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                           PURCHASE AND SALE AGREEMENT

                                 BY AND BETWEEN

                             KEYSTONE PROPERTY TRUST
                                  (as "Buyer")

                                       AND

                       RECKSON OPERATING PARTNERSHIP, L.P.
                                       and
                        RECKSON CONSTRUCTION GROUP, INC.
                                 (as "Sellers")

                           DATED AS OF AUGUST 21, 2001


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         PURCHASE AND SALE AGREEMENT, dated as of August 21, 2001 (the
"Agreement") by and between Reckson Operating Partnership, L.P., a Delaware
limited partnership ("ROP"), and Reckson Construction Group, Inc., a New York
corporation ("RCG," and together with ROP, the "Sellers") and Keystone Property
Trust, a Maryland real estate investment trust (the "Buyer").

         WHEREAS, the Sellers desire to sell and transfer to Buyer 2,500,000
common shares of beneficial interest to be received by the Sellers (the "Common
Shares") upon conversion and/or exchange of the securities described on EXHIBIT
A hereto (the "Securities") and Buyer wishes to acquire the Common Shares on the
terms set forth in this Agreement; and

         WHEREAS, the conversion and/or exchange of the Securities into the
Common Shares shall occur immediately prior to the Closing (as defined below) of
the Common Shares on the Closing Date (as defined below).

         THEREFORE, the parties hereto agree as follows:

         1. SALE AND PURCHASE OF THE SECURITIES. Each Seller hereby agrees to
assign, sell, convey and transfer to Buyer on the Closing Date (as defined
below) all right, title and interest of such Seller in and to the respective
number of Common Shares to be received by such Seller upon conversion and/or
exchange of the Securities set forth opposite such Seller's name on EXHIBIT A
hereto and Buyer, in reliance on the representations and warranties set forth
herein, agrees to pay to such Seller the respective amount of the Purchase
Price (as defined herein) in respect of such sale as set forth opposite such
Seller's name on EXHIBIT A hereto. The Common Shares shall be free and clear
of all liens, pledges, claims, security interests, encumbrances, charges,
restrictions or limitations of any kind, whether arising by agreement,
operation of law or otherwise (collectively, "Liens"). On the Closing Date
and pursuant to instructions from American Stock Transfer & Trust Company,
each of the Sellers and Buyer shall instruct American Stock Transfer & Trust
Company to record the transfer to the Buyer of the uncertificated Common
Shares owned by the Sellers after conversion of the Securities.

         2. CLOSING. The closing of the purchase and sale of the Common
Shares (the "Closing") shall take place on August 27, 2001 and the Sellers
will assign, sell, convey and transfer to Buyer in accordance with Section 1
above all right, title and interest of Sellers in and to the Common Shares
for an aggregate purchase price of $35,700,000 (the "Purchase Price"). Buyer
shall pay to each Seller, in accordance with EXHIBIT A, such Seller's
respective amount of the Purchase Price in immediately available funds by
wire transfer on the Closing Date to an account designated by the respective
Seller in writing at least two business days prior to the Closing Date.

         3. REPRESENTATIONS AND WARRANTIES OF SELLERS. Each Seller hereby
represents and warrants to Buyer that each of the following statements is
true and correct as of the date hereof and will be true and correct as of the
Closing Date as if made on such date.

         (a) GOOD STANDING. Seller is duly organized, validly existing and in
good standing in the state of its organization, with full corporate or
partnership power, as applicable, and authority to carry on its business as
it is now operated and carried on by it.
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         (b) DUE AUTHORIZATION. Seller has all requisite corporate or
partnership power, as applicable, and authority to execute and deliver this
Agreement and to perform its obligations hereunder and to consummate the
transactions contemplated hereby. This Agreement has been duly authorized,
executed and delivered by Seller and constitutes a valid and binding
agreement of Seller enforceable against Seller in accordance with its terms.

         (c) ABSENCE OF DEFAULTS AND CONFLICTS. The execution, delivery and
performance of this Agreement by Seller and the consummation of the
transactions contemplated hereby do not and will not violate or be in
conflict with, or constitute a breach of or default (or an event which, with
notice or lapse of time or both, would constitute a default) under the terms
of any law, regulation, order, judgment, instrument, contract, license or
other agreement to which Seller is a party or by which Seller or its assets
are bound or which would prevent the consummation of this transaction, and no
consent or approval of any third party or any government, state, province,
county or other political subdivision thereof, or any entity exercising
executive, legislative, judicial, regulatory or administrative function of,
or pertaining to, governing (collectively, "Governmental Authority") is
necessary in order to permit Seller to execute and deliver this Agreement and
perform the transactions contemplated hereby.

         (d) TITLE TO INTEREST. Prior to the conversion and/or exchange of
the Securities into the Common Shares, the Seller has not sold, transferred,
pledged or otherwise disposed of, or converted or exchanged, or granted any
option or other right with respect to, any of the Securities and Seller has
good and marketable title to the Securities free and clear of all Liens. Upon
conversion of the Securities into the Common Shares, Seller will have good
and marketable title to the Common Shares, Seller will not have sold,
transferred, pledged or otherwise disposed of, or converted or exchanged, or
granted any option or other right with respect to the Common Shares and
Seller will convey to Buyer good, valid and marketable title to the Common
Shares free and clear of all Liens.

         (e) BROKERS. Seller has not employed any broker or finder or
incurred any liability for any brokerage fees or commissions in connection
with the transactions contemplated by this Agreement.

         (f) LITIGATION. There is no suit, claim, action, proceeding or
investigation pending or, to the Seller's knowledge, threatened against the
Seller or its affiliates or any of their predecessors with respect to the
Securities at law or in equity or before any Governmental Authority or before
any arbitrator of any kind and, to the Seller's knowledge, there is no
reasonable basis for any such suit, claim, action, proceeding or
investigation. The Seller has not been a party to any such suit, claim,
action, proceeding or investigation during the past two years relating to the
Securities, nor has any such suit, claim, action, proceeding or investigation
been threatened in writing by or against the Seller.


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         (g) REGULATION M. Seller acknowledges that neither the Buyer nor any
of its agents or affiliates solicited the sale of the Securities by Seller
and that the transactions contemplated hereby qualify as an "unsolicited
purchase" under Rule 102 of Regulation M promulgated under the rules and
regulations of the Securities Act of 1933, as amended.

         4. REPRESENTATIONS AND WARRANTIES OF BUYER. Buyer hereby represents
and warrants to each Seller that each of the following statements is true and
correct as of the date hereof and will be true and correct as of the Closing
Date as if made on such date.

         (a) GOOD STANDING AND DUE AUTHORIZATION. Buyer is duly organized,
validly existing and in good standing in the state of its incorporation, with
full trust power and authority to carry on its business as it is now operated
and carried on by it. Buyer has all requisite trust power and authority to
execute and deliver this Agreement and to perform its obligations hereunder
and to consummate the transactions contemplated hereby. This Agreement has
been duly authorized, executed and delivered by Buyer and constitutes a valid
and binding agreement of Buyer enforceable against Buyer in accordance with
its terms.

         (b) ABSENCE OF DEFAULTS AND CONFLICTS. The execution, delivery and
performance of this Agreement by Buyer and the consummation of the
transactions contemplated hereby do not and will not violate or be in
conflict with, or constitute a breach of or default (or an event which, with
notice or lapse of time or both, would constitute a default) under the terms
of any law, regulation, order, judgment, instrument, contract, license or
other agreement to which Buyer is a party or by which Buyer or its assets are
bound or which would prevent the consummation of this transaction, and no
consent or approval of any Governmental Authority is necessary in order to
permit Buyer to execute and deliver this Agreement and perform the
transactions contemplated hereby.

         (c) BROKERS. Buyer has not employed any broker or finder or incurred
any liability for any brokerage fees or commissions in connection with the
transactions contemplated by this Agreement.

         5. COVENANTS.

         (a) From the date hereof until the Closing Date, each Seller will
not, and will direct its employees, agents and other representatives
(including, without limitation, any financial advisor, attorney or accountant
retained by such Seller) not to, directly or indirectly, solicit, encourage,
or participate in any way in discussions or negotiations with, or provide any
information, data or assistance to, any third party (other than Buyer and its
affiliates) concerning any acquisition of, or other transaction involving,
the Securities. Each Seller will promptly communicate to Buyer in writing the
terms of any proposal or contact it may receive in respect of any such
transaction.

         (b) Each party to this Agreement shall execute and deliver, or cause
to be executed and delivered, all such instruments and shall take all such
actions as the other party may reasonably request in order to effect the
intent and purposes of and to carry out the terms of this Agreement.

         (c) Each Seller shall give Buyer and its authorized representatives,
at all reasonable times during regular business hours and on reasonable
advance notice, access to all information


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reasonably available to it which is necessary to Buyer to enable Buyer to
evaluate the merits and risks of purchasing the Securities.

         (d) Each Seller shall not sell, transfer, pledge or otherwise
dispose of, or convert or exchange, or grant any option or other right with
respect to, any of the Securities.

         6. SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All representations
and warranties contained or made in, or in connection with, this Agreement
shall survive the purchase and sale of the Common Shares, notwithstanding any
investigation conducted with respect thereto or any knowledge acquired as to
the accuracy or inaccuracy of any such representation or warranty.

         7. INDEMNIFICATION.

         (a) Each Seller, jointly and severally, agrees to defend, indemnify
and hold harmless Buyer, and its trustees, officers, employees, agents and
any of their successors and assigns, from and against any and all losses,
damages, claims, suits, proceedings, liabilities, costs and expenses
(including settlement costs, interest, penalties, reasonable attorney's fees
and any reasonable legal or other expenses for investigation or defense of
any actions or threatened actions) (collectively, "Losses" or "Claims," as
the context requires) which may be imposed, sustained, incurred or suffered
or asserted as a result of, relating to or arising out of (i) the breach of
any representation or warranty of such Seller contained in this Agreement;
(ii) any failure by such Seller to perform any covenant, agreement or
obligation of Seller contained in this Agreement; and (iii) such Seller's
ownership of the Securities prior to the Closing Date, including liabilities
for taxes, charges, fees and periodic deposits (including interest and
penalties) determined to have been due to any Governmental Authority during
the period that such Seller owned or held the Securities.

         (b) Buyer agrees to defend, indemnify and hold harmless each Seller
and its partners, officers, directors, employees, agents and any of their
successors and assigns from and against any and all Losses or Claims which
may be imposed, sustained, incurred or suffered or asserted as a result of,
relating to or arising out of (i) the breach of any representation or
warranty of Buyer contained in this Agreement; and (ii) any failure by Buyer
to perform any covenant, agreement or obligation of Buyer contained in this
Agreement.

         8. CONFIDENTIALITY. All information furnished in writing by one
party to this Agreement to another party to this Agreement in connection with
this Agreement and the transactions contemplated hereby shall be kept
confidential by the receiving party and shall be used by the receiving party
only in connection with this Agreement and the transactions contemplated
hereby, except to the extent that such information (i) is information which
the receiving party can demonstrate was already known to the receiving party
when received; (ii) thereafter becomes lawfully obtainable from other sources
through no act or failure to act on the part of the receiving party; or (iii)
is required to be disclosed pursuant to applicable law, rules or regulations
(including the Securities Exchange Act of 1934, as amended and the rules and
regulations thereunder or the rules of any stock exchange), provided, that
the receiving party shall disclose only so much of the confidential
information as is legally required.


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         9. MISCELLANEOUS.

         (a) All fees and expenses incurred in connection with this Agreement
and the transactions contemplated hereby, including all fees of counsel and
accountants, shall be paid by the party incurring the same.

         (b) This agreement may be terminated by the Sellers and the
transactions contemplated by it abandoned by notice from the Sellers to Buyer
if the Closing does not occur on the Closing Date, provided, however, that
the right to terminate this Agreement shall not be available if the Sellers'
breach of this Agreement has been the cause of the failure of the Closing to
occur on the Closing Date.

         (c) All notices, requests, demands and other communications required
or permitted under this Agreement shall be in writing and shall be delivered
personally, sent facsimile transmission, or sent next-day delivery via
Federal Express or a similar overnight courier. All communications to the
Sellers hereunder should be sent to Reckson Associates Realty Corp., 225
Broadhollow Road, Melville, New York 11747, Attn: Scott H. Rechler,
telephone: (631) 694-6900, facsimile: (631) 622-6788, with a copy to J.
Gerard Cummins, Sidley Austin Brown & Wood LLP, One World Trade Center, New
York, New York 10048, telephone: (212) 839-5300, facsimile: (212) 839-5599 or
to such other person or address as the Seller shall furnish to Buyer in
writing. All communications to Buyer hereunder should be sent to Keystone
Property Trust, 200 Four Falls Corporate Center, Suite 208, West
Conshohocken, Pennsylvania 19428, Attn: General Counsel, telephone: (484)
530-1800, facsimile: (484) 530-0131, with a copy to Clifford Chance Rogers &
Wells LLP, 200 Park Avenue, New York, NY 10166, Attn: Robert E. King, Jr.,
Esq., telephone: (212) 878-8000, facsimile: (212) 878-8375.

         A notice shall be deemed given for purposes of this Agreement (i) on
the date of delivery, if delivered personally or sent by facsimile transmission,
and (ii) on the first business day following the date of dispatch if sent
next-day delivery via Federal Express or similar a overnight courier. Any party
may change the address to which notices are to be sent by giving written notice
of such change of address to the other parties in the manner above provided for
giving notice.

         (d) THIS AGREEMENT SHALL BE CONSTRUED IN ACCORDANCE WITH AND
GOVERNED BY THE LAWS OF NEW YORK (WITHOUT GIVING EFFECT TO ANY CONFLICTS OR
CHOICE OF LAWS PROVISIONS THAT WOULD CAUSE THE APPLICATION OF THE DOMESTIC
SUBSTANTIVE LAWS OF ANY OTHER JURISDICTION).

         (e) This Agreement may not be amended, modified, superseded,
cancelled, renewed or extended except by a written instrument signed by both
Buyer and Seller; provided, that Buyer may assign its rights under this
Agreement to the Operating Partnership.

         (f) If any one or more of the covenants, agreements, provisions or
terms of this Agreement shall be held invalid, then such covenants,
agreements, provisions or terms shall be deemed severable from the remaining
covenants, agreements, provisions or terms of this Agreement and inoperative
to the extent it may conflict with any applicable statute or rule of law


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and shall be deemed modified to conform with such statute or rule of law and
shall in no way affect the validity or enforceability of the other provisions
of this Agreement or the rights of the parties hereto.

         (g) This Agreement may be executed simultaneously in two or more
identical counterparts, each of which shall be deemed an original, but all of
which together shall constitute one and the same instrument.

         (h) EACH OF THE PARTIES HERETO HEREBY VOLUNTARILY AND IRREVOCABLY
WAIVES TRIAL BY JURY IN ANY ACTION OR OTHER PROCEEDING BROUGHT IN CONNECTION
WITH THIS AGREEMENT, ANY OF THE OTHER TRANSACTION DOCUMENTS OR ANY OF THE
TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY.

         (i) Each party hereto further agrees that, at any time and from time
to time, upon the written request of the other party hereto, it will execute
and deliver such further instruments and do such further acts and things
reasonably necessary, desirable or proper as the requesting party may
reasonably request in order to effect the purposes of this Agreement.


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         IN WITNESS WHEREOF, the parties have executed this Agreement, acting
their duly authorized agents, as of the date first above written.

                                       KEYSTONE PROPERTY TRUST


                                       By:
                                          --------------------------------------
                                          Name:  Robert F. Savage Jr.
                                          Title: Executive Vice President and
                                                 Chief Operating Officer



                                       RECKSON OPERATING PARTNERSHIP, L.P.


                                       By: Reckson Associates Realty Corp.,
                                           its general partner


                                       By:
                                          --------------------------------------
                                          Name:  Scott H. Rechler
                                          Title: Co-Chief Executive Officer



                                       RECKSON CONSTRUCTION GROUP, INC.


                                       By:
                                          --------------------------------------
                                          Name:  Gregg Rechler
                                          Title: President


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                                                                       EXHIBIT A

<Table>
<Caption>

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          SELLER                                    SECURITIES                               PURCHASE PRICE
--------------------------------------------------------------------------------------------------------------------

<S>                              <C>                                                        <C>
Reckson Operating Partnership,   803,871 shares of 9.75% Series B Preferred Stock           $17,936,371.69
L.P.                             of Keystone Property Trust (to be converted into
                                 common shares of beneficial interest of Keystone
                                 Property Trust prior to the Closing Date); and

                                 296,795 9.75% Series C Preferred Units of Limited
                                 Partnership of Keystone Operating Partnership,
                                 L.P. (to be converted into common units of                  $6,622,238.44
                                 limited partnership of Keystone Operating
                                 Partnership, L.P. which will be exchanged into
                                 common shares of beneficial interest of Keystone
                                 Property Trust prior to the Closing Date).
--------------------------------------------------------------------------------------------------------------------

Reckson Construction Group,      499,334 9.75% Series C Preferred Units of Limited          $11,141,389.87
Inc.                             Partnership of Keystone Operating Partnership,
                                 L.P. (to be converted into common units of
                                 limited partnership of Keystone Operating
                                 Partnership, L.P. which will be exchanged into
                                 common shares of beneficial interest of Keystone
                                 Property Trust prior to the Closing Date).
--------------------------------------------------------------------------------------------------------------------
</Table>