as provided in the first
sentence of this Section 9.2 and also with the net proceeds of any rents
obtained by Landlord by reletting the Premises, after deducting all Landlord's
expenses in connection with such reletting, including, without implied
limitation, all


                                       36



repossession costs, brokerage commissions, fees for legal services and expenses
of preparing the Premises for such reletting, it being agreed by Tenant that
Landlord may (i) relet the Premises or any part or parts thereof for a term or
terms which may at Landlord's option be equal to or less than or exceed the
period which would otherwise have constituted the balance of the Term and may
grant such concessions and free rent as Landlord in its sole judgment considers
advisable or necessary to relet the same and (ii) make such alterations, repairs
and decorations in the Premises as Landlord in its sole judgment considers
advisable or necessary to relet the same, and no action of Landlord in
accordance with the foregoing or failure to relet or to collect rent under
reletting shall operate or be construed to release or reduce Tenant's liability
as aforesaid.

     So long as at least 12 months of the Term remain unexpired at the time of
such termination, in lieu of any other damages or indemnity and in lieu of full
recovery by Landlord of all sums payable under all the foregoing provisions of
this Section 9.2, Landlord may by written notice to Tenant, at any time after
this Lease is terminated under any of the provisions contained in Section 9.1,
or is otherwise terminated for breach of any obligation of Tenant and before
such full recovery, elect to recover and Tenant shall thereupon pay, as
liquidated damages, an amount equal to the aggregate of the Annual Rent and
additional rent accrued under Article IV in the 12 months ended next prior to
such termination plus the amount of Annual Rent and additional rent of any kind
accrued and unpaid at the time of termination and less the amount of any
recovery by Landlord under the foregoing provisions of this Section 9.2 up to
the time of payment of such liquidated damages.

     Nothing contained in this Lease shall, however, limit or prejudice the
right of Landlord to prove and obtain in proceedings for bankruptcy or
insolvency by reason of the termination of this Lease, an amount equal to the
maximum allowed by any statute or rule of law in effect at the time when, and
governing the proceedings in which, the damages are to be proved, whether or not
the amount be greater, equal to, or less than the amount of the loss or damages
referred to above.


                                    ARTICLE X
                                  MISCELLANEOUS

10.1 NOTICE OF LEASE.

     Upon request of either party, both parties shall execute and deliver, after
the Term begins, a notice of this Lease in form appropriate for recording or
registration, and if this Lease is terminated before the Term expires, an
instrument in such form acknowledging the date of termination.


                                       37




10.2 RELOCATION.

     Landlord reserves the right to relocate the Premises no more than once
during the Term to comparable space within the Building, on or above the second
(2nd) floor of the Building and located on no more than two (2) consecutive
floors, by giving Tenant prior written notice of such intention to relocate. If
within thirty (30) days after receipt of such notice, Landlord and Tenant have
not agreed on the space to which the Premises are to be relocated and the timing
of such relocation, this Lease shall terminate on that date which is sixty (60)
days after the Tenant's receipt of such notice. If Landlord and Tenant do so
agree, then the Lease shall be deemed amended by deleting the description of the
original Premises and substituting thereof a description of such comparable
space. Landlord agrees that the relocated Premises shall have approximately the
same layout as the existing Premises and shall pay all reasonable out-of-pocket
relocation costs incurred by Tenant in relocating Tenant to such other space
within the Building, including, without limitation, all costs to rewire the
relocated Premises in a manner equivalent to the existing Premises.

10.3 NOTICES FROM ONE PARTY TO THE OTHER.

     All notices required or permitted hereunder shall be in writing and
addressed, if to the Tenant, at Tenant's Address or such other address as Tenant
shall have last designated by notice in writing to Landlord and, if to Landlord,
at Landlord's Address or such other address as Landlord shall have last
designated by notice in writing to Tenant. Any notice shall have been deemed
duly given if mailed to such address postage prepaid, registered or certified
mail, return receipt requested, when deposited with the U.S. Postal Service, or
if delivered to such address by hand, when so delivered.

10.4 BIND AND INURE.

     The obligations of this Lease shall run with the land, and this Lease shall
be binding upon and inure to the benefit of the parties hereto and their
respective successors and assigns, except that the Landlord named herein and
each successive owner of the Premises shall be liable only for the obligations
accruing during the period of its ownership. The obligations of Landlord shall
be binding upon the assets of Landlord which comprise the Building and the Lot
but not upon other assets of Landlord. No individual partner, member, trustee,
stockholder, officer, director, employee or beneficiary of Landlord shall be
personally liable under this Lease and Tenant shall look solely to Landlord's
interest in the Building and the Lot in pursuit of its remedies upon an event of
default hereunder, and the general assets of the individual partners, trustees,
stockholders, officers, employees or beneficiaries of Landlord shall not be
subject to levy, execution or other enforcement procedure for the satisfaction
of the remedies of Tenant.


                                       38




10.5 NO SURRENDER.

     The delivery of keys to any employee of Landlord or to Landlord's agent or
any employee thereof shall not operate as a termination of this Lease or a
surrender of the Premises.

10.6 NO WAIVER, ETC.

     The failure of Landlord to seek redress for violation of, or to insist upon
the strict performance of any covenant or condition of this Lease or any of the
Rules and Regulations referred to in Section 6.1.4, whether heretofore or
hereafter adopted by Landlord, shall not be deemed a waiver of such violation
nor prevent a subsequent act, which would have originally constituted a
violation, from having all the force and effect of an original violation, nor
shall the failure of Landlord to enforce any of said Rules and Regulations
against any other tenant in the Building be deemed a waiver of any such Rules or
Regulations. The receipt by Landlord of Annual Rent or additional rent with
knowledge of the breach of any covenant of this Lease shall not be deemed a
waiver of such breach by Landlord, unless such waiver be in writing and signed
by Landlord. No consent or waiver, express or implied, by Landlord to or of any
breach of any agreement or duty shall be construed as a waiver or consent to or
of any other breach of the same or any other agreement or duty.

10.7 NO ACCORD AND SATISFACTION.

     No acceptance by Landlord of a lesser sum than the Annual Rent and
additional rent then due shall be deemed to be other than on account of the
earliest installment of such rent due, nor shall any endorsement or statement on
any check or any letter accompanying any check or payment as rent be deemed as
accord and satisfaction, and Landlord may accept such check or payment without
prejudice to Landlord's right to recover the balance of such installment or
pursue any other remedy in this Lease provided.

10.8 CUMULATIVE REMEDIES.

     The specific remedies to which Landlord may resort under the terms of this
Lease are cumulative and are not intended to be exclusive of any other remedies
or means of redress to which it may be lawfully entitled in case of any breach
or threatened breach by Tenant of any provisions of this Lease. In addition to
the other remedies provided in this Lease, Landlord shall be entitled to the
restraint by injunction of the violation or attempted or threatened violation of
any of the covenants, conditions or provisions of this Lease or to a decree
compelling specific performance of any such covenants, conditions or provisions.


                                       39



10.9 LANDLORD'S RIGHT TO CURE.

     If Tenant shall at any time default in the performance of any obligation
under this Lease, Landlord shall have the right, but shall not be obligated, to
enter upon the Premises and to perform such obligation, notwithstanding the fact
that no specific provision for such substituted performance by Landlord is made
in this Lease with respect to such default. In performing such obligation,
Landlord may make any payment of money or perform any other act. All sums so
paid by Landlord (together with interest at the rate of 4% per annum in excess
of the then prime commercial rate of interest being charged by the three largest
national banks in Boston, Massachusetts) and all necessary incidental costs and
expenses in connection with the performance of any such act by Landlord, shall
be deemed to be additional rent under this Lease and shall be payable to
Landlord immediately on demand. Landlord may exercise the foregoing rights
without waiving any other of its rights or releasing Tenant from any of its
obligations under this Lease.

10.10 ESTOPPEL CERTIFICATE.

     Tenant agrees, from time to time, upon not less than 15 days' prior written
request by Landlord, to execute, acknowledge and deliver to Landlord a statement
in writing certifying that this Lease is unmodified and in full force and
effect; that Tenant has no defenses, offsets or counterclaims against its
obligations to pay the Annual Rent and additional rent and to perform its other
covenants under this Lease; that there are no uncured defaults of Landlord or
Tenant under this Lease (or, if there have been modifications, that this Lease
is in full force and effect as modified and stating the modifications, and, if
there are any defenses, offsets, counterclaims, or defaults, setting them forth
in reasonable detail); and the dates to which the Annual Rent, additional rent
and other charges have been paid. Any such statement delivered pursuant to this
Section 10.10 shall be in a form reasonably acceptable to and may be relied upon
by any prospective purchaser or mortgagee of premises which include the Premises
or any prospective assignee of any such mortgagee.

10.11 WAIVER OF SUBROGATION.

     Any insurance carried by either party with respect to the Premises and
property therein or occurrences thereon shall include a clause or endorsement
denying to the insurer rights of subrogation against the other party to the
extent rights have been waived by the insured prior to occurrences of injury or
loss. Each party, notwithstanding any provisions of this Lease to the contrary,
hereby waives any rights of recovery against the other for injury or loss due to
hazards covered by insurance containing such clause or endorsement to the extent
of the indemnification received thereunder.


                                       40




10.12 ACTS OF GOD.

     In any case where either party hereto is required to do any act, delays
caused by or resulting from Acts of God, war, civil commotion, fire, flood or
other casualty, labor difficulties, shortages of labor, materials or equipment,
government regulations, unusually severe weather, or other causes beyond such
party's reasonable control shall not be counted in determining the time during
which work shall be completed, whether such time be designated by a fixed date,
a fixed time or a "reasonable time," and such time shall be deemed to be
extended by the period of such delay.

10.13 BROKERAGE.

     Tenant and Landlord represent and warrant that they dealt with no brokers
in connection with this transaction other than the Broker and agree to defend,
with counsel approved by the other, indemnify and save the other harmless from
and against any and all cost, expense or liability for any compensation,
commissions or charges claimed by a broker or agent, other than the Broker in
connection with this Lease. Landlord hereby agrees to pay the brokerage fees to
the Broker in connection with the execution and delivery of this Lease.

10.14 SUBMISSION NOT AN OFFER.

     The submission of a draft of this Lease or a summary of some or all of its
provisions does not constitute an offer to lease or demise the Premises, it
being understood and agreed that neither Landlord nor Tenant shall be legally
bound with respect to the leasing of the Premises unless and until this Lease
has been executed by both Landlord and Tenant and a fully executed copy has been
delivered to each of them.

10.15 APPLICABLE LAW AND CONSTRUCTION.

     This Lease shall be governed by and construed in accordance with the laws
of The Commonwealth of Massachusetts. If any term, covenant, condition or
provision of this Lease or the application thereof to any person or
circumstances shall be declared invalid or unenforceable by the final ruling of
a court of competent jurisdiction having final review, the remaining terms,
covenants, conditions and provisions of this Lease and their application to
persons or circumstances shall not be affected thereby and shall continue to be
enforced and recognized as valid agreements of the parties, and in the place of
such invalid or unenforceable provision, there shall be substituted a like, but
valid and enforceable provision which comports to the findings of the aforesaid
court and most nearly accomplishes the original intention of the parties.


                                       41




     There are no oral or written agreements between Landlord and Tenant
affecting this Lease. This Lease may be amended, and the provisions hereof may
be waived or modified, only by instruments in writing executed by Landlord and
Tenant.

     The titles of the several Articles and Sections contained herein are for
convenience only and shall not be considered in construing this Lease.

     Unless repugnant to the context, the words "Landlord" and "Tenant"
appearing in this Lease shall be construed to mean those named above and their
respective heirs, executors, administrators, successors and assigns, and those
claiming through or under them respectively. If there be more than one tenant,
the obligations imposed by this Lease upon Tenant shall be joint and several.

10.16 AUTHORITY OF TENANT.

     Tenant represents and warrants to Landlord (which representations and
warranties shall survive the delivery of this Lease) that: (a) Tenant (i) is
duly organized, validly existing and in good standing under the laws of its
state of incorporation, (ii) has the corporate power and authority to carry on
businesses now being conducted and is qualified to do business in every
jurisdiction where such qualification is necessary and (iii) has the corporate
power to execute and deliver and perform its obligations under this Lease and
(b) the execution, delivery and performance by Tenant of its obligations under
this Lease have been duly authorized by all requisite corporate action and will
not violate any provision of law, any order of any court or other agency of
government, the corporate charter or by-laws of the Tenant or any indenture,
agreement or other instrument to which it is a party or by which it is bound.

                                   ARTICLE XI
                                SECURITY DEPOSIT

     Upon execution of the Lease, Tenant shall provide to Landlord at Tenant's
election either a cash deposit in the amount of $119,175.00, which amount shall
be increased to the amount of the Security Deposit prior to the payment to
Tenant of the Tenant Improvement Allowance in excess of such amount, or an
irrevocable, unconditional and transferable letter of credit in the amount of
$119,175.00, which amount shall be increased to the amount of the Security
Deposit prior to the payment to Tenant of the Tenant Improvement Allowance in
excess of such amount, and which letter of credit shall be issued by a bank or
other institution reasonably satisfactory to Landlord and in form and substance
reasonably satisfactory to Landlord, naming Landlord, its successors and assigns
as the beneficiary and expiring no less than one (1) month after the Term
Expiration Date or expiring not


                                       42



less than one (1) year after the Term Commencement Date and renewing
automatically each year (the "Letter of Credit"). Landlord shall be permitted to
draw upon the Letter of Credit in the event of (a) default by Tenant in any of
its obligations hereunder and the expiration of any applicable cure period, in
which event Landlord may draw upon all or a portion of the Letter of Credit and
apply the proceeds as described below, or (b) failure by Tenant to provide to
Landlord a replacement or substitute Letter of Credit in the amount of the
Security Deposit, and otherwise subject to the conditions set forth above, no
less than thirty (30) days prior to the expiration date of the Letter of Credit
then held by Landlord, in which event Landlord may draw upon all of the Letter
of Credit and hold the cash proceeds thereof as the Security Deposit hereunder.

     The Security Deposit is being delivered by Tenant to Landlord as security
for the faithful performance and observance by Tenant of the terms, provisions
and conditions of the Lease. If the Security Deposit is provided to Landlord in
cash, the Security Deposit shall be held in an account to be selected by
Landlord in its sole and absolute discretion, with no interest thereon to
Tenant. Landlord shall not have any obligation to segregate the Security Deposit
from other funds held by Landlord. Provided Tenant is not then in default under
the terms of the Lease and no default by Tenant has occurred which has not been
cured within thy applicable cure period, if any, the Security Deposit shall be
reduced (by a reduction in the amount of the Letter of Credit if the Security
Deposit is in the form of a Letter of Credit or the return of cash by Landlord
to Tenant if the Security Deposit is in the form of cash) to (a) $324,990.00 in
the 25th month of the Term of the Lease if Tenant demonstrates to Landlord's
reasonable satisfaction that Tenant has maintained liquid cash assets during
each of the four (4) immediately preceding consecutive calendar quarters of
$25,000,000 or more, or otherwise in the 37th month of the Term of the Lease,
(b) $162,495.00 in the 49th month of the Term of the Lease, and (c) zero in the
64th month of the Term of the Lease.

     Landlord shall have the right, but not the obligation, from time to time
without prejudice to any other remedy Landlord may have on account thereof, to
apply the Security Deposit or any portion thereof to Landlord's damages
resulting from any default by Tenant. If all or any part of the Security Deposit
is applied to an obligation of Tenant hereunder, Tenant shall immediately upon
request by Landlord restore the Security Deposit to the amount required prior to
such application. In the event Tenant has not restored the Security Deposit to
the required amount prior to a scheduled reduction in the amount of the Security
Deposit, as provided above, then no further reduction shall be permitted in the
amount of the Security Deposit hereunder. Tenant shall not have the right to
call upon Landlord to apply all or any part of the Security Deposit to cure any
default or fulfill any obligation of Tenant, but such use shall be solely in the
discretion of Landlord. Upon conveyance by Landlord of its interest under this
Lease, the Security Deposit may be delivered by Landlord to Landlord's grantee
or transferee. Upon any such delivery, Tenant hereby releases


                                       43



Landlord herein named of any and all liability with respect to the Security
Deposit, its application and return, and Tenant agrees to look solely to such
grantee or transferee. It is further understood that this provision shall also
apply to subsequent grantees and transferees.

     EXECUTED as a sealed instrument in two or more counterparts on the day and
year first above written.

                                    LANDLORD:


                                    CambridgePark Two Limited Partnership


                                    By: Its Agent: Spaulding and Slye Services
                                        Limited Partnership


                                        By: /s/ Andy Tsao
                                            ------------------------------------
                                            Andy Tsao
                                            Vice President


                                     TENANT:

                                     Allaire Corporation


                                     By: /s/ David A. Gerth
                                         ---------------------------------------
                                         Name: David A. Gerth
                                         Title: Chief Financial Officer
                                         Hereunto duly authorized




                                       44




                                   EXHIBIT A

         That certain parcel of land with buildings thereon situated in
Cambridge, Middlesex County, Massachusetts, shown as Lot A on a plan entitled 
"Subdivision Plan of Land Cambridge, Mass." Scale 1" - 60', dated February 27,
1985, prepared by Harry R. Feldman, Inc. recorded with Middlesex South Registry 
of Deeds as Plan No. 1038 of 1985 more particularly bounded and described as 
follows:

     Northerly by CambridgePark Drive, four hundred seventy-three and 70/100
(473.70) feet;

     Easterly by Lot B as shown on said plan, two hundred sixty-two and 50/100
(262.50) feet;

     Southerly by said Lot B, sixteen and 70/100 (16.70) feet;

     Easterly again by said Lot B, one hundred ten (110.00) feet; 

     Southerly again by said Lot B, by three lines of two hundred twenty-two 
and 24/100 (222.24) feet, two hundred eighteen and 12/100 (218.12) feet and 
twenty-three and 28/100 (23.28) feet; and

     Westerly by said Lot B, two hundred ninety-five and 15/100 (295.15) feet.

     Containing according to said plan 158,215 square feet.








                                   EXHIBIT B-1

             [Schematic drawing of Third Floor -- 150 CambridgePark]






                                   EXHIBIT B-2

            [Schematic drawing of Second Floor -- 150 CambridgePark]








                                    EXHIBIT C

                             (Intentionally Omitted)







                                    EXHIBIT D
                               LANDLORD'S SERVICES

I.   CLEANING

     A. General

        1.  All cleaning work will be performed between 8 a.m. and 12 midnight,
            Monday through Friday, unless otherwise necessary for stripping,
            waxing, etc.

        2.  Abnormal waste removal (e.g., computer installation paper, bulk
            packaging, wood or cardboard crates, refuse from cafeteria
            operation, etc.) shall be Tenant's responsibility.

     B. Daily Operations (5 times per week)

        1.  Tenant Areas

            a.  Empty and clean all waste receptacles; wash receptacles as
                necessary.

            b.  Vacuum all rugs and carpeted areas.

            c.  Empty, damp-wipe and dry all ashtrays.

        2.  Lavatories

            a.  Sweep and wash floors with disinfectant.
        
            b.  Wash both sides of toilet seats with disinfectant.

            c.  Wash all mirrors, basins, bowls, urinals.

            d.  Spot clean toilet partitions.

            e.  Empty and disinfect sanitary napkin disposal receptacles. 

            f.  Refill toilet tissue, towel, soap, and sanitary napkin
                dispensers.

        3.  Public Areas

            a.  Wipe down entrance doors and clean glass (interior and
                exterior).

            b.  Vacuum elevator carpets and wipe down doors and walls.

            c.  Clean water coolers.

     C. Operations as Needed (but not less than every other day)

        1.  Tenant and Public Areas

            a.  Buff all resilient floor areas.

     D. Weekly Operations

        1.  Tenant Areas, Lavatories, Public Areas

            a.  Hand-dust and wipe clean all horizontal surfaces with treated
                cloths to include furniture, office equipment, window sills,
                door ledges, chair rails, baseboards, convector tops, etc.,
                within normal reach.

            b.  Remove finger marks from private entrance doors, light switches,
                and doorways.

            c.  Sweep all stairways.


                                       D-1





     E. Monthly Operations

        1.  Tenant and Public Areas

            a.  Thoroughly vacuum seat cushions on chairs, sofas, etc.

            b.  Vacuum and dust grillwork.

        2.  Lavatories

            a.  Wash down interior walls and toilet partitions.

     F. As Required and Weather Permitting

        1.  Entire Building

            a.  Clean inside of all windows.

            b.  Clean outside of all windows.

     G. Yearly

        1.  Public Areas

            a.  Strip and wax all resilient tile floor areas.

II.   HEATING, VENTILATING, AND AIR CONDITIONING

        1.  Heating, ventilating, and air conditioning as required to provide
            reasonably comfortable temperatures for normal occupancy in
            accordance with minimum ASHRAE standards and requirements for normal
            business day occupancy (excepting holidays); Monday through Friday
            from 8:00 a.m. to 6:00 p.m. and Saturday from 8:00 a.m. to 1:00 p.m.

        2.  Maintenance of any additional or special air conditioning equipment
            and the associated operating cost will be at Tenant's expense, which
            is estimated at $50 per hour.

III.  WATER

            Hot water for lavatory purposes and cold water for drinking,
            lavatory and toilet purposes, and cold water for tenant's kitchen
            and tenant's hot water heater (tenant is to supply hot water
            heater).

IV.   ELEVATORS (if Building is Elevatored)

            Elevators for the use of all tenants and the general public for
            access to and from all floors of the Building. Programming of
            elevators (including, but not limited to, service elevators) shall
            be as Landlord from time to time determines best for the Building as
            a whole.

V.    RELAMPING OF LIGHT FIXTURES

            Tenant will reimburse Landlord for the cost of lamps, ballasts and
            starters and the cost of replacing same within the Premises.

VI.   CAFETERIA AND VENDING INSTALLATIONS


                                       D-2






     1.   Any space to be used primarily for lunchroom or cafeteria operation
          shall be Tenant's responsibility to keep clean and sanitary, it being
          understood that Landlord's approval of such use must be first obtained
          in writing.

     2.   Vending machines or refreshment service installations by Tenant must
          be approved by Landlord in writing and shall be restricted in use to
          employees and business callers. All cleaning necessitated by such
          installations shall be at Tenant's expense.

VII. ELECTRICITY

     A.   Landlord, at Landlord's expense, shall furnish electrical energy
          required for lighting, electrical facilities, equipment, machinery,
          fixtures, and appliances used in or for the benefit of Premises, in
          accordance with the provisions of the Lease of which this Exhibit is
          part.

     B.   Tenant shall not, without prior written notice to Landlord in each
          instance, connect to the Building electric distribution system any
          fixtures, appliances or equipment other than normal office machines
          such as personal computers, desk-top calculators and typewriters, or
          any fixtures, appliances or equipment which Tenant on a regular basis
          operates beyond normal building operating hours. In the event of any
          such connection, Tenant agrees to an increase in the ANNUAL ESTIMATED
          ELECTRICAL COST TO THE PREMISES and a corresponding increase in Annual
          Rent by an amount which will reflect the cost to Landlord of the
          additional electrical service to be furnished by Landlord, such
          increase to be effective as of the date of any such installation. If
          Landlord and Tenant cannot agree thereon, such amount shall be
          conclusively determined by a reputable independent electrical engineer
          or consulting firm to be selected by Landlord and paid equally by both
          parties, and the cost to Landlord will be included in Landlord's
          Operating Costs provided in Section 4.2 hereof.

     C.   Tenant's use of electrical energy in the Premises shall not at any
          time exceed the capacity of any of the electrical conductors or
          equipment in or otherwise serving Tenant's Space. In order to insure
          that such capacity is not exceeded and to avert possible adverse
          effect upon the Building electric service, Tenant shall not, without
          prior written notice to Landlord in each instance, connect to the
          Building electric distribution system any fixtures, appliances or
          equipment which operate on a voltage in excess of 120 volts nominal or
          make any alteration or addition to the electric system of Tenant's
          Space. Unless Landlord shall reasonably object to the connection of
          any such fixtures, appliances or equipment, all additional risers or
          other equipment required therefor shall be provided by Landlord, and
          the cost thereof shall be paid by Tenant upon Landlord's demand. In
          the event of any such connection, Tenant agrees to an increase in the
          ANNUAL ESTIMATED


                                       D-3





          ELECTRICAL COST TO THE PREMISES, such increase to be effective as of
          the date of any such connection. If Landlord and Tenant cannot agree
          thereon, such amount shall be conclusively determined by a reputable
          independent electrical engineer or consulting firm to be selected by
          Landlord and paid equally by both parties, and the cost to Landlord
          will be included in Landlord's Operating Costs provided in Section 4.2
          hereof.

     D.   If at any time after the date of this Lease, the rates at which
          Landlord purchases electrical energy from the public utility supplying
          electric service to the Building, or any charges incurred or taxes
          payable by Landlord in connection therewith, shall be increased or
          decreased, the ANNUAL ESTIMATED ELECTRICAL COST TO THE PREMISES shall
          be increased or decreased, as the case may be, by an amount equal to
          the estimated increase or decrease, as the case may be, in Landlord's
          cost of furnishing the electricity referred to in Paragraph A above as
          a result of such increase or decrease in rates, charges, or taxes. If
          Landlord and Tenant cannot agree thereon, such amount shall be
          conclusively determined by a reputable independent electrical engineer
          or consulting firm to be selected by Landlord and paid equally by both
          parties, and the cost to Landlord will be included in Landlord's
          Operating Costs as provided in Section 4.2 hereof. Any such increase
          or decrease shall be effective as of the date of the increase or
          decrease in such rate, charge or taxes.

     E.   Landlord may, at any time, elect to discontinue the furnishing of
          electrical energy. In the event of any such election by Landlord: (1)
          Landlord agrees to give reasonable advance notice of any such
          discontinuance to Tenant; (2) Landlord agrees to permit Tenant to
          receive electrical service directly from the public utility supplying
          service to the Building and to permit the existing feeders, risers,
          wiring and other electrical facilities serving the Premises to be used
          by Tenant and/or such public utility for such purpose to the extent
          they are suitable and safely capable; (3) Landlord agrees to pay such
          charges and costs, if any, as such public utility may impose in
          connection with the installation of Tenant's meters and to make or, at
          such public utility's election, to pay for such other installations as
          such public utility may require, as a condition of providing
          comparable electrical service to Tenant; and (4) Tenant shall
          thereafter pay, directly to the utility furnishing the same, all
          charges for electrical services to the Premises.


                                       D-4





                                    EXHIBIT E
                              RULES AND REGULATIONS

     The following rules and regulations have been formulated for the safety and
well-being of all tenants of the Building and to insure compliance with
governmental and other requirements. Strict adherence to these rules and
regulations is necessary to guarantee that each and every tenant will enjoy a
safe and undisturbed occupancy of its premises in the Building. Any continuing
violation of these rules and regulations by Tenant shall constitute a default by
Tenant under the Lease.

     Landlord may, upon request of any tenant, waive the compliance by such
tenant of any of the following rules and regulations, provided that (i) no
waiver shall be effective unless signed by Landlord's authorized agent, (ii) any
such waiver shall not relieve such tenant from the obligation to comply with
such rule or regulation in the future unless otherwise agreed to by Landlord,
(iii) no waiver granted to any tenant shall relieve any other tenant from the
obligation of complying with these rules and regulations, unless such other
tenant has received a similar written waiver from the Landlord, and (iv) any
such waiver shall not relieve Tenant from any liability to Landlord for any loss
or damage occasioned as a result of Tenant's failure to comply with any rule or
regulation

     1.   The entrances, lobbies, passages, corridors, elevators, halls, courts,
          sidewalks, vestibules, and stairways shall not be encumbered or
          obstructed by Tenant, Tenant's agents, servants, employees, licensees
          or visitors or used by them for any purposes other than ingress or
          egress to and from the Premises. Landlord shall have the right to
          control and operate portions of the Building and the facilities
          furnished for common use of the tenants in such manner as Landlord
          deems best for the benefit of the tenants generally.

     2.   The moving in or out of all safes, freight, furniture, or bulky matter
          of any description shall take place during the hours which Landlord
          may determine from time to time. Landlord reserves the right to
          inspect all freight and bulky matter to be brought into the Building
          and to exclude from the Building all freight and bulky matter which
          violates any of these Rules and Regulations or the Lease of which
          these Rules and Regulations are a part. Landlord reserves the right to
          have Landlord's structural engineer review Tenant's floor loads on the
          Premises at Tenant's expense.

     3.   Tenant, or the employees, agents, servants, visitors or licensees of
          Tenant shall not at any time place waste or discard any rubbish,
          paper,


                                       E-1





          articles, or objects of any kind whatsoever outside the doors of the
          Premises or in the corridors or passageways of the Building. No
          animals or birds shall be brought or kept in or about the Building.
          Bicycles shall not be permitted in the Building; provided that
          Landlord shall supply outdoor bicycle racks where bicycles may be
          secured.

     4.   Tenant shall not place objects against glass partitions or doors or
          windows or adjacent to any common space which would be unsightly from
          the Building corridors or from the exterior of the Building and will
          promptly remove the same upon notice from Landlord.

     5.   Tenant shall not make noises, cause disturbances, create vibrations,
          odors (other than ordinarily acceptable tenant kitchen odors in the
          building) or noxious fumes or use or operate any electric or
          electrical devices or other devices that emit sound waves or are
          dangerous to other tenants and occupants of the Building or that would
          interfere with the operation of any device or equipment or radio or
          television broadcasting or reception from or within the Building or
          elsewhere, or with the operation of roads or highways in the vicinity
          of the Building, and shall not place or install any projections,
          antennae, aerials, or similar devices inside or outside of the
          Premises, without the prior written approval of Landlord.

     6.   Tenant may not (without Landlord's approval therefor, which approval
          will be signified on Tenant's Plans submitted pursuant to the Lease)
          and Tenant shall not permit or suffer anyone to: (a) cook in the
          Premises except as accessory to the use of a coffee room/kitchenette
          containing a microwave oven; (b) place vending or dispensing machines
          of any kind in or about the Premises; (c) at any time sell, purchase
          or give away, or permit the sale, purchase, or gift of food in any
          form.

     7.   Tenant shall not: (a) use the Premises for lodging, manufacturing or
          for any immoral or illegal purposes; (b) use the Premises to engage in
          the manufacture or sale of, or permit the use of spirituous,
          fermented, intoxicating or alcoholic beverages on the Premises; (c)
          use the Premises to engage in the manufacture or sale of, or permit
          the use of, any illegal drugs on the Premises.

     8.   No awning or other projections (including antennae) shall be attached
          to the outside walls or windows. No curtains, blinds, shades, screens
          or signs other than those furnished by Landlord shall be attached to,
          hung in, or used in connection with any window or door of the Premises
          without prior written consent of Landlord.


                                       E-2




     9.   No signs, advertisement, object, notice or other lettering shall be
          exhibited, inscribed, painted or affixed on any part of the outside or
          inside of the Premises if visible from outside of the Premises.
          Interior signs on doors shall be painted or affixed for Tenant by
          Landlord or by sign painters first approved by Landlord at the expense
          of Tenant and shall be of a size, color and style acceptable to
          Landlord.

     10.  Tenant shall not use the name of the Building or use pictures or
          illustrations of the Building in advertising or other publicity
          without prior written consent of Landlord. Landlord shall have the
          right to prohibit any advertising by Tenant which, in Landlord's
          opinion, tends to impair the reputation of the Building or its
          desirability for offices, and upon written notice from Landlord,
          Tenant will refrain from or discontinue such advertising.

     11.  Door keys for doors in the Premises will be furnished at the
          Commencement of the Lease by Landlord. Tenant shall not affix
          additional locks on doors and shall purchase duplicate keys only from
          Landlord and will provide to Landlord the means of opening of safes,
          cabinets, or vaults left on the Premises. In the event of the loss of
          any keys so furnished by Landlord, Tenant shall pay to Landlord the
          cost thereof. Each tenant shall, upon the termination of its tenancy,
          restore to Landlord all keys of offices, storage and toilet rooms
          either furnished to, or otherwise procured by, such tenant.

     12.  Tenant shall cooperate and participate in all security programs
          affecting the Building.

     13.  Tenant assumes full responsibility for protecting its space from
          theft, robbery and pilferage, which includes keeping doors locked and
          other means of entry to the Premises closed and secured.

     14.  Tenant shall not make any room-to-room canvass to solicit business
          from other tenants in the Building, and shall not exhibit, sell or
          offer to sell, use, rent or exchange any item or services in or from
          the Premises unless ordinarily embraced within Tenant's use of the
          Premises as specified in its Lease. Canvassing, soliciting and
          peddling in the Building are prohibited and Tenant shall cooperate to
          prevent the same. Peddlers, solicitors and beggars shall be reported
          to the Management Office.

     15.  Tenant shall not mark, paint, drill into, or in any way deface any
          part of the Building or Premises. No boring, driving of nails or
          screws (except for picture hanging, etc.), cutting or stringing of
          wires shall be


                                       E-3




          permitted, except with the prior written consent of Landlord, and as
          Landlord may direct. Tenant shall not construct, maintain, use or
          operate within their respective premises any electrical device, wiring
          or apparatus in connection with a loud speaker system or other sound
          system, except as reasonably required as part of a communication
          system approved in writing by Landlord, prior to the installation
          thereof. Tenant shall not install any resilient tile or similar floor
          covering in the Premises except with the prior written approval of
          Landlord. The use of cement or other similar adhesive material is
          expressly prohibited.

     16.  Tenant shall not waste electricity or water and agrees to cooperate
          fully with Landlord to assure the most effective operation of the
          Building's heating and air conditioning and shall refrain from
          attempting to adjust controls. Tenant shall keep corridor doors closed
          except when being used for access.

     17.  The water and wash closets and other plumbing fixtures shall not be
          used for any purposes other than those for which they were
          constructed, and no sweepings, rubbish, rags, or other substances
          shall be thrown therein. All damage resulting from misuse of said
          fixtures shall be borne by the tenant who, or whose servant,
          employees, agents, licensees, invitees, customers or guests shall have
          caused the same.

     18.  Building employees shall not be required to perform, and shall not be
          requested by any tenant or occupant to perform, any work outside of
          their regular duties, unless under specific instructions from the
          office of the Managing Agent of the Building. The requirements of
          tenants will be attended to only upon application to Landlord, and any
          special requirements shall be billed to Tenant (and paid when the next
          installment of rent is due) in accordance with the schedule of charges
          maintained by Landlord from time to time or at such charge as is
          agreed upon in advance by Landlord and Tenant.

     19.  Tenant may request heating and/or air conditioning during other
          periods in addition to normal working hours by submitting its request
          in writing to the office of the Managing Agent of the Building no
          later than 2:00 p.m. the preceding work day (Monday through Friday) on
          forms available from the office of the Managing Agent. The request
          shall clearly state the start and stop hours of the "off-hour"
          service. Tenant shall submit to the Building Manager a list of
          personnel authorized to make such request. The Tenant shall be charged
          for such operation in the form of additional rent; such charges are to
          be


                                       E-4




          determined by the Managing Agent and shall be fair and reasonable and
          reflect the additional operating costs involved.

     20.  Tenant covenants and agrees that its use of the Premises shall not
          cause a discharge of more than the gallonage per foot of Premises
          Design Floor Area per day of sanitary (non-industrial) sewage allowed
          under the sewage discharge permit for the Building. Discharges in
          excess of that amount, and any discharge of industrial sewage, shall
          only be permitted if Tenant, at its sole expense, shall have obtained
          all necessary permits and licenses therefor, including without
          limitation permits from state and local authorities having
          jurisdiction thereof. Tenant shall submit to Landlord on December 31
          of each year of the Term of this Lease a statement, certified by an
          authorized officer of Tenant, which contains the following
          information: name of all chemicals, gases, and hazardous substances,
          used, generated, or stored on the Premises; type of substance (liquid,
          gas or granular); quantity used, stored or generated per year; method
          of disposal; permit number, if any, attributable to each substance,
          together with copies of all permits for such substances; and permit
          expiration date for each substance. No flammable, combustible or
          explosive fluid, chemical or substance shall be brought into or kept
          upon the Premises, the Building or the Lot (other than those fluids or
          chemicals customarily used by tenants of other first-class office
          buildings in connection with office purposes and then only those types
          and quantities permitted under Landlord's policies of insurance for
          the Building).

     21.  Landlord reserves the right to exclude from the Building at all times
          any person who is not known or does not properly identify himself to
          the Building management. Landlord may, at its option, require all
          persons admitted to or leaving the Building between the hours of 6:00
          p.m. and 8:00 a.m., Monday through Friday, and at any hour on
          Saturdays, Sundays and legal holidays, to register. Each tenant shall
          be responsible for all persons for whom it authorizes entry into the
          Building, and shall be liable to Landlord for all acts or omissions of
          such persons.

     22.  Landlord reserves the right to inspect all freight to be brought into
          the Project and to exclude from the Project all freight which violates
          any of these rules and regulations. There shall not be used in any
          space or in the common halls of the Building, either by any tenant or
          by jobbers or others in the delivery or receipt of merchandise, any
          hand trucks, except those equipped with rubber tires and side guards.


                                       E-5