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                                                                     Exhibit 8.1


                               GOODWIN PROCTER LLP
                               COUNSELLORS AT LAW
                                 EXCHANGE PLACE
                           BOSTON, MASSACHUSETTS 02109


March 6, 2003

Boston Properties, Inc.
Boston Properties Limited Partnership
111 Huntington Avenue
Suite 300
Boston, MA 02199

Ladies and Gentlemen:

This opinion is furnished in connection with the offer to exchange up to
$925,000,000 aggregate principal amount of 6.25% Senior Notes due 2013 issued by
Boston Properties Limited Partnership (the "Operating Partnership") for all of
the $925,000,000 aggregate principal amount of the Operating Partnership's
outstanding 6.25% Senior Notes due 2013 pursuant to a registration statement
(the "Registration Statement") on Form S-4 filed by the Operating Partnership
with the Securities and Exchange Commission on or about the date hereof. This
opinion relates to the qualification of Boston Properties, Inc. (the "Company")
for federal income tax purposes as a real estate investment trust within the
meaning of Sections 856-860 of the Internal Revenue Code of 1986, as amended
(the "Code").

In rendering the following opinion, we have examined the Amended and Restated
Certificate of Incorporation and Bylaws of the Company, the Registration
Statement, the Amended and Restated Limited Partnership Agreement of Boston
Properties Limited Partnership, and such other records, certificates and
documents as we have deemed necessary or appropriate for purposes of rendering
the opinion set forth herein. We have reviewed the investment activities,
operations and governance of the Company and its subsidiaries. We have relied
upon representations of duly appointed officers of the Company and the Operating
Partnership (including without limitation, representations contained in a letter
dated as of this date (the "Officer's Certificate")), principally relating to
the Company's organization and operations. We assume that each such
representation is and will be true, correct and complete and that all
representations that speak in the future, or to the intention, or to the best of
the belief and knowledge of any person(s) or party(ies) are and will be true,
correct and complete as if made without such qualification. Nothing has come to
our attention which would cause us to believe that any of such representations
are untrue, incorrect or incomplete. We assume that the Company will be operated
in accordance with the applicable laws and the terms and conditions of
applicable documents. In addition, we have relied upon certain additional facts
and assumptions described below.

In rendering the opinion set forth herein, we have assumed (i) the genuineness
of all signatures on documents we have examined, (ii) the authenticity of all
documents submitted to us as




originals, (iii) the conformity to the original documents of all documents
submitted to us as copies, (iv) the conformity of final documents to all
documents submitted to us as drafts, (v) the authority and capacity of the
individual or individuals who executed any such documents on behalf of any
person, (vi) the accuracy and completeness of all records made available to us,
and (vii) the factual accuracy of all representations, warranties and other
statements made by all parties. In addition, we assume that all interests in the
Operating Partnership have been and will be issued in a transaction (or
transactions) that are not required to be registered under the Securities Act of
1933, as amended, and that no interest in the Operating Partnership offered for
sale outside the United States would have been required to be registered under
the Securities Act of 1933, as amended, if such interest had been offered for
sale within the United States. We have further assumed that during its short
1997 taxable year ending December 31, 1997 and subsequent taxable years, the
Company has operated and will operate in such a manner that has made and will
make the representations contained in the Officer's Certificate true for all
such years, and that the Company and its subsidiaries will not make any
amendments to its organizational documents after the date of this opinion that
would affect the Company's qualification as a real estate investment trust for
any taxable year. For purposes of our opinion, we have made no independent
investigation of the facts contained in the documents and assumptions set forth
above, the representations set forth in the Officer's Certificate, or the
Registration Statement. No facts have come to our attention, however, that would
cause us to question the accuracy and completeness of such facts or documents in
a material way.

The discussion and conclusion set forth below are based upon the Code, the
Income Tax Regulations and Procedure and Administration Regulations promulgated
thereunder and administrative and judicial interpretation thereof, in each case
as currently exist and all of which are subject to change, and the opinions
below are rendered as of the date hereof, and we disclaim any obligation to
advise you of any change in any of the foregoing sources of law or subsequent
developments in law or changes in facts or circumstances which might affect any
matters or opinions set forth herein. No assurance can therefore be given that
the federal income tax consequences described below will not be altered in the
future. Based on the documents and assumptions set forth above and the
representations set forth in the Officer's Certificate, and provided that the
Company continues to meet the applicable asset composition, source of income,
shareholder diversification, distribution, and other requirements of the Code
necessary for a corporation to qualify as a real estate investment trust, we are
of the opinion that:

       (1) Commencing with the Company's initial taxable year ended December 31,
1997, the Company has been organized in conformity with the requirements for
qualification as a "real estate investment trust" under the Code, and its method
of operation enables it to meet the requirements for qualification as a "real
estate investment trust" under the Code, provided that the Company continues to
meet the applicable asset composition, source of income, shareholder
diversification, distribution, record keeping and other requirements of the Code
necessary for a corporation to qualify as a real estate investment trust, and

       (2) The information in the Registration Statement under the caption
"United States Federal Income Tax Consequences" to the extent that it
constitutes matters of law or legal conclusions, have been reviewed by us and is
correct in all material respects, and our opinion set forth in such discussion
is confirmed.





We will not review on a continuing basis the Company's compliance with the
documents or assumptions set forth above, or the representations set forth in
the Officer's Certificate. Accordingly, no assurance can be given that the
actual results of the Company's operations for any given taxable year will
satisfy the requirements for qualification and taxation as a real estate
investment trust under the Code. The ability of the Company to continue to meet
the requirements for qualification and taxation as a real estate investment
trust will be dependent upon the Company's ability to continue to meet in each
year the applicable asset composition, source of income, shareholder
diversification, distribution, and other requirements of the Code necessary for
a corporation to qualify as a real estate investment trust.

The foregoing opinion is limited to the federal income tax matters addressed
herein, and no other opinion is rendered with respect to other federal tax
matters or to any issues arising out of the tax laws of any state or locality.
We express no opinion with respect to the transactions described herein other
than those expressly set forth herein. You should recognize that our opinion is
not binding on the Internal Revenue Service and that the Internal Revenue
Service may disagree with the opinion contained herein. Although we believe that
our opinion will be sustained if challenged, there is no guarantee that this
will be the case. Except as specifically discussed above, the opinion expressed
herein is based upon the laws that currently exist. Consequently, future changes
in the law may cause the federal income tax treatment of the transactions herein
to be materially and adversely different from that described above.

We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to our firm under the caption
"United States Federal Income Tax Consequences" in the Registration Statement.
In giving such consent, we do not thereby admit that we are in the category of
persons whose consent is required under Section 7 of the Securities Act of 1933,
as amended, or the rules and regulations of the Securities and Exchange
Commission thereunder.


                                         Very truly yours,

                                         /s/ GOODWIN PROCTER LLP
                                         -----------------------------------
                                         Goodwin Procter LLP