Exhibit 5.1


                               Goodwin Procter LLP
                               Counsellors at Law
                                 Exchange Place
                                Boston, MA 02109

                                                  February 11, 2002



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

Ladies and Gentlemen:

     This opinion is furnished in connection with the registration on Form S-3
(the "Registration Statement") pursuant to the Securities Act of 1933, as
amended (the "Securities Act"), of the issuance of up to 650,876 shares (the
"Shares") of common stock, par value $.01 per share ("Common Stock"), of Boston
Properties, Inc. (the "Company"). The Shares may be issued by the Company if and
to the extent that the common units of limited partnership (the "Common Units")
of Boston Properties Limited Partnership, a Delaware limited partnership (the
"Operating Partnership") issuable upon conversion of Series Z preferred units of
the Operating Partnership, are presented to the Operating Partnership for
redemption and the Company elects to issue such Shares in exchange for such
Common Units.

     In connection with rendering this opinion, we have examined the Amended and
Restated Certificate of Incorporation and Amended and Restated Bylaws of the
Company, each as amended to date; such records of the corporate proceedings of
the Company as we deemed material; and such other certificates, receipts,
records and documents as we considered necessary for the purposes of this
opinion. In our examination, we have assumed the genuineness of all signatures,
the legal capacity of natural persons, the authenticity of all documents
submitted to us as certified, photostatic or facsimile copies, the authenticity
of the originals of such copies and the authenticity of telephonic confirmations
of public officials and others. As to facts material to our opinion, we have
relied upon certificates or telephonic confirmations of public officials and
certificates, documents, statements and other information of the Company or
representatives or officers thereof.

     We are attorneys admitted to practice in The Commonwealth of Massachusetts.
We express no opinion concerning the laws of any jurisdictions other than the
laws of the United States of America, the laws of The Commonwealth of
Massachusetts, and the Delaware General Corporation Law (which includes
applicable provisions of the Delaware Constitution and reported judicial
decisions interpreting the Delaware General Corporation Law and the Delaware
Constitution).



Boston Properties, Inc.
February 11, 2002
Page 2

     Based upon the foregoing, we are of the opinion that when the Shares have
been issued in exchange for Common Units tendered to the Operating Partnership
for redemption as contemplated by the limited partnership agreement of the
Operating Partnership, such Shares will be validly issued, fully paid and
nonassessable.

     The foregoing assumes that all requisite steps were taken to comply with
the requirements of the Securities Act and applicable requirements of state laws
regulating the offer and sale of securities.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to us with respect to this opinion
under the heading "Legal Matters" in the Prospectus which is a part of such
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
Act.

                                                Very truly yours,


                                                /s/ Goodwin Procter LLP

                                                Goodwin Procter LLP