Exhibit 5


                   SIDLEY AUSTIN BROWN & WOOD LLP

 BEIJING                  787 SEVENTH AVENUE                     LOS ANGELES
 -------               NEW YORK, NEW YORK 10019                    -------
 BRUSSELS               TELEPHONE 212 839 5300                     NEW YORK
 -------                FACSIMILE 212 839 5599                     -------
 CHICAGO                    www.sidley.com                      SAN FRANCISCO
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  DALLAS                     FOUNDED 1866                          SHANGHAI
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  GENEVA                                                          SINGAPORE
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HONG KONG                                                           TOKYO
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  LONDON                                                       WASHINGTON, D.C.





                                       June 27, 2005


Reckson Operating Partnership, L.P.
Reckson Associates Realty Corp.
225 Broadhollow Road
Melville, New York 11747

Ladies and Gentlemen:

     This opinion is furnished in connection with the Registration Statement
on Form S-3 (File No. 333-115997) filed with the Securities and Exchange
Commission (the "Commission") under the Securities Act of 1933, as amended
(the "Securities Act"), relating to the public offering of up to $287,500,000
aggregate principal amount of 4.00% Exchangeable Senior Debentures due 2025
(the "Debentures") by Reckson Operating Partnership, L.P., a Delaware limited
partnership (the "Operating Partnership"), on terms set forth in a prospectus
supplement dated June 21, 2005 to the prospectus dated July 13, 2004
(collectively, the "Prospectus"). The Debentures will be fully and
unconditionally guaranteed (the "Guarantee") as to the payment of principal
thereof and interest thereon by Reckson Associates Realty Corp., a Maryland
corporation and the general partner of the Operating Partnership (the
"Company"). The Debentures will be issued pursuant to an indenture dated as of
March 26, 1999 among the Operating Partnership, as issuer, the Company, as
guarantor, and The Bank of New York, as trustee, including the Officers'
Certificate establishing the terms of the Debentures (collectively, the
"Indenture").

     In arriving at the opinions expressed below, we have examined such
documents and records as we deemed appropriate, including the following: the
Certificate of Limited Partnership and the Amended and Restated Agreement of
Limited Partnership, as amended, of the Operating Partnership, the Charter and
the Amended and Restated Bylaws, as amended, of the Company; records of
corporate proceedings of the Company; the Registration Statement; the
Indenture; the form of global note evidencing the Debentures; the Prospectus;
and such other certificates, receipts, records and documents as we considered
necessary for the purposes of this opinion.

     Based upon the foregoing, and subject to the limitations, qualifications
and exceptions set forth herein, we are of the opinion that:





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 PRACTICING IN AFFILIATION WITH OTHER SIDLEY AUSTIN BROWN & WOOD PARTNERSHIPS



     (i) The Debentures have been duly authorized by all necessary partnership
action of the Operating Partnership and, when the Debentures have been duly
executed, authenticated and delivered against consideration therefor as
contemplated in the Indenture and the Prospectus, the Debentures will
constitute valid and legally binding obligations of the Operating Partnership
and registered holders of the Debentures will be entitled to the benefits of
the Indenture; provided, however, that the foregoing opinion is subject, as to
enforcement against the Operating Partnership, to bankruptcy, insolvency,
reorganization, moratorium or other similar laws relating to or affecting the
enforcement of creditors' rights generally and to general principles of equity
(regardless of whether enforcement is considered in a proceeding in equity or
at law).

     (ii) The Guarantee has been duly authorized by all necessary corporate
action of the Company and, when the Debentures are executed, authenticated,
issued and delivered as contemplated in the Indenture and the Prospectus, the
Guarantee will constitute a valid and legally binding obligation of the
Company; provided, however, that the foregoing opinion is subject, as to
enforcement against the Company, to bankruptcy, insolvency, reorganization,
moratorium or other similar laws relating to or affecting the enforcement of
creditors' rights generally and to general principles of equity (regardless of
whether enforcement is considered in a proceeding in equity or at law).

     (iii) The shares of common stock, par value $0.01 per share, of the
Company (the "Common Stock") that are issuable upon an exchange of the
Debentures under certain circumstances (the "Underlying Shares") have been
duly authorized and reserved for issuance by the Company. The Underlying
Shares, if and when issued and delivered by the Company upon an exchange in
accordance with the Debentures and the Indenture, will be validly issued,
fully paid and non-assessable shares of Common Stock.

     This letter is limited to matters arising under the federal laws of the
United States of America, the laws of the State of New York, the Delaware
Revised Uniform Limited Partnership Act and the Maryland General Corporation
Law and we express no opinion or other statement as to the laws of any other
jurisdiction or as to the municipal laws, or the laws, rules or regulations of
any local agencies, of or within the State of New York, the State of Delaware
or the State of Maryland.

     We hereby consent to the filing of this opinion as an exhibit to the
Current Report of the Company and the Operating Partnership on Form 8-K dated
June 27, 2005 and to the references to our firm in the Prospectus under the
caption "Legal Matters."

                                       Very truly yours,

                                       /s/ Sidley Austin Brown & Wood LLP



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