Exhibit 2.1
 
                        SENTRY PARK WEST OFFICE CAMPUS
                            BLUE BELL, PENNSYLVANIA

                          REAL ESTATE SALE AGREEMENT
                          --------------------------


     THIS REAL ESTATE SALE AGREEMENT (this "Agreement") is made as of the 25th
day of March, 1996, by and between SENTRY WEST JOINT VENTURE, an Illinois joint
venture partnership ("Seller"), with an office at Two North Riverside Plaza,
Suite 600, Chicago, Illinois 60606 and BGK PROPERTIES, INC., a Delaware
corporation ("Purchaser"), with an office at 330 Garfield Street, Suite 200,
Santa Fe, New Mexico 87501.

                                   RECITALS

     A. Seller is the owner of a certain parcel of real estate (the "Real
Property") commonly known as 1777 Sentry Parkway West in the City of Blue Bell,
County of Montgomery, Commonwealth of Pennsylvania, which parcel is more
particularly described in attached Exhibit A, and upon which is located a five
(5) building office development commonly known as "Sentry Park West".

     B. Seller desires to sell to Purchaser, and Purchaser desires to purchase
from Seller, the "Property" (as such term is hereinafter defined), each in
accordance with and subject to the terms and conditions set forth in this
Agreement.

     THEREFORE, in consideration of the above Recitals, the mutual covenants and
agreements herein set forth and the benefits to be derived therefrom, and other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Purchaser and Seller agree as follows:

     1.  PURCHASE AND SALE

     Subject to and in accordance with the terms and conditions set forth in
this Agreement, Purchaser shall purchase from Seller and Seller shall sell to
Purchaser the Real Property, together with: (i) all buildings and improvements
owned by Seller and any and all of Seller's rights, easements, licenses and
privileges presently thereon or appertaining thereto; (ii) Seller's right, title
and interest in and to the leases (the "Leases") affecting the Property or any
part thereof; (iii) the interest of Seller in all security deposits held by
Seller that have been paid by tenants under the Leases and not applied by Seller
in accordance with the terms of the Leases and/or applicable law, if any (the
"Security Deposits); (iv) all accrued but unpaid interest on the Security
Deposits owed by Seller pursuant to applicable law and/or a particular Lease, if
any ("Security Deposit Interest"); (v) all of the furniture, furnishings,
fixtures, equipment, maintenance vehicles, tools and other tangible personalty
owned by Seller, located on the Property and used in connection therewith that
are listed on Exhibit C attached hereto (the "Personal Property"); (vi) all
right, title and interest of Seller under those "Service Contracts" (as defined
in Section 10(A)(ii) below) that Purchaser elects to assume and/or is required
to assume in accordance with Section 11(M) below; (vii) if and to the extent
transferable, all

 
licenses and permits issued by governmental authorities relating to the use,
maintenance, occupancy or operation of the Property; all to the extent
applicable to the period from and after the "Closing" (as such term is
hereinafter defined) (items (i) through (vii) above, together with the Real
Property, are collectively referred to in this Agreement as the "Property"). All
of the foregoing expressly excludes all property owned by tenants or other users
or occupants of the Property except to the extent that any Security Deposits
and/or Security Deposit Interest are deemed to be "owned" by a tenant under
applicable law.

     2.  PURCHASE PRICE

     The purchase price to be paid by Purchaser to Seller for the Property is
Twelve Million Dollars ($12,000,000.00) (the "Purchase Price"). The Purchase
Price shall be paid as follows:

         A.  Earnest Money.

             (i)  Upon execution of this Agreement by Purchaser and Seller,
                  Purchaser shall deliver to Partners Title Company of Houston,
                  Texas ("Escrowee") initial earnest money (the "Initial Earnest
                  Money") in the sum of One Hundred Thousand Dollars
                  ($100,000.00) and Purchaser, Seller and Escrowee shall execute
                  a joint order escrow agreement in the form of Exhibit F
                  attached hereto. If Purchaser does not terminate this
                  Agreement pursuant to and in accordance with Section 8(A)
                  below, Purchaser shall, on or before the expiration of the
                  "Review Period" (as defined in Section 8(A) below), deposit
                  with the Escrowee additional earnest money (the "Additional
                  Earnest Money") in the sum of One Hundred Thousand Dollars
                  ($100,000.00). The Initial Earnest Money and, if deposited or
                  required to be deposited with the Escrowee, the Additional
                  Earnest Money, together with any interest earned thereon net
                  of investment costs, are referred to in this Agreement as the
                  "Earnest Money". The Earnest Money shall be invested as Seller
                  and Purchaser so direct. Any and all interest earned on the
                  Earnest Money shall be reported to Purchaser's federal tax
                  identification number.

             (ii) If the transaction closes in accordance with the terms of this
                  Agreement, at Closing, the Earnest Money shall be delivered by
                  Escrowee to Seller as part payment of the Purchase Price. If
                  the transaction fails to close due to a default on the part of
                  Purchaser, the Earnest Money shall be delivered by Escrowee to
                  Seller as liquidated and agreed upon damages in accordance
                  with Section 7(B) below. If the transaction fails to close due
                  to a default on the part of Seller, the Earnest Money shall be
                  delivered by Escrowee to Purchaser, and Purchaser shall have
                  the remedy provided for in Section 7(A) below.

         B. Cash at Closing. At Closing, Purchaser shall pay to Seller, by wire
transferred current federal funds, an amount equal to the Purchase Price, minus
the sum of the

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Earnest Money which Seller receives at Closing from the Escrowee, and plus or
minus, as the case may require, the closing prorations and adjustments to be
made pursuant to Section 4(C) below.

     3.   EVIDENCE OF TITLE

          A.   Title Commitment.

               Purchaser shall, within ten (10) days after the date of this
Agreement, obtain and cause to be delivered to Seller a current (that is,
effective within thirty (30) days prior to the date of this Agreement)
commitment for an ALTA Owner's Title Insurance Policy (the "Title Commitment"),
in the amount of the Purchase Price, issued by Partners Title Company of
Houston, Texas (as agent for Chicago Title Insurance Company) (the "Title
Insurer"). At Closing, the conveyance of the Property to Purchaser shall be made
subject only to those exceptions to title which are more fully described on
attached Exhibit B and exceptions to title which become Permitted Exceptions
pursuant to this Section 3 (collectively, the "Permitted Exceptions"), and
Purchaser shall be responsible at Closing for obtaining a later-dated title
commitment from the Title Insurer in the amount of the Purchase Price reflecting
the conveyance of the Property to Purchaser.

          B.   Survey.

          Seller shall, within thirty (30) days after the date of this
Agreement, deliver to Purchaser a survey (the "Survey") of the Real Property
prepared by a surveyor licensed in the Commonwealth of Pennsylvania in
accordance with the Minimum Standard Requirements for Land Title Surveys (as
jointly established and adopted in 1992 by the American Land Title Association
and American Congress on Surveying and Mapping) for an "Urban ALTA/ACSM Land
Title Survey" (as defined therein).

          C.   Review of Title Commitment and Survey.

               If the Title Commitment or Survey disclose exceptions to title
other than those Permitted Exceptions which are noted on attached Exhibit B,
then Purchaser shall have until 5:00 p.m. (Chicago, Illinois time) on the tenth
(10th) day after its receipt of the last of the Title Commitment and the Survey
within which to notify Seller of any such exceptions to title to which Purchaser
objects. If any additional exceptions to title arise between the date of the
Title Commitment, the Survey and the Closing, Purchaser shall have five (5) days
after its receipt of notice of same within which to notify Seller of any such
exceptions to title to which Purchaser objects. Any such exceptions to title not
objected to by Purchaser as aforesaid shall become Permitted Exceptions. If
Purchaser objects to any such exceptions to title, Seller shall have until
Closing (but in any event at least fifteen [15] days after it receives notice of
Purchaser's objection(s)) to remove such exceptions to title by waiver or
endorsement by the Title Insurer. If Seller fails to remove any such exceptions
to title as aforesaid, Purchaser may, as its sole and exclusive remedy,
terminate this Agreement and obtain a return of the Earnest Money. If Purchaser
does not elect to terminate this Agreement, Purchaser shall consummate the
Closing and accept title to the Property subject to all such exceptions to title
(in which event, all such exceptions to title shall be deemed "Permitted
Exceptions").

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     4.   CLOSING

          A. Closing Date. The "Closing" of the transaction contemplated by this
Agreement (that is, the payment of the Purchase Price, the transfer of title to
the Property, and the satisfaction of all other terms and conditions of this
Agreement) shall occur at 10 a.m. (Chicago, Illinois time) on the seventy-fifth
(75th) day after the date of this Agreement at the Chicago, Illinois office of
counsel for Seller, Rosenberg & Liebentritt, P.C., or at such other time and
place as Seller and Purchaser shall agree in writing. The "Closing Date" shall
be the date of Closing. If the date for Closing above provided for falls on a
Saturday, Sunday or legal holiday, then the Closing Date shall be the next
business day.

          B.   Closing Documents.

               (i) Seller. At Closing, Seller shall deliver to Purchaser the
                   following:

                   (a)  a special warranty deed (the "Deed"), subject to
                        Permitted Exceptions, and in form acceptable to the
                        Title Insurer;

                   (b)  a "special" or "limited" warranty bill of sale (the
                        "Bill of Sale") sufficient to transfer to Purchaser
                        title to the Personal Property in its "as is, where is"
                        condition and expressly disclaiming any warranties other
                        than as to title as aforesaid;

                   (c)  a letter advising tenants under the Leases of the change
                        in ownership of the Property, that all Security Deposits
                        and Security Deposit Interest transferred to Purchaser
                        at Closing (either by way of a credit against the
                        Purchase Price or, in the case of Security Deposits in
                        the form of a letter of credit or held in a segregated
                        bank account, by way of assignment to Purchaser at
                        Closing) are held by and are the responsibility of
                        Purchaser and directing the tenants to pay all payments
                        of rent during the period from and after the Closing
                        Date to Purchaser;

                   (d)  four (4) counterparts of an assignment and assumption of
                        the Leases, Security Deposits and Security Deposit
                        Interest in the form of Exhibit G attached hereto (the
                        "Lease Assignment"), executed by Seller;

                   (e)  four (4) counterparts of an assignment and assumption
                        of: (1) those "Terminable Service Contracts" (as defined
                        in Section 11(M) below) that Purchaser does not elect be
                        canceled in accordance with Section 11(M) below, and (2)
                        all "Required Service Contracts" (as defined in Section
                        11(M) below), such assignment and assumption to be in
                        the form of Exhibit H attached hereto (the "Service
                        Contract Assignment"), executed by Seller;

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                    (f)  an affidavit stating, under penalty of perjury,
                         Seller's U.S. taxpayer identification number and that
                         Seller is not a foreign person within the meaning of
                         Section 1445 of the Internal Revenue Code;

                    (g)  four (4) counterparts of a closing statement (the
                         "Closing Statement") to be executed by Seller and
                         Purchaser, containing the "Closing Delinquency
                         Schedule" (as defined below) and setting forth the
                         prorations and adjustments to the Purchase Price as
                         required by Section 4(C) below, executed by Seller;

                    (h)  all executed "Estoppel Certificates" (as hereinafter
                         defined) received by Seller as of the Closing Date;

                    (i)  four (4) counterparts of an assignment and assumption
                         of the "Sewer Easement Agreement" (as defined in
                         Section 11(R) below), the "Sewer Escrow Agreement" (as
                         defined in Section 11(R) below) and all of the other
                         documents set forth in items 9 through 20 on attached
                         Exhibit B, in the form of Exhibit M attached hereto
                         (the "Assignment and Assumption of Title Documents"),
                         executed by Seller; and

                    (j)  three (3) counterparts of the "Escrow Assumption
                         Letter" (as defined in Section 11(R) below), executed
                         on behalf of Seller and "R&L" (as defined in Section
                         11(R) below).

               (ii) Purchaser. Purchaser shall deliver or cause to be
                    delivered to Seller at Closing:

                    (a)  the funds required pursuant to Section 2(B) above;

                    (b)  four (4) counterparts of the Lease Assignment, executed
                         by Purchaser;

                    (c)  four (4) counterparts of the Service Contract
                         Assignment, executed by Purchaser;

                    (d)  four (4) counterparts of the Closing Statement,
                         executed by Purchaser;

                    (e)  copies of any executed Estoppel Certificates received
                         by Purchaser as of the Closing Date;

                    (f)  four (4) counterparts of the Assignment and Assumption
                         of Title Documents, executed by Purchaser;

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                    (g)  if required under Section 11(R) below, the "Substitute
                         Deed of Dedication" (as defined in Section 11(R)
                         below); and

                    (h)  three (3) counterparts of the Escrow Assumption Letter,
                         executed on behalf of Purchaser.

               C.   Closing Prorations and Adjustments.
                    
               (i)  The following items are to be prorated or adjusted (as
                    appropriate) as of the Closing Date, it being understood
                    that for purposes of prorations and adjustments, Seller
                    shall be deemed the owner of the Property on the day prior
                    to the Closing Date and Purchaser shall be deemed the owner
                    of the Property as of the Closing Date:

                    (a)  real estate and personal property taxes and assessments
                         (initially on the basis of the most recent
                         ascertainable tax bill if the current bill is not then
                         available and, in all events, subject to reproration as
                         described in Section 4(C)(iv) below);

                    (b)  water and sewer use charges, if any (initially on the
                         basis of the most recent periods for which the same
                         have been billed if the bill with respect to the period
                         through Closing is not then available and subject to
                         reproration as described in Section 4(C)(iii) below);

                    (c)  the "minimum" or "base" rent payable by tenants under
                         the Leases ("Base Rent"); provided, however, that rent
                         and all other sums which are due and payable to Seller
                         by any tenant but uncollected as of the Closing shall
                         not be adjusted, but Purchaser shall cause the rent and
                         other sums for the period prior to Closing to be
                         remitted to Seller if, as and when collected.  At
                         Closing, Seller shall deliver to Purchaser a schedule
                         (the "Closing Delinquency Schedule") of all such past
                         due but uncollected rent and other sums owed by tenants
                         (the "Past Due Rents"). Purchaser shall include the
                         amount of the Past Due Rents in the first bills
                         thereafter submitted to the tenants in question after
                         the Closing, and shall continue to do so for twelve
                         (12) months thereafter.  Purchaser shall promptly remit
                         to Seller any such Past Due Rents paid by tenants set
                         forth on the Closing Delinquency Schedule, but only if
                         a deficiency in the then current rent is not thereby
                         created. To the extent not set forth on the Closing
                         Delinquency Schedule, overage rent and reimbursement of
                         real estate taxes payable, common area maintenance,
                         utility charges, water and sewer charges, insurance and
                         all other charges 

                                       6

 
                         to or contributions by tenants under the Leases other
                         than Base Rent (collectively, the "Operating Expense
                         Reimbursements") shall be prorated as follows: the
                         amount of any Base Rents and Operating Expense
                         Reimbursements to be paid by any tenant shall be paid
                         in accordance with such tenant's Lease as now existing
                         (Purchaser hereby covenanting and agreeing not to
                         modify the Leases after Closing to change the date
                         and/or method for payment of such amounts until after
                         the occurrence of the reprorations described in
                         Sections 4(C)(iii) and 4(C)(iv) below) and Purchaser
                         shall, after Closing, promptly pay to Seller a prorata
                         portion of such Operating Expense Reimbursement, based
                         upon apportionment being made as of the Closing Date,
                         promptly after the date when such Operating Expense
                         Reimbursement is received from the tenant;

                    (d)  with respect to tenant improvement costs and/or
                         allowances or leasing commissions relating to (1) "New
                         Leases" (as hereinafter defined) executed after the
                         date of this Agreement and prior to the end of the
                         "Review Period" (as hereinafter defined), and (2) New
                         Leases executed during the period between the
                         expiration of the Review Period and Closing with the
                         consent of Purchaser granted (or deemed to be granted)
                         in accordance with Section 11(L) below, Seller and
                         Purchaser agree that such costs, allowances and
                         commissions shall be prorated over the term of any such
                         New Lease with Seller being responsible for a portion
                         of such costs, allowances and commissions based on the
                         ratio of base rent payments received by Seller through
                         the Closing Date to the total base rent payable over
                         the term of the particular New Lease and, in the event
                         that Seller has paid such costs, allowances and/or
                         commissions prior to Closing, Purchaser shall reimburse
                         Seller at Closing for a prorata portion of the amount
                         of any such costs, allowances and/or commissions paid
                         by Seller, based on the above-described proration.

                    (e)  the amount of the Security Deposits and Security
                         Deposit Interest held by Seller as of the Closing Date,
                         if any, with Purchaser receiving a credit at Closing
                         against the Purchase Price in the amount of the
                         Security Deposits and Security Deposit Interest held by
                         Seller as of the Closing Date, if any;

                    (f)  to the extent not included in the amounts prorated in
                         Section 4(C)(i)(b) above, water, electric, telephone
                         and all other utility and fuel charges, fuel on hand
                         (at cost plus sales tax), and any deposits with utility
                         companies (to the 

                                       7

 
                         extent possible, utility prorations
                         will be handled by meter readings on the day
                         immediately preceding the Closing Date);

                    (g)  amounts due and prepayments under the Service
                         Contracts;

                    (h)  assignable license and permit fees; and

                    (i)  other similar items of income and
                         expenses of operation.

             (ii)   Notwithstanding any other provision of this Section 4(C),
                    Seller shall in all events be entitled to retain Operating
                    Expense Reimbursements paid by tenants for real estate taxes
                    and assessments, common area maintenance expenses, utility
                    charges, water and sewer charges, insurance and all other
                    costs and expenses charged to tenants under the Leases as of
                    the Closing to the extent not in excess of such taxes,
                    assessments, charges and expenses paid by Seller (whether by
                    direct payment of such amounts in cash by Seller or by
                    credit given by Seller to Purchaser at Closing) for the
                    period prior to the Closing Date.

             (iii)  As soon as practical after Closing, but in no event later
                    than March 31, 1997, Seller and Purchaser shall, with
                    respect to any amounts prorated or adjusted at Closing
                    pursuant to Section 4(C)(i) above based on estimates or
                    formulae, as applicable (other than real estate and personal
                    property taxes and assessments, which shall be reprorated in
                    accordance with Section 4(C)(iv) below), jointly determine
                    and reapportion such amounts in accordance with Section
                    4(C)(i) above upon determination of the actual costs or
                    expenses with respect thereto.  In the event that the amount
                    credited to Purchaser by Seller at Closing exceeds the
                    amount of the credit that Purchaser should have received had
                    such actual amounts been available at Closing, Purchaser
                    shall promptly remit such excess amount to Seller.  In the
                    event that:  (1) the amount credited to Seller by Purchaser
                    at Closing exceeds the amount of the credit that Seller
                    should have received at Closing had such actual amounts been
                    available at Closing; and/or (2) the amount of the Operating
                    Expense Reimbursements with respect to such amounts retained
                    by Seller at Closing exceed the amount of the Operating
                    Expense Reimbursements that Seller should have retained at
                    Closing had such actual amounts been available at Closing,
                    Seller shall promptly remit such excess amounts to Purchaser
                    and, in the event that any portion of such excess amounts
                    are refundable to tenants under any of the Leases, Purchaser
                    shall be thereafter obligated to promptly remit such portion
                    to the particular tenants in question (and Purchaser shall
                    indemnify, defend and hold Seller, its partners, and their
                    respective directors, officers, employees 

                                       8

 
                    and agents, and each of them, harmless from and against any
                    losses, claims, damages and liabilities [including, without
                    limitation, reasonable attorneys' fees and expenses incurred
                    in connection therewith] arising out of or resulting from
                    Purchaser's failure to remit such amounts to the tenants in
                    accordance with this Section 4(C)(iii) and Section 4(C)(iv)
                    below).

               (iv) Seller is currently seeking a reduction of the assessed
                    value of the Property for real estate tax purposes with
                    respect to all tax years commencing in 1993 through 1996 and
                    a corresponding reduction in real estate taxes payable with
                    respect to all tax years commencing in 1993 through 1996.
                    Purchaser and Seller hereby agree that: (1) Seller shall,
                    after Closing, maintain control of the real estate tax
                    appeal and reduction process with respect to all tax years
                    commencing in 1993 through 1996 and shall have the right to
                    engage counsel, consultants, expert witnesses and appraisers
                    as Seller shall reasonably determine to be necessary to such
                    appeal and Purchaser shall cooperate (and cause its counsel
                    to cooperate) with Seller with respect to such process; (2)
                    Seller shall be responsible for the cost of any counsel,
                    consultant, expert witness or appraiser employed by Seller
                    to obtain any reduction of real estate taxes for tax years
                    commencing in 1993 through 1995; (3) Purchaser and Seller
                    shall each be responsible for a portion of the cost of any
                    counsel, consultant, expert witness or appraiser employed by
                    Seller to obtain any reduction of real estate taxes for tax
                    years commencing in 1996, with apportionment being made
                    based on their respective periods of ownership; and (4)
                    Seller and Purchaser shall reprorate real estate and
                    personal property taxes (which were approximated at Closing
                    pursuant to Section 4(C)(i)(a) above based on the most
                    recent ascertainable tax bills) and the Operating Expense
                    Reimbursements received from tenants with respect to such
                    taxes upon issuance of the final real estate and personal
                    property tax bills for the tax years in which the Closing
                    occurs. If, after the reproration described in item (4) of
                    this Section 4(C)(iv), the amount credited to Purchaser by
                    Seller at Closing exceeds the amount of the credit that
                    Purchaser should have received had such actual amounts been
                    available at Closing, Purchaser shall promptly remit such
                    excess amount to Seller. If, after the reproration described
                    in item (4) of this Section 4(C)(iv): (x) the amount
                    credited to Seller by Purchaser at Closing with respect to
                    such taxes exceeds the amount of the credit that Seller
                    should have received at Closing had such actual amounts been
                    available at Closing; and/or (y) the amount of the Operating
                    Expense Reimbursements with respect to such taxes retained
                    by Seller at Closing exceed the amount of the Operating
                    Expense Reimbursements that Seller should have retained at
                    Closing with respect to such taxes had the actual amount of
                    such taxes been available at Closing, Seller shall promptly
                    remit such excess amounts to Purchaser and, in the event
                    that any portion of such



                                       9

 
                    excess amounts are refundable to tenants under any of the
                    Leases, Purchaser shall be thereafter obligated to remit
                    such portion to the particular tenants in question.

               (v)  If Seller has not received all Past Due Rents within sixty
                    (60) days after the Closing Date, Seller at its sole cost
                    and expense, shall be entitled at any time within the twelve
                    (12) month period after such date to commence such actions
                    or proceedings not affecting possession or enforcing
                    landlord's liens or resulting in termination of the Lease in
                    question as Seller shall desire to collect any such Past Due
                    Rents, and Purchaser shall cooperate with Seller in any such
                    action.

               (vi) For purposes of this Section 4(C), the amount of any expense
                    credited by one party to the other shall be deemed an
                    expense paid by that party.  The terms and provisions of
                    this Section 4(C) shall survive Closing and the delivery of
                    the Deed.

          D.   Transaction Costs.
               ----------------- 

               Seller shall be responsible for and pay upon Closing one-half of
the amount of the transfer taxes owed in connection with the Deed (and Seller
and Purchaser shall timely execute and deliver such forms and returns as are
necessary in connection therewith). Purchaser shall be responsible for and pay
all other closing and transaction costs other than those costs to be paid by
Seller in accordance with the preceding sentence including, without limitation,
(1) one-half of the amount of the transfer taxes owed in connection with the
Deed, (2) the entire cost of the owner's title policy to be delivered to
Purchaser in accordance with the provisions of the marked-up title commitment
described in Section 3(A) above, (3) title insurance premiums for any
endorsements requested by Purchaser, (4) the entire cost of the Survey, (5)
recording charges, (6) Title Insurer's standard escrow fees, if any, (6) Title
Insurer's fee, if any, to perform a "New York Style" closing in which the Title
Insurer insures the "gap" period between the date of the most recent date down
of the title commitment and the Closing Date and issues a marked-up title
commitment at Closing, together with all other charges customarily paid by a
purchaser of improved real estate in the Commonwealth of Pennsylvania, whether
or not the Closing occurs. Seller and Purchaser shall, however, be responsible
for the fees of their respective attorneys.

          E.   Possession.
               ---------- 

               Upon Closing, Seller shall deliver to Purchaser possession of the
Property, subject to such matters as are permitted by or pursuant to this
Agreement.

     5.   CASUALTY LOSS AND CONDEMNATION
          ------------------------------

          If, prior to Closing, the Property or any part thereof shall be
condemned, or destroyed or damaged by fire or other casualty, Seller shall
promptly so notify Purchaser.  In such event, provided that either:  (i) the
reasonable cost to restore the Property due to such damage or destruction is
greater than Five Hundred Thousand and No/100 Dollars ($500,000.00), or (ii) any
portion of any of the office buildings located at the Property is taken and/or
condemned, or (iii) some other taking and/or condemnation materially, adversely
affects the value of the Property 



                                       10

 
(items (ii) and (iii) are collectively referred to hereinafter as a "Material
Condemnation"), then either Seller or Purchaser shall have the option to
terminate this Agreement by delivery of its written termination notice to the
other within fifteen (15) days after Seller's delivery to Purchaser of its
notice of a Material Condemnation or the occurrence of a casualty loss. If (a)
the reasonable cost to restore the Property due to the aforementioned damage or
destruction is less than or equal to Five Hundred Thousand Dollars
($500,000.00), (b) the afore-mentioned taking and/or condemnation is not a
Material Condemnation, or (c) neither Seller nor Purchaser elects to terminate
this Agreement pursuant to the provisions of the preceding sentence (time being
of the essence with respect to any such election), then Seller and Purchaser
shall consummate the transaction contemplated by this Agreement without
abatement of the Purchase Price for any amounts other than any deductible
amounts payable by Seller under applicable policies of insurance and Purchaser
shall be entitled during the period following the "Review Period" (as
hereinafter defined) and prior to Closing to approve the terms of any insurance
settlement, such approval not to be unreasonably withheld or delayed, and to
receive at Closing the condemnation or insurance proceeds (or an assignment of
the right to such proceeds) (less any amounts applied against costs incurred or
income lost by Seller as a result of such occurrence) and Seller shall, at
Closing, execute and deliver to Purchaser all customary proofs of loss,
assignments of claims and other similar items. If either Seller or Purchaser
elects to terminate this Agreement pursuant to the provisions of this Section 5
and Purchaser is not in default under this Agreement, Seller shall promptly
notify the Escrowee to return the Earnest Money and, thereafter, the Earnest
Money shall be returned to Purchaser by the Escrowee, in which event this
Agreement shall, without further action of the parties, become null and void and
neither party shall have any further rights or obligations under this Agreement;
provided, however, that the foregoing shall not limit Seller's recourse against
Purchaser under Sections 6 and 11(G) below and under the "Confidentiality
Agreement" (as hereinafter defined).

     6.   BROKERAGE
          ---------

          Seller has agreed, pursuant to a separate written agreement with Penn
Square Properties, Inc. ("Penn Square"), to pay upon Closing (but not otherwise)
a brokerage commission to Penn Square for services rendered in connection with
the sale and purchase of the Property.  Seller shall indemnify and hold
Purchaser harmless from and against any and all claims of Penn Square related to
Seller's agreement to pay Penn Square a commission in connection with the
purchase and sale of the Property, including, without limitation, reasonable
attorneys' fees and expenses incurred by Purchaser in connection with such
claim.  Seller and Purchaser shall each indemnify and hold the other harmless
from and against any and all claims of all brokers and finders (other than a
claim by Penn Square against Seller of the type described in the preceding
sentence, which claim Seller shall be obligated to indemnify Purchaser against
in accordance with the preceding sentence) claiming by, through or under the
indemnifying party and in any way related to the sale and purchase of the
Property, this Agreement or otherwise, including, without limitation, reasonable
attorneys' fees and expenses incurred by the indemnified party in connection
with such claim.  The provisions of this Section 6 shall survive the Closing or
other termination of this Agreement.

     7.   DEFAULT AND REMEDIES
          --------------------

          A.   Notwithstanding anything to the contrary contained in this
Agreement, if (i) Seller fails to perform in accordance with the terms of this
Agreement, (ii) Purchaser is not otherwise in default hereunder, and (iii) the
Closing does not occur, then, as Purchaser's sole



                                       11

 
and exclusive remedy hereunder and at Purchaser's option, either (x) the Earnest
Money shall be returned to Purchaser, in which event this Agreement shall be
null and void, and neither party shall have any rights or obligations under this
Agreement, or (y) upon notice to Seller not less than ten (10) days after
Purchaser becomes aware of such failure, and provided an action is filed within
thirty (30) days thereafter, Purchaser may seek specific performance of this
Agreement, but not damages. Purchaser's failure to seek specific performance as
aforesaid shall constitute its election to proceed under clause (x) above.

          B. If Purchaser fails to perform in accordance with the terms of this
Agreement, the Earnest Money may be retained by Seller as liquidated and agreed
upon damages and as Seller's sole and exclusive remedy with respect thereto;
provided, however, that the foregoing shall not limit Seller's recourse against
Purchaser under Section 6 above and Section 11(G) below and under the
Confidentiality Agreement. If Purchaser is required to but does not deposit with
the Escrowee the Additional Earnest Money as provided for in Section 2(A)(i)
above, the sum of $200,000.00 shall nonetheless be recoverable by Seller from
Purchaser as Earnest Money in accordance with the preceding sentence. Purchaser
and Seller acknowledge and agree that (1) the Earnest Money is a reasonable
estimate of and bears a reasonable relationship to the damages that would be
suffered and costs incurred by Seller as a result of having withdrawn the
Property from sale and the failure of Closing to occur due to a default of
Purchaser under this Agreement; (2) the actual damages suffered and costs
incurred by Seller as a result of such withdrawal and failure to close due to a
default of Purchaser under this Agreement would be extremely difficult and
impractical to determine; (3) Purchaser seeks to limit its liability under this
Agreement to the amount of the Earnest Money in the event this Agreement is
terminated and the transaction contemplated by this Agreement does not close due
to a default of Purchaser under this Agreement; and (4) the Earnest Money shall
be and constitute valid liquidated damages.


          C. After Closing, Seller and Purchaser shall, subject to the terms and
conditions of this Agreement, have such rights and remedies as are available at
law or in equity, except that neither Seller nor Purchaser shall be entitled to
recover from the other consequential or special damages.

     8.   CONDITION PRECEDENT - REVIEW PERIOD

          A. Subject to Section 11(G) below and the provisions of that certain
letter agreement (the "Confidentiality Agreement") dated October 25, 1995 by and
between Penn Square and Purchaser, Purchaser shall have forty-five (45) days
after the date of this Agreement within which to inspect the Property and review
the items described in Section 8(B) below (the "Review Period"). Purchaser
and/or its employees shall visit the Property and commence Purchaser's "due
diligence" review of the Property within five (5) days after the commencement of
the Review Period, such visit to be confirmed by Seller's on-site property
manager. In the event that such visit does not occur within such five (5) day
period, Seller shall have the option, exercisable by written notice to Purchaser
prior to the end of the Review Period, to terminate this Agreement, and,
provided that Purchaser is not in default under the Confidentiality Agreement
and/or this Agreement (it being acknowledged by Seller that the failure of
Purchaser and/or its employees to visit the Property within five (5) days after
commencement of the Review Period shall not be deemed a default of Purchaser
hereunder), the Earnest Money shall be returned to Purchaser, at which time this
Agreement shall be null and void and neither party shall have any further rights
or obligations under this Agreement,

                                      12

 
provided, however, that the foregoing shall not limit Seller's recourse against
Purchaser under Section 6 above and Section 11(G) below and under the
Confidentiality Agreement. If Purchaser determines that the Property is
unsuitable for its purposes and notifies Seller of such decision within the
Review Period (such notice to contain Purchaser's certification that it has
elected not to purchase the Property for a reason or reasons relating to the
Property) and Purchaser is not in default under this Agreement and/or the
Confidentiality Agreement, the Earnest Money shall be returned to Purchaser, at
which time this Agreement shall be null and void and neither party shall have
any further rights or obligations under this Agreement, provided, however, that
the foregoing shall not limit Seller's recourse against Purchaser under Section
6 above and Section 11(G) below and under the Confidentiality Agreement.
Purchaser's failure to object within the Review Period shall be deemed a waiver
by Purchaser of the condition contained in this Section 8(A).

          B.   Seller shall, within ten (10) days after the date of this
Agreement, make available to Purchaser at the Property the following, to the
extent in Seller's possession:

               (i)     Copies of each of the Leases;

               (ii)    Copies of the most recent real estate tax statements with
                       respect to the Property;

               (iii)   Copies of the most recent sewer and water bills with
                       respect to the Property;

               (iv)    Copies of the Service Contracts;

               (v)     Copies of bills for fuel used to operate the heating and
                       air conditioning systems controlled by Seller at the
                       Property covering the period January 1, 1995 through the
                       last billing period ending prior to the date of this
                       Agreement, if any;

               (vi)    Copies of bills for electricity used to operate the
                       portion of the Property controlled by Seller covering the
                       period January 1, 1995 through the last billing period
                       ending prior to the date of this Agreement, if any;

               (vii)   Copies of correspondence between tenants and Seller (as
                       landlord), (except for any of such items that contain
                       privileged information);

               (viii)  Copies of 1995 billings to tenants for estimated
                       Operating Expense Reimbursements;

               (ix)    A rent roll for the Property dated not earlier than ten
                       (10) days prior to the date of this Agreement, setting
                       forth all tenants occupying space at the Property as of
                       such date, the space occupied by each tenant, the monthly
                       base rent and additional rent payable pursuant to each
                       tenant's Lease, and the approximate square footage
                       demised under the particular Lease;

                                      13

 
               (x)     Copies of drafts of leases that are unsigned and under
                       negotiation;

               (xi)    An accounts receivable aging report dated not earlier
                       than ten (10) days prior to the date of this Agreement;

               (xii)   Copies of any documentation filed with governmental
                       authorities in connection with the real estate tax
                       appeals discussed in Section 4(C)(iv) above;

               (xiii)  To the extent same are located at the Property, copies of
                       plans for the buildings located on the Property, if any;
                       and

               (xiv)   To the extent same are located at the Property, copies of
                       any licenses or permits issued to Seller in connection
                       with the ownership and operation of the Property.

     9.   ESTOPPEL CERTIFICATES

          A. In the event that neither Seller nor Purchaser elect to terminate
this Agreement pursuant to Section 8(A) above, Seller shall, within ten (10)
days after the expiration of the Review Period, send estoppel certificates
(individually, an "Estoppel Certificate" and collectively, the "Estoppel
Certificates") to each tenant occupying space at the Property as of the last day
of the Review Period. The Estoppel Certificates shall be in the form of Exhibit
E attached hereto (the "Form Tenant Estoppel Certificate").

          B. It shall be a condition precedent to Purchaser's obligation to
purchase the Property pursuant to this Agreement that Seller provide to
Purchaser, at Closing, Estoppel Certificates executed by tenants occupying not
less than seventy percent (70%) of the net rentable square footage of space
occupied by tenants at the Property as of the date of this Agreement (the
"Required Tenants"). The Estoppel Certificates executed by tenants shall be in
substantially the form of the Form Tenant Estoppel Certificate, except that an
Estoppel Certificate executed by a tenant shall be deemed an acceptable Estoppel
Certificate for purposes of this Section 9 as long as it contains the
information set forth in items 1 through 7 on the Form Tenant Estoppel
Certificate. Furthermore, an Estoppel Certificate shall be deemed an acceptable
Estoppel Certificate for purposes of this Section 9 if it contains the
qualification by the tenant of any statement as being to the best of its
knowledge or as being subject to any similar qualification (the aforesaid
acceptable Estoppel Certificates to be delivered are collectively referred to as
the "Required Estoppel Certificates").

          C. In the event that Seller is unable to provide to Purchaser the
Required Estoppel Certificates at Closing, Purchaser may either: (x) elect not
to purchase the Property, in which event this Agreement shall be null and void,
the Escrowee shall promptly return the Earnest Money to Purchaser and thereafter
neither Seller nor Purchaser shall have any further rights or obligations under
this Agreement, provided, however, that the foregoing shall not limit Seller's
recourse against Purchaser under Section 6 above and Section 11(G) below and
under the Confidentiality Agreement; or (y) elect to purchase the Property
notwithstanding Seller's

                                      14

 
inability to provide the Required Estoppel Certificates, in which event Seller
shall not be obligated to provide any additional Estoppel Certificates to
Purchaser after Closing.

          D. If any Estoppel Certificates contain statements or allegations that
a default or potential default exists on the part of Seller under the Lease in
question and (i) the existence or the substance of such allegations or
statements were contained in the documents and materials referred to in Section
8(B) above or any other "Disclosures" (as defined in Section 11(H) below) prior
to the end of the Review Period, or (ii) prior to the end of the Review Period
Purchaser otherwise obtained actual knowledge of facts revealing the substance
of such statements or allegations, or (iii) Seller otherwise disclosed in
writing the existence or the substance of such allegations or statements prior
to the end of the Review Period, then such Estoppel Certificates shall be deemed
acceptable for purposes of this Section 9, notwithstanding the existence of such
allegations or statements.

     10.  SELLER'S REPRESENTATIONS AND WARRANTIES

          A.   Seller represents and warrants to Purchaser the following:

               (i)    As of the date of this Agreement, to the "Actual Knowledge
                      of Seller" (as hereinafter defined), except as set forth
                      on Exhibit I attached hereto, Seller has received no
                      written notice from any governmental authority of any
                      material violation of any state or federal law, rule or
                      regulation concerning the Property or any part thereof
                      which has not been cured prior to the date of this
                      Agreement.

               (ii)   To the Actual Knowledge of Seller, the list attached
                      hereto as Exhibit D lists all of the maintenance, service,
                      advertising and other like contracts and agreements with
                      respect to the ownership and/or operation of the Property
                      (the "Service Contracts"), the vendor under each Service
                      Contract and the date of each Service Contract.

               (iii)  Except for litigation adequately covered by insurance and
                      except as set forth on Exhibit J attached hereto, as of
                      the date of this Agreement, Seller has received no written
                      notice of any pending litigation with respect to the
                      Property which would affect the Property after Closing.

          B. When used in this Agreement, the term "Actual Knowledge of Seller"
shall mean and be limited to the actual (and not constructive) current knowledge
of (i) Alissa Schneider, Assistant Vice President-Asset Management of Equity
Office Holdings, L.L.C., a Delaware limited liability company.

          C. The representations and warranties set forth in this Section 10
shall survive the Closing and the delivery of the Deed for a period of four (4)
months from the Closing Date.

                                      15

 
          D. Seller does not represent and warrant that any particular Service
Contract will be in force or effect as of the Closing or that tenants under
Leases or the parties to the Service Contracts will not be in default under
their respective Leases or Service Contracts, and neither the existence of any
default by any tenant under its Lease nor the default of any party under any
Service Contract shall affect the obligations of Purchaser hereunder; provided,
however, the foregoing shall not affect the conditions contained in Section 9
above.

          E. As and to the extent that Seller and Purchaser or its
representatives review copies of the documents and materials referred to in
Section 8(B) above and any other Disclosures prior to the end of the Review
Period and such documents or materials contain information inconsistent with or
different from the representations and warranties set forth in Section 10(A)
above, or prior to the end of the Review Period Purchaser otherwise obtains
actual knowledge of facts or Seller otherwise discloses in writing to Purchaser
facts that are inconsistent with or different from the representations and
warranties made in Section 10(A), then as of the end of the Review Period such
representations and warranties shall be deemed modified to conform them to the
information set forth in such documents and materials or to such other facts.

          F. As and to the extent that (i) Purchaser obtains actual knowledge of
facts, or (ii) any Estoppel Certificates or other documents with respect to
Leases and/or matters addressed by Section 10(A) are received by Purchaser or
received by Seller and delivered to Purchaser prior to the Closing, and the
Closing occurs, then the representations and warranties in Section 10(A) shall
be deemed to be modified and/or superseded by such facts, certificates and/or
other documents; provided, however, the foregoing shall not affect the
conditions contained in Section 9 above.

     11.  MISCELLANEOUS

          A. All understandings and agreements heretofore had between Seller and
Purchaser with respect to the Property are merged in this Agreement, which alone
fully and completely expresses the agreement of the parties. Purchaser
acknowledges that it has inspected or will inspect the Property and that it
accepts same in its "as is" condition subject to use, ordinary wear and tear and
natural deterioration. Purchaser further acknowledges that, except as expressly
provided in this Agreement, neither Seller nor any agent or representative of
Seller has made, and Seller is not liable for or bound in any manner by, any
express or implied warranties, guaranties, promises, statements, inducements,
representations or information pertaining to the Property.

          B. Neither this Agreement nor any interest hereunder shall be assigned
or transferred by Purchaser without the written consent of Seller, which consent
may be withheld in the sole and absolute discretion of Seller except for an
assignment of the type described in the next sentence. Purchaser shall be
permitted to assign its rights and obligations under this Agreement to an entity
(a "Permitted Assignee") of which Purchaser or an entity affiliated with and
under common control with Purchaser is the sole general partner and, upon such
an assignment such Permitted Assignee shall execute and deliver an agreement to
Seller in which such Permitted Assignee assumes all of the obligations of
Purchaser under this Agreement. Upon an assignment of this Agreement to a
Permitted Assignee: (1) Purchaser shall not be relieved of any subsequently
accruing liability under this Agreement, and (2) as used in this Agreement, the
term "Purchaser" shall be deemed to include such Permitted Assignee. Seller

                                      16

 
may assign or otherwise transfer its interest under this Agreement. As used in
this Agreement, the term "Seller" shall be deemed to include any assignee or
other transferee of any Seller. Upon any such transfer by a Seller, such Seller
shall be relieved of any subsequently accruing liability under this Agreement.
Subject to the foregoing, this Agreement shall inure to the benefit of and shall
be binding upon Seller and Purchaser and their respective successors and
assigns.

          C.   This Agreement shall not be modified or amended except in a
written document signed by Seller and Purchaser.

          D.   Time is of the essence of this Agreement.

          E.   This Agreement shall be governed and interpreted in accordance
with the laws of the Commonwealth of Pennsylvania.

          F.   All notices, requests, demands or other communications required
or permitted under this Agreement shall be in writing and delivered personally,
by certified mail, return receipt requested, postage prepaid, by overnight
courier (such as Federal Express), or by facsimile transmission, addressed as
follows:

               1.   If to Seller:

                    c/o Equity Office Holdings, L.L.C.
                    Two North Riverside Plaza
                    Suite 2244
                    Chicago, Illinois  60606
                    Telephone:  (312) 466-3595
                    Facsimile:  (312) 559-5051

                    Attention:  Alissa Schneider

                    With a copy to:

                    Rosenberg & Liebentritt, P.C.
                    Suite 1515
                    Two North Riverside Plaza
                    Chicago, Illinois  60606
                    Telephone:  (312) 466-3483
                    Facsimile:  (312) 454-0335

                    Attention:  Steven E. Ehrlich, Esq.

                      
                                      17

 
               2.   If to Purchaser:

                    BGK Properties, Inc.
                    330 Garfield Street, Suite 200
                    Santa Fe, Mexico  87501
                    Telephone:  (505) 982-2184
                    Facsimile:  (505) 982-2515

                    Attention:  Mr. Ed Gilbert

                    With a copy to:

                    BGK Properties, Inc.
                    330 Garfield Street, Suite 200
                    Santa Fe, New Mexico  87501
                    Telephone:  (505) 982-2184
                    Facsimile:  (505) 982-2515

                    Attention:  Sam Konigsberg, Esq.

All notices given in accordance with the terms hereof shall be deemed received
forty-eight (48) hours after posting, or when delivered personally or otherwise
received.  Either party hereto may change the address for receiving notices,
requests, demands or other communication by notice sent in accordance with the
terms of this Section 11(F).

          G.   Purchaser's right of inspection pursuant to Section 8(A) above
shall be subject to the rights of tenants under the Leases and other occupants
and users of the Property.  No inspection shall be undertaken without reasonable
prior notice to Seller.  Seller shall have the right to be present at any or all
inspections.  Neither Purchaser nor its agents or representatives shall contact
any tenants without the prior consent of Seller.  No inspection shall involve
the taking of samples or other physically invasive procedures without the prior
consent of Seller.  Notwithstanding anything to the contrary contained in this
Agreement, Purchaser shall indemnify and hold Seller and its employees and
agents, and each of them, harmless from and against any and all losses, claims,
damages and liabilities (including, without limitation, attorneys' fees incurred
in connection therewith) arising out of or resulting from Purchaser's exercise
of its rights under this Agreement, including, without limitation, its right of
inspection as provided for in Section 8(A) above.  The provisions of this
Section 11(G) shall survive the Closing or other termination of this Agreement.

          H.   ACKNOWLEDGING THE PRIOR USE OF THE PROPERTY AND PURCHASER'S
OPPORTUNITY TO INSPECT THE PROPERTY, PURCHASER AGREES TO TAKE THE PROPERTY "AS
IS" WITH ALL FAULTS AND CONDITIONS THEREON.  ANY INFORMATION, REPORTS,
STATEMENTS, DOCUMENTS OR RECORDS (COLLECTIVELY, THE "DISCLOSURES") PROVIDED OR
MADE TO PURCHASER OR ITS CONSTITUENTS BY SELLER, ITS AGENTS OR EMPLOYEES
CONCERNING THE CONDITION OF THE PROPERTY SHALL NOT BE REPRESENTATIONS OR
WARRANTIES.  PURCHASER SHALL NOT RELY ON SUCH DISCLOSURES, BUT RATHER, PURCHASER
SHALL RELY ONLY ON ITS OWN INSPECTION OF THE PROPERTY.  PURCHASER ACKNOWLEDGES
AND AGREES THAT, EXCEPT AS EXPRESSLY PROVIDED IN THIS AGREEMENT, SELLER HAS NOT
MADE, DOES NOT MAKE AND SPECIFICALLY DISCLAIMS ANY REPRESENTATIONS, WARRANTIES,
PROMISES, 

                                       
                                      18

 
COVENANTS, AGREEMENTS OR GUARANTIES OF ANY KIND OR CHARACTER WHATSOEVER, WHETHER
EXPRESS OR IMPLIED, ORAL OR WRITTEN, PAST, PRESENT OR FUTURE, OF, AS TO,
CONCERNING OR WITH RESPECT TO (A) THE NATURE, QUALITY OR CONDITION OF THE
PROPERTY, INCLUDING, WITHOUT LIMITATION, THE WATER, SOIL AND GEOLOGY, (B) THE
INCOME HERETOFORE DERIVED OR TO BE DERIVED FROM THE PROPERTY, (C) THE
SUITABILITY OF THE PROPERTY FOR ANY AND ALL ACTIVITIES AND USES WHICH PURCHASER
MAY CONDUCT THEREON, (D) THE COMPLIANCE OF OR BY THE PROPERTY OR ITS OPERATION
WITH ANY LAWS, RULES, ORDINANCES OR REGULATIONS OF ANY APPLICABLE GOVERNMENTAL
AUTHORITY OR BODY, (E) THE HABITABILITY, MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE OF THE PROPERTY, OR (F) ANY OTHER MATTER WITH RESPECT TO THE
PROPERTY, AND SPECIFICALLY DISCLAIMS ANY REPRESENTATIONS REGARDING TERMITES OR
WASTES, AS DEFINED BY THE U.S. ENVIRONMENTAL PROTECTION AGENCY REGULATIONS AT 40
C.F.R., OR ANY HAZARDOUS SUBSTANCE, AS DEFINED BY THE COMPREHENSIVE
ENVIRONMENTAL RESPONSE COMPENSATION AND LIABILITY ACT OF 1980 ("CERCLA"), AS
AMENDED, AND REGULATIONS PROMULGATED THEREUNDER.

               PURCHASER, ITS SUCCESSORS AND ASSIGNS, HEREBY WAIVE, RELEASE AND
AGREE NOT TO MAKE ANY CLAIM OR BRING ANY COST RECOVERY ACTION OR CLAIM FOR
CONTRIBUTION OR OTHER ACTION OR CLAIM AGAINST SELLER OR ITS AFFILIATES,
DIRECTORS, OFFICERS, EMPLOYEES, AGENTS, ATTORNEYS, OR ASSIGNS (COLLECTIVELY,
"SELLER AND ITS AFFILIATES") BASED ON (A) ANY FEDERAL, STATE, OR LOCAL
ENVIRONMENTAL OR HEALTH AND SAFETY LAW OR REGULATION, INCLUDING CERCLA OR ANY
STATE EQUIVALENT, OR ANY SIMILAR LAW NOW EXISTING OR HEREAFTER ENACTED, (B) ANY
DISCHARGE, DISPOSAL, RELEASE, OR ESCAPE OF ANY CHEMICAL, OR ANY MATERIAL
WHATSOEVER, ON, AT, TO, OR FROM THE PROPERTY; OR (C) ANY ENVIRONMENTAL
CONDITIONS WHATSOEVER ON, UNDER, OR IN THE VICINITY OF THE PROPERTY.

          I.   In any lawsuit or other proceeding initiated by Purchaser under
or with respect to this Agreement, Purchaser waives any right it may have to
trial by jury.  In addition, Purchaser waives any right to seek rescission of
the transaction provided for in this Agreement.

          J.   Purchaser acknowledges that all information with respect to the
Property furnished or to be furnished to Purchaser is, has been and will be so
furnished on the condition that Purchaser maintain the confidentiality thereof.
Accordingly, Purchaser shall, and shall cause its directors, officers and other
personnel and representatives to, hold in strict confidence, and not disclose to
any other party without the prior written consent of Seller and unless the
Closing occurs: (i) any of the information with respect to the Property
delivered to Purchaser by Seller or any of its agents, representatives or
employees, or (ii) the existence of this Agreement or any term or condition
thereof, or (iii) the results of any inspections or studies undertaken in
connection herewith.  In addition, neither Purchaser nor Purchaser's directors,
officers and other personnel and representatives shall solicit offers to
purchase the Property to any other party without the prior written consent of
Seller and unless the Closing occurs.  Notwithstanding the above, Purchaser may
disclose such information to individuals or entities necessary for Purchaser to
consummate the transaction contemplated herein (such as lenders, engineers,
prospective management companies, environmental consultants, accountants and tax
advisors) and as required by law. Purchaser shall require that any parties to
whom the existence of this Agreement or any information with respect to the
Property is disclosed execute a confidentiality agreement wherein the party
agrees not to disclose the existence of this Agreement or information with
respect to the 

               
                                      19

 
Property to anyone. In the event the Closing does not occur and this Agreement
is terminated, Purchaser shall, upon written request by Seller, promptly return
to Seller all copies of all such information without retaining any copy thereof
or extract therefrom.

          K.   If for any reason Purchaser does not consummate the Closing, then
Purchaser shall, upon Seller's request, assign and transfer to Seller all of its
right, title and interest in and to any and all studies, reports, surveys and
other information, data and/or documents relating to the Property or any part
thereof prepared by or at the request of Purchaser, its employees and agents,
and shall deliver to Seller copies of all of the foregoing.

          L.   Seller hereby covenants and agrees with Purchaser that:

               1.   From and after the date hereof through the Closing, Seller
          shall deliver for Purchaser's review (a "New Lease Notice") a copy of
          any proposed new Lease, or any modification, amendment, restatement or
          renewal of any existing Lease (individually, a "New Lease" and
          collectively, "New Leases"). During the period between the Review
          Period and Closing, Purchaser shall have the right to approve or
          disapprove of any New Lease by responding in writing to Seller's New
          Lease Notice within five (5) days after Purchaser's receipt of the New
          Lease Notice. If Purchaser fails to approve or disapprove of such New
          Lease within such five (5) day period, Purchaser shall be deemed to
          have conclusively approved of such New Lease.

               2.   All tenant improvement costs and/or allowances and leasing
          commissions relating to (a) New Leases entered into by Seller during
          the period between the date of this Agreement and the expiration of
          the Review Period, and (b) New Leases entered into by Seller after the
          Review Period which Purchaser approves (or is deemed to approve) in
          accordance with Section 11(L)(1) above, shall be prorated in
          accordance with Section 4(c)(i)(d) above.

          M.   Purchaser shall be obligated to assume pursuant to the Service
Contract Assignment any Service Contract that would require Seller to pay a fee,
penalty or damages if terminated at or prior to Closing (collectively, the
"Required Service Contracts").  In the event that there are Service Contracts
that are not Required Service Contracts (individually, a "Terminable Service
Contract", and collectively, the "Terminable Service Contracts"), Purchaser
shall notify Seller in writing on or before the expiration of the Review Period
as to which Terminable Service Contracts Purchaser shall assume at Closing
pursuant to the Service Contract Assignment and, in the event that Purchaser
does not notify Seller as aforesaid prior to the expiration of the Review
Period, Purchaser shall be obligated to assume all Terminable Service Contracts
at Closing.

          N.   Seller and Purchaser hereby designate Escrowee to act as and
perform the duties and obligations of the "reporting person" with respect to the
transaction contemplated by this Agreement for purposes of 26 C.F.R. Section
1.6045-4(e)(5) relating to the requirements for information reporting on real
estate transaction closed on or after January 1, 1991.  In this regard, Seller
and Purchaser each agree to execute at Closing, and to cause the Escrowee to
execute at Closing, a Designation Agreement, designating Escrowee as the
reporting person with respect to the transaction contemplated by this Agreement.

          
                                      20

 
          O.   This Agreement may be executed in two or more counterparts, each
of which shall be deemed to be an original and all of which taken together shall
constitute one and the same instrument.

          P.   Seller and Purchaser acknowledge and agree that neither this
Agreement nor a memorandum thereof shall be recorded against the Property.

          Q.   Purchaser acknowledges and agrees that any recovery against
Seller that Purchaser may be entitled to as a result of any claim, demand or
cause of action that Purchaser may have against Seller with respect to this
Agreement and the transactions contemplated herein shall only be recoverable
against Seller to the extent of Seller's interest in the Property and the amount
of the proceeds received by Seller from the sale of the Property to Purchaser.

          R.   Seller is a party to that certain Easement Agreement (the "Sewer
Easement Agreement") dated December 19, 1995 by and between Wolf Property, Inc.,
a Pennsylvania corporation ("Wolf"), and Seller, a copy of which is attached
hereto as Exhibit K. As more particularly described in the Sewer Easement
Agreement, Seller has, among other things, agreed to (i) grant certain easements
in favor of land owned by Wolf that is adjacent to the Real Property for
emergency access and the placement of sanitary sewer lines, and (ii) execute a
deed of dedication in favor of Whitpain Township.  Prior to the date of this
Agreement, Seller authorized Wolf to record the Sewer Easement Agreement with
the Office of the Montgomery County, Pennsylvania Recorder (the "Recorder"); as
of the date of this Agreement, Wolf has not yet provided Seller with a copy of
the recorded Sewer Easement Agreement.  If the recording information for the
Sewer Easement Agreement is not provided in the Title Commitment and Seller
receives such recording information from Wolf after the date of this Agreement
and prior to Closing, Seller shall provide such recording information to
Purchaser after Seller's receipt of same.

               In connection with the Sewer Easement Agreement, Rosenberg &
Liebentritt, P.C. ("R&L"), in its capacity as counsel for Seller, Lesser &
Kaplin, in its capacity as counsel for Wolf, and Security Abstract of PA, Inc.
("Security"), as escrowee, have entered into a letter agreement (the "Sewer
Escrow Agreement") with respect to, among other matters, the deposit, delivery
and recordation of the deeds of dedication described in the Sewer Easement
Agreement.  A copy of the Sewer Escrow Agreement is attached hereto as Exhibit
L.  As of the date of this Agreement, Security is holding in escrow (the "Sewer
Escrow"), pursuant to the Sewer Escrow Agreement, the deed of dedication in
favor of Whitpain Township that is referenced in Exhibit G to the Sewer Easement
Agreement, executed on behalf of Seller (the "Seller Deed of Dedication").  In
the event that the Seller Deed of Dedication is not recorded with the Recorder
prior to the Closing, Purchaser shall execute a deed of dedication (the
"Substitute Deed of Dedication") at Closing in favor of Whitpain Township
identical to the Seller Deed of Dedication (except that the Substitute Deed of
Dedication shall name Purchaser as "grantor" thereunder rather than Seller).  At
Closing, Purchaser shall assume all of Seller's obligations under the Sewer
Easement Agreement and the Sewer Escrow Agreement including, without limitation,
the obligation to execute and deliver the deed of dedication referenced in
Exhibit G to the Sewer Easement Agreement, if required by Wolf and/or Whitpain
Township, by executing the Assignment and Assumption of Title Documents in
accordance with Section 4(B)(ii)(f) above.  In addition, at Closing, Purchaser,
Seller and R&L shall execute a letter (the "Escrow Assumption Letter") addressed
to Security and Wolf, confirming that Purchaser has 

               
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assumed all of Seller's obligations under the Sewer Escrow Agreement and the
Sewer Easement Agreement. In the event that the Seller Deed of Dedication has
not been recorded with the Recorder by the Closing Date, the Escrow Assumption
Letter shall deposit the Substitute Deed of Dedication into the Sewer Escrow in
substitution for the Seller Deed of Dedication.

          S.   In the event of a conflict between the terms and provisions of
the Confidentiality Agreement and this Agreement, the terms and provisions of
this Agreement shall control.

          T.   Except as specifically provided for herein, the representations,
warranties, covenants and agreements of Seller set forth in this Agreement shall
not survive the Closing.

              [THE REMAINDER OF THIS PAGE IS INTENTIONALLY BLANK]

                                      22

 
     IN WITNESS WHEREOF, Seller and Purchaser have executed and delivered this
Agreement as of the date first above written.

                    SELLER:

                    SENTRY WEST JOINT VENTURE, an Illinois joint venture
                    partnership

                    By:  Blue Bell Associates, an Illinois joint venture, as
                         managing general partner

                         By:  First Capital Income Properties, Ltd. - Series XI,
                              an Illinois limited partnership, a general partner
                              of Blue Bell Associates

                              By:   First Capital Financial Corporation, a
                                    Florida corporation, as the general partner
                                    of First Capital Income Properties, Ltd. -
                                    Series XI

                                    By: /s/ Norman Field
                                       -----------------------------------------
                                    Name:   Norman Field
                                         ---------------------------------------
                                    Its:    Vice President
                                        ----------------------------------------

                         By:  First Capital Income and Growth Fund - Series XII,
                              an Illinois limited partnership, a general partner
                              of Blue Bell Associates

                              By:   First Capital Financial Corporation, a
                                    Florida corporation, as the general partner
                                    of First Capital Income and Growth Fund -
                                    Series XII

                                    By: /s/ Norman Field
                                       -----------------------------------------
                                    Name:   Norman Field
                                         ---------------------------------------
                                    Its:    Vice President
                                        ----------------------------------------


                    PURCHASER:

                    BGK PROPERTIES, INC., a Delaware corporation

                    By:  /s/ Edward M. Gilbert
                       ---------------------------------------------------------
                    Name:    Edward M. Gilbert
                         -------------------------------------------------------
                    Its:     President
                        --------------------------------------------------------

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