Document:

<PAGE>

                             CONTRIBUTION AGREEMENT

                                     between

                 PRENTISS PROPERTIES ACQUISITION PARTNERS, L.P.,
                         a Delaware limited partnership

                                  ("Prentiss")

                                       and

                     BRANDYWINE OPERATING PARTNERSHIP, L.P.,
                         a Delaware limited partnership

                                ("Brandywine OP")

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                                TABLE OF CONTENTS

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ARTICLE I - DEFINITIONS...........................................................................................3

   1.1.     Definitions...........................................................................................3

ARTICLE II - CONTRIBUTION AND ISSUANCE; STUDY PERIOD; PROPERTY SUBJECT TO MASS MUTUAL LOAN.......................11

   2.1.     Contribution.........................................................................................11
   2.2.     Issuance of the Common Units and the Special Units...................................................12
   2.3.     Deposit..............................................................................................12
   2.4.     Study Period.........................................................................................13

ARTICLE III - BRANDYWINE OP'S REPRESENTATIONS AND WARRANTIES.....................................................18

   3.1.     Organization and Power...............................................................................18
   3.2.     Authorization, Execution and Disclosure..............................................................18
   3.3.     Non-contravention....................................................................................18
   3.4.     No Special Taxes.....................................................................................19
   3.5.     Compliance with Existing Laws and Restrictive Covenants..............................................19
   3.6.     Operating Agreements.................................................................................19
   3.7.     Condemnation Proceedings; Roadways...................................................................20
   3.8.     Actions or Proceedings...............................................................................20
   3.9.     Bankruptcy...........................................................................................20
   3.10.    Hazardous Substances.................................................................................20
   3.11.    Parties in Possession................................................................................21
   3.12.    Leases...............................................................................................21
   3.13.    Leased Property......................................................................................22
   3.14.    Personal Property....................................................................................22
   3.15.    Additional Representations and Warranties with Respect to the Tysons Partnership Interest and Tysons
             Partnership.........................................................................................22
   3.16.    No Unpaid Charges....................................................................................23
   3.17.    Condition of Improvements............................................................................23
   3.18.    Access...............................................................................................23
   3.19.    No Commitments.......................................................................................23
   3.20.    Not a "Foreign Person"...............................................................................23
   3.21.    Leasing Commissions..................................................................................24
   3.22.    Other Agreements.....................................................................................24
   3.23.    Existing Secured Indebtedness........................................................................24
   3.24.    Employment on "At-Will" Basis........................................................................24
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   3.25.    Additional Representations and Warranties with Respect to the Issuance of Common Units and Preferred
             Units...............................................................................................24
   3.26.    LIMITATIONS ON REPRESENTATIONS AND WARRANTIES........................................................25

ARTICLE IV - PRENTISS' REPRESENTATIONS AND WARRANTIES............................................................27

   4.1.     Organization and Power...............................................................................27
   4.2.     Non-contravention....................................................................................27
   4.3.     Litigation...........................................................................................27
   4.4.     Bankruptcy...........................................................................................28
   4.5.     Authorization, Execution and Disclosure..............................................................28
   4.6.     The Common Units.....................................................................................28
   4.7.     Allocation Methodology...............................................................................28

ARTICLE V - CONDITIONS PRECEDENT.................................................................................28

   5.1.     As to Prentiss' Obligations..........................................................................28
   5.2.     As to Brandywine OP's Obligations....................................................................30

ARTICLE VI - COVENANTS OF BRANDYWINE OP..........................................................................31

   6.1.     Operating Agreements.................................................................................31
   6.2.     Warranties and Guaranties............................................................................31
   6.3.     Insurance............................................................................................31
   6.4.     Operation of Property Prior to Closing...............................................................32
   6.5.     No Marketing.........................................................................................34

ARTICLE VII - CLOSING............................................................................................34

   7.1.     Closing..............................................................................................34
   7.2.     Brandywine OP's Deliveries...........................................................................34
   7.3.     Prentiss' Deliveries.................................................................................37
   7.4.     Mutual Deliveries....................................................................................38
   7.5.     Closing Costs........................................................................................38
   7.6.     Miscellaneous Payments and Revenue and Expense Allocations...........................................38

ARTICLE VIII - GENERAL PROVISIONS................................................................................40

   8.1.     Condemnation.........................................................................................40
   8.2.     Risk of Loss.........................................................................................41
   8.3.     Broker...............................................................................................41
   8.4.     8260 Greensboro......................................................................................41
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ARTICLE IX - LIABILITY OF PRENTISS; INDEMNIFICATION BY BRANDYWINE OP; DEFAULT; TERMINATION RIGHTS................42

   9.1.     Liability of Prentiss................................................................................42
   9.2.     Indemnification by Brandywine OP.....................................................................43
   9.3.     Default by Brandywine OP/Failure of Conditions Precedent.............................................43
   9.4.     Indemnification by Prentiss..........................................................................44
   9.5.     Default by Prentiss/Failure of Conditions Precedent..................................................44
   9.6.     Costs and Attorneys' Fees............................................................................45
   9.7.     Limitation of Liability..............................................................................45

ARTICLE X - MISCELLANEOUS PROVISIONS.............................................................................45

   10.1.    Completeness; Modification...........................................................................45
   10.2.    Assignments..........................................................................................45
   10.3.    Successors and Assigns...............................................................................45
   10.4.    Days.  46
   10.5.    Governing Law........................................................................................46
   10.6.    Counterparts.........................................................................................46
   10.7.    Severability.........................................................................................46
   10.8.    Notices..............................................................................................46
   10.9.    Escrow Agent.........................................................................................47
   10.10.   Incorporation by Reference...........................................................................48
   10.11.   Survival.............................................................................................48
   10.12.   Further Assurances...................................................................................48
   10.13.   No Partnership.......................................................................................48
   10.14.   Time of Essence......................................................................................48
   10.15.   Signatory Exculpation................................................................................48
   10.16.   Rules of Construction................................................................................49
   10.17.   SEC Reporting (8-K) Requirements.....................................................................49

EXHIBITS
Exhibit A -       Amended and Restated Tysons Partnership Agreement
Exhibit B -       FFI Consent
Exhibit C -       Management Agreement Assignment and Assumption Agreement
Exhibit D-1 -     Mass Mutual Consent
Exhibit D-2 -     Mass Mutual Loan Documents
Exhibit E -       Partnership Assignment and Assumption Agreement
Exhibit F -       Replacement Exchange Agreement
Exhibit G -       Replacement Registration Rights Agreement
Exhibit H -       Form of Fourteenth Amendment to Prentiss Partnership Agreement
Exhibit I -       Form of Termination Agreement
Exhibit J -       [Intentionally Omitted]
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Exhibit K -       Tenant Estoppel
Exhibit L -       Mass Mutual Estoppel
Exhibit M -       Excluded Personal Property

SCHEDULES
Schedule 3.6 -    Assumed Operating Agreements
Schedule 3.12 -   Rent Roll and Accounts Receivable Report
Schedule 3.19 -   Outstanding Leasing Commissions
Schedule 6.4(g) - Approved New Leases
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                                      -iv-

<PAGE>

                             CONTRIBUTION AGREEMENT

         THIS CONTRIBUTION AGREEMENT (this "Agreement") is made as of this 14th
day of March, 2001, between PRENTISS PROPERTIES ACQUISITION PARTNERS, L.P., a
Delaware limited partnership ("Prentiss"), and BRANDYWINE OPERATING PARTNERSHIP,
L.P., a Delaware limited partnership ("Brandywine OP").

                             R E C I T A T I O N S:

         A. Brandywine OP is the owner of a partnership interest (the "Tysons
Partnership Interest") in Brandywine Tysons International Partners, a Delaware
general partnership (the "Tysons Partnership") as more particularly described in
that certain Partnership Agreement dated as of September 14, 1999 (the "Original
Tysons Partnership Agreement") between Brandywine OP and FFI Tysons Partners,
L.P. (formerly known as Baita Tysons Partners, L.P.), a Georgia limited
partnership ("Baita").

         B. Under the Original Tysons Partnership Agreement, Brandywine OP is
the Managing Partner and, as such Managing Partner, Brandywine OP has caused the
Tysons Partnership to enter into that certain Management and Leasing Agreement
(the "Management Agreement") dated as of September 14, 1999 with Brandywine
Realty Services Corporation, an affiliate of Brandywine OP ("BRSCO").

<PAGE>

         C. Tysons Partnership is the indirect owner (through two subsidiary
limited partnerships, being Brandywine Tysons, L.P. and Brandywine 1676, L.P.)
of two properties (collectively, the "Property") situate at, and known as, 8260
Greensboro Drive, Tysons Corner, Virginia ("8260 Greensboro") and 1676
International Drive, Tysons Corner, Virginia ("1676 International") and as more
particularly described in Exhibit A to the Original Tysons Partnership
Agreement.

         D. Brandywine OP is desirous of contributing, and Prentiss is desirous
of accepting, the Tysons Partnership Interest, and Prentiss is also desirous of
replacing Brandywine OP as the Managing Partner of the Tysons Partnership and of
having the Management Agreement assigned to one of its affiliates by BRSCO, all
under the terms and conditions described herein.

         NOW, THEREFORE, in consideration of the foregoing premises and in
consideration of the mutual covenants, promises and undertakings of the parties
hereinafter set forth, and for other good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged by the parties, it is
agreed:

                                      -2-

<PAGE>

                                    ARTICLE I
                                   DEFINITIONS

         1.1. Definitions. The following terms shall have the indicated
meanings:

         "Act of Bankruptcy" shall mean if a party hereto or any general partner
thereof shall (a) apply for or consent to the appointment of, or the taking of
possession by, a receiver, custodian, trustee or liquidator of itself or of all
or a substantial part of its property, (b) admit in writing its inability to pay
its debts as they become due, (c) make a general assignment for the benefit of
its creditors, (d) file a voluntary petition or commence a voluntary case or
proceeding under the Federal Bankruptcy Code (as now or hereafter in effect),
(e) be adjudicated a bankrupt or insolvent, (f) file a petition seeking to take
advantage of any other law relating to bankruptcy, insolvency, reorganization,
winding-up or composition or adjustment of debts, (g) fail to controvert in a
timely and appropriate manner, or acquiesce in writing to, any petition filed
against it in an involuntary case or proceeding under the Federal Bankruptcy
Code (as now or hereafter in effect), or (h) take any corporate or partnership
action for the purpose of effecting any of the foregoing; or if a proceeding or
case shall be commenced, without the application or consent of a party hereto or
any general partner thereof, in any court of competent jurisdiction seeking (1)
the liquidation, reorganization, dissolution or winding-up, or the composition
or readjustment of debts, of such party or general partner, (2) the appointment
of a receiver, custodian, trustee or liquidator for such party or general
partner or all or any substantial part of its assets, or (3) other similar
relief under any law relating to bankruptcy, insolvency, reorganization,
winding-up or composition or adjustment of debts, and such proceeding or case
shall continue undismissed for a period of ninety (90) consecutive days; or an
order (including an order for relief entered in an involuntary case under the
Federal Bankruptcy Code, as now or hereafter in effect) judgment or decree
approving or ordering any of the foregoing shall be entered and continue
unstayed and in effect, for a period of ninety (90) consecutive days.

         "Additional Special Distribution" shall have the meaning set forth in
Section 11.4 of the Original Tysons Partnership Agreement.

         "Amended and Restated Tysons Partnership Agreement" shall mean an
Amended and Restated Partnership Agreement in the form attached hereto and made
a part hereof as Exhibit A, which Prentiss and FFI will execute in connection
with the Closing.

         "Applicable Laws" shall mean any applicable building, zoning,
subdivision, environmental, health, safety or other governmental laws, statutes,
ordinances, resolutions, rules, codes, regulations, orders or determinations of
any Governmental Authority or of any insurance boards of underwriters (or other
body exercising similar functions), or any restrictive covenants or deed
restrictions affecting the Property or the ownership, operation, use,
maintenance or condition thereof.

         "Applicable Share Price" shall mean the average closing price of the
Common Shares during the thirty trading days ending on the last trading day
prior to the Closing Date.

                                      -3-
<PAGE>

         "Assignment and Assumption Agreement" shall mean one or more agreements
whereby (a) Brandywine OP indemnifies, defends and holds Prentiss harmless with
respect to all defaults, liabilities, claims, costs and expenses (including,
without limitation, reasonable attorneys' fees) relating to acts or omissions
accruing under the Assumed Operating Agreements before the Closing Date (but
excluding, in any event, ordinary course accruals); and (b) Prentiss (directly
or through Tysons Partnership) indemnifies, defends and holds Brandywine OP
harmless with respect to all defaults, liabilities, claims, costs and expenses
(including, without limitation, reasonable attorneys' fees) relating to acts or
omissions accruing under such the Assumed Operating Agreements after the Closing
Date.

         "Assignment of Leases" shall mean the agreement whereby (a) Brandywine
OP indemnifies, defends and holds Prentiss harmless with respect to all
defaults, liabilities, claims, costs and expenses (including, without
limitation, reasonable attorneys' fees) relating to acts or omissions accruing
under such Leases before the Closing Date (but excluding, in any event, ordinary
course accruals); and (b) Prentiss (directly or through Tysons Partnership)
indemnifies, defends and holds Brandywine OP harmless with respect to all
defaults, liabilities, claims, costs and expenses (including, without
limitation, reasonable attorneys' fees) relating to acts or omissions accruing
under such Leases after the Closing Date.

         "Assumed Operating Agreements" shall mean the Operating Agreements
listed on Schedule 3.6 hereto which are not to be terminated pursuant to the
last sentence of Section 3.6 hereof.

         "Authorizations" shall mean all licenses, permits and approvals
required by any governmental or quasi-governmental agency, body, department,
commission, board, bureau, instrumentality or officer, any owners association
created pursuant to deed restrictions affecting the Property or otherwise
appropriate with respect to the construction, ownership, operation, leasing,
maintenance, or use of the Property or any part thereof.

         "Brandywine OP" shall mean Brandywine Operating Partnership, L.P., a
Delaware limited partnership.

         "Brandywine OP's Organizational Documents" shall mean the
organizational documents and all amendments thereto of Brandywine OP.

         "Closing" shall mean the Closing of the contribution of the Tysons
Partnership Interest and the issuance of the Common Units and the Special Units
pursuant to this Agreement and shall be deemed to occur on the Closing Date.

         "Closing Date" shall mean the date on which the Closing occurs.

         "Closing Documents" shall mean the documents defined as such in Section
7.1 hereof.

         "Code" shall mean the federal Internal Revenue Code of 1986, as
amended.

                                      -4-
<PAGE>

         "Common Units" shall mean Common Units of Limited Partnership interests
in Prentiss.

         "Common Shares" shall mean common shares of beneficial interest in the
Trust which, when and if issued upon redemption of Common Units, will be issued
in accordance with the Prentiss Partnership Agreement, including the Fourteenth
Amendment thereto.

         "Deposit" shall mean all amounts deposited from time to time with
Escrow Agent by Prentiss pursuant to Section 2.3 hereof, plus all interest or
other earnings that may accrue thereon. All cash Deposits shall be invested by
Escrow Agent in a commercial bank or banks acceptable to Prentiss at money
market rates, or in such other investments as shall be approved in writing by
Prentiss and Brandywine OP. The Deposit shall be held and disbursed by Escrow
Agent in strict accordance with the terms and provisions of this Agreement.

         "Environmental Damages" shall mean all third-party claims, judgments,
damages, losses, penalties, fines, liabilities (including, without limitation,
punitive damages and strict liability), encumbrances, liens, costs and expenses
of investigation and defense of any claim, whether or not such is ultimately
defeated, and of any settlement or judgment, of whatever kind or nature,
contingent or otherwise, matured or unmatured, including, without limitation,
attorneys' fees and disbursements and consultants' fees, any of which arise as a
result of the existence of Hazardous Materials upon, about or beneath the
Property or migrating or threatening to migrate from the Property, or as a
result of the existence of a violation of Environmental Requirements pertaining
to the Property.

         "Environmental Requirements" shall mean (i) all applicable statutes,
regulations, rules, policies, ordinances, codes, licenses, permits, orders,
approvals, plans, authorizations, and similar items, of all Governmental
Authorities, and (ii) all judicial, administrative and regulatory decrees,
judgments and orders, in each case of (i) and (ii) relating to the protection of
human health or the environment from Hazardous Materials and health and safety
of employees or the public from Hazardous Materials, including, without
limitation, all requirements thereof pertaining to reporting, licensing,
permitting, investigation and remediation of emissions, discharges, releases or
threatened releases of Hazardous Materials into the air, surface water,
groundwater or land, or relating to the manufacture, processing, distribution,
use, treatment, storage, disposal, transport or handling of Hazardous Materials.

         "Escrow Agent" shall mean Chicago Title Insurance Company.

         "Excluded Personal Property" shall mean those items of personal
property identified on Exhibit M. For clarity, the items identified on Exhibit M
consist of items that neither Brandywine OP nor BRSCO contributed to Tysons
Partnership or a Subsidiary Entity (nor were any of such items purchased by
Tysons Partnership or a Subsidiary Entity) but which, in furtherance of services
which BRSCO has performed for the Property, have been used at the Property.

                                      -5-
<PAGE>

         "FFI" shall mean FFI Tysons Partners, L.P. (formerly Baita Tysons
Partners, L.P.), a Georgia limited partnership.

         "FFI Consent" shall mean a document evidencing FFI's consent to the
transactions contemplated by this Agreement, in substantially the form attached
hereto as Exhibit B.

         "FIRPTA Certificate" shall mean the affidavit of Brandywine OP under
Section 1445 of the Code, as amended, certifying that neither Brandywine OP,
Tysons Partnership nor any of the Subsidiary Entities is a foreign corporation,
foreign partnership, foreign trust, foreign estate or foreign person (as those
terms are defined in the Code and regulations promulgated thereunder), in form
and substance satisfactory to Prentiss.

         "Fourteenth Amendment" shall mean the Fourteenth Amendment to the
Prentiss Partnership Agreement.

         "Governmental Authority" shall mean any federal, state, county,
municipal or other government or any governmental or quasi-governmental agency,
department, commission, board, bureau, officer or instrumentality, foreign or
domestic, or any of them.

         "Hazardous Materials" shall mean any chemical substance: (i) which is
or becomes defined as a "hazardous substance," "hazardous waste," "hazardous
material," "pollutant," "contaminant," or "toxic," "explosive," "corrosive,"
"flammable," "infectious," "radioactive," "carcinogenic," or "mutagenic"
material under any law, regulation, rule, order, or other authority of the
federal, state or local governments, or any agency, department, commission,
board, or instrumentality thereof, regarding the protection of human health or
the environment from such chemical substances including, but not limited to, the
following federal laws and their amendments, analogous state and local laws, and
any regulations promulgated thereunder: the Clean Air Act, the Clean Water Act,
the Oil Pollution Control Act, the Comprehensive Environmental Response,
Compensation, and Liability Act of 1986, the Emergency Planning and Community
Right to Know Act, the Solid Waste Disposal Act, the Resource Conservation and
Recovery Act, the Safe Drinking Water Act, the Federal Insecticide, Fungicide
and Rodenticide Act, and the Toxic Substances Control Act, including, without
limitation, asbestos and gasoline and other petroleum products (including crude
oil or any fraction thereof); (ii) without limitation, which contains gasoline,
diesel fuel or other petroleum hydrocarbons; (iii) without limitation, which
contains asbestos-containing materials or urea formaldehyde foam insulation; or
(iv) without limitation, radon gas; provided, however, the term "Hazardous
Materials" shall not include de minimis quantities of substances of kinds and in
amounts ordinarily and customarily used or stored in properties similar to the
Property for the purposes of cleaning or other maintenance or operations and
otherwise in compliance with Environmental Requirements.

         "Improvements" shall mean all buildings, improvements, fixtures and
other items of real estate located on 8260 Greensboro and 1676 International.

                                      -6-
<PAGE>

         "Insurance Policies" shall mean all policies of insurance maintained by
or on behalf of Brandywine OP, Tysons Partnership and/or the Subsidiary Entities
pertaining to the Property, its operation, or any part thereof.

         "Intangible Personal Property" shall mean all intangible personal
property owned or possessed by Tysons Partnership or a Subsidiary Entity and
used in connection with the ownership, operation, leasing, occupancy or
maintenance of the Property, including, without limitation, (1) Tysons
Partnership's exclusive right to use any trade names associated with the
Property and all variations thereof (other than variants of the legal name of
Brandywine OP, Brandywine Realty Trust or FFI, all rights to which shall be
retained by Brandywine OP, Brandywine Realty Trust, FFI or their respective
affiliates), (2) the Authorizations, utility and development rights and
privileges, general intangibles, business records, plans and specifications
pertaining to the Property and the Personal Property, and (3) any unpaid award
for taking by condemnation or any damage to the Parcels by reason of a change of
grade or location of or access to any street or highway.

         "Leased Property" shall mean all leased items of Personal Property.

         "Leases" shall mean all leases, tenancies and other rights of occupancy
or use for any portion of the Property, together with any and all amendments
thereto.

         "Management Agreement Assignment and Assumption Agreement" shall mean
an assignment and assumption agreement in substantially the form attached hereto
as Exhibit C whereby (a) BRSCO (1) assigns and Manager assumes the Management
Agreement and the rights and obligations of BRSCO with respect thereto, and (2)
indemnifies, defends and holds Manager and its agents, employees, officers,
directors, shareholders and contractors harmless with respect to all defaults,
liabilities, claims, costs and expenses (including, without limitation,
reasonable attorneys' fees) relating to acts or omissions by BRSCO accruing with
respect to such Management Agreement before the Closing Date; (b) the assignor
and assignee apportion fees due thereunder as of the Closing Date as provided in
Section 7.6 hereof; and (c) Manager indemnifies, defends and holds BRSCO
harmless with respect to all defaults, liabilities, claims, costs and expenses
(including, without limitation, reasonable attorneys' fees) relating to acts or
omissions accruing with respect to such Management Agreement after the Closing
Date.

         "Manager" shall mean Prentiss Properties Management, L.P., a Texas
limited partnership.

         "Mass Mutual" shall mean Massachusetts Mutual Life Insurance Company.

         "Mass Mutual Consent" shall mean a document evidencing Mass Mutual's
consent to the transactions contemplated by this Agreement in substantially the
form attached as Exhibit D-1.

         "Mass Mutual Loans" shall mean those certain mortgage loans secured by
the Property in the initial aggregate principal amount of $61.5 million.

                                      -7-
<PAGE>

         "Mass Mutual Loan Documents" shall mean those certain loan documents
scheduled on Exhibit D-2 attached hereto and made a part hereof.

         "NYSE" shall mean the New York Stock Exchange.

         "Operating Agreements" shall mean all management, service, supply and
maintenance contracts, if any, in effect with respect to the Property and all
other contracts (other than the Leases) that affect the Property or are
otherwise related to the construction, ownership, operation, occupancy or
maintenance of the Property.

         "Original Exchange Agreement" shall mean the Exchange Agreement dated
as of September 14, 1999 between Brandywine OP and FFI.

         "Original Non-Recourse Guaranty" shall mean collectively the two
Non-Recourse Guaranty agreements executed by Brandywine OP in favor of Mass
Mutual and which are part of the Mass Mutual Loan Documents.

         "Original Registration Rights Agreement" shall mean the Registration
Rights Agreement dated as of September 14, 1999 among Brandywine OP, Brandywine
Realty Trust and Baita.

         "Original True Up" shall mean that certain letter agreement between
Brandywine OP and Baita dated as of September 14, 1999.

         "Owner's Title Policy" shall mean an owner's policy of title insurance
for the Property issued to Prentiss by the Title Company, pursuant to which the
Title Company insures ownership of fee simple title to the Property by the
applicable Subsidiary Entities subject only to Permitted Title Exceptions. The
Owner's Title Policy shall be acceptable in form and substance to Prentiss.
Prentiss may require such deletions of standard exceptions and such title
endorsements as are legally available and customarily required by institutional
investors purchasing property comparable to the Property in the Commonwealth of
Virginia, including a non-imputation endorsement. The legal descriptions in the
Owner's Title Policy shall be by courses and distances or by reference to a
legal, subdivided lot and shall be identical to the description shown on the
Survey.

         "Parcel" shall mean each individual tract of the Property.

         "Partnership Assignment and Assumption Agreement" shall mean an
assignment and assumption agreement in substantially the form attached hereto as
Exhibit E whereby (a) Brandywine OP (1) contributes and assigns and Prentiss
accepts and assumes the Tysons Partnership Interest, free of liens and
encumbrances, and the rights and obligations of Brandywine OP with respect
thereto, and (2) indemnifies, defends and holds Prentiss and its agents,
employees, officers, directors, partners, shareholders and contractors harmless
with respect to all defaults, liabilities, claims, costs and expenses
(including, without limitation, reasonable attorneys' fees) (but in any event
excluding ordinary course accruals) relating to acts

                                      -8-
<PAGE>

or omissions accruing with respect to the Tysons Partnership Interest or
Brandywine OP before the Closing Date; and (b) Prentiss indemnifies, defends and
holds Brandywine OP harmless with respect to all defaults, liabilities, claims,
costs and expenses (including, without limitation, reasonable attorneys' fees)
relating to acts or omissions accruing solely with respect to the Tysons
Partnership Interest, the Property, Tyson Partnership and the Subsidiary
Entities after the Closing Date.

         "Permitted Title Exceptions" shall mean the Mass Mutual Loan Documents
(and the mortgages and other liens arising thereunder) and those exceptions to
title to the Real Property that are satisfactory to Prentiss as determined
pursuant to Section 2.4(c) hereof.

         "Personal Property" shall mean collectively the Tangible Personal
Property and the Intangible Personal Property.

         "Prentiss Organizational Documents" shall mean the organizational
documents and all amendments thereto of Prentiss.

         "Prentiss Securities" shall mean, collectively, the Common Units and
Special Units.

         "Prentiss Partnership Agreement" shall mean the Second Amended and
Restated Partnership Agreement, as amended, of Prentiss.

         "Property" shall mean collectively the Parcels and Improvements located
thereon.

         "Rent Roll" shall have the meaning ascribed to such term in Section
2.4(b)(2) of this Agreement.

         "Replacement Exchange and Registration Rights Agreements" shall mean
those certain Exchange Agreement and Registration Rights Agreement in the form
attached hereto, and made a part hereof, as Exhibits F and G.

         "Replacement True Up" shall mean a letter agreement between Prentiss
and Baita substantially in the form of the Original True Up.

         "Securities Act" shall mean the Securities Act of 1933, as amended.

         "Special Units" shall mean those certain 7.5% Series E Cumulative
Redeemable Preferred Units, in the form included in the Fourteenth Amendment to
the Prentiss Partnership Agreement attached hereto, and made a part hereof, as
Exhibit H, having an aggregate stated value in the amount of $10,000,000.

         "Study Period" shall mean the period commencing on the date this
Agreement has been fully executed and delivered by all parties hereto, and
continuing through February 16,

                                      -9-
<PAGE>

2001. Except as expressly noted herein to the contrary, time periods herein
referred to shall mean the time periods as in effect, from time to time, at
Dallas, Texas.

         "Submission Matters" shall mean all items Brandywine OP is required to
deliver to Prentiss pursuant to Section 2.4(b) hereof.

         "Subsidiary Entities" shall mean Brandywine Tysons, L.P., a Delaware
limited partnership (the owner of 8260 Greensboro), Brandywine 1676, L.P., a
Delaware limited partnership (the owner of 1676 International) and Brandywine
Tysons, L.L.C., a Delaware limited liability company (the general partner of
Brandywine Tysons, L.P. and Brandywine 1676, L.P.).

         "Substitute Non-Recourse Guaranty" shall mean collectively the two
Non-Recourse Guaranty agreements substantially in form of the Original
Non-Recourse Guaranty, which Prentiss will execute and deliver to Mass Mutual as
part of the Closing hereunder.

         "Survey" shall mean the surveys defined as such in and prepared
pursuant to Section 2.4(c) hereof.

         "Tangible Personal Property" shall mean the items of tangible personal
property consisting of all furniture, fixtures, equipment, machinery and other
personal property of every kind and nature located on or used or useful in the
ownership and operation of the Property and owned by Tysons Partnership or a
Subsidiary Entity, including, without limitation, the interest as lessee of
Tysons Partnership or a Subsidiary Entity with respect to any such Tangible
Personal Property, other than the items of personal property identified on
Exhibit M hereto, the title to which is not being contributed or transferred
pursuant to this Agreement.

         "Termination Agreement" shall mean that certain Termination of Exchange
and Registration Rights Agreement in the form attached hereto, and made a part
hereof, as Exhibit I, and which will terminate the Original Exchange Agreement
and the Original Registration Rights Agreement.

         "Title Commitment" shall mean the title commitment and exception
documents defined as such in Section 2.4(c) hereof.

         "Title Company" shall mean Chicago Title Insurance Company or other
title insurance underwriter selected by Prentiss.

         "Trust" shall mean Prentiss Properties Trust, a Maryland real estate
investment trust.

         "UCC Reports" shall mean the reports defined as such in Section 2.4(d)
hereof.

         "Utilities" shall mean public sanitary and storm sewers, natural gas
(if any), telephone, public water facilities, electrical facilities and all
other utility facilities and services (if

                                      -10-
<PAGE>

any) necessary or appropriate for the operation and occupancy of the Property as
an office building.

         "Warranties and Guaranties" shall mean all warranties and guaranties
relating to the Improvements or any part thereof.

                                   ARTICLE II
                           CONTRIBUTION AND ISSUANCE;
               STUDY PERIOD; PROPERTY SUBJECT TO MASS MUTUAL LOAN

         2.1. Contribution.

                  (a) (i) On the Closing Date, Brandywine OP agrees to
contribute, free and clear of all liens and encumbrances, and Prentiss agrees to
accept, the Tysons Partnership Interest, including the right to receive the
outstanding balance on the Closing Date of the Additional Special Distribution
(which will be distributable in accordance with the terms of the Original Tysons
Partnership Agreement as the same may be amended on or after the Closing Date by
Prentiss and FFI), in accordance with and subject to the other terms and
conditions set forth herein. On the Closing Date, Brandywine OP shall cause
BRSCO to assign the Management Agreement to Manager and Prentiss shall cause
Manager to accept such assignment pursuant to the Management Agreement
Assignment and Assumption Agreement.

                  (ii) The distributions declared by Prentiss in respect of the
Common Units issuable pursuant to this Agreement during the initial calendar
quarter in which the Closing occurs shall be pro-rated by Prentiss based on the
number of days the Common Units are outstanding during such quarter. For
example, if the Common Units issuable pursuant to this Agreement were issued on
March 1, 2001, each of such Common Units would be entitled to receive an amount
equal to one-third of the amount of the distributions payable to a Common Unit
that was outstanding during the full quarter. There shall be no such adjustment
for the Special Units, which shall accrue distributions from the Closing Date.

                  (b) It is the intent of the parties to this Agreement that the
transaction qualify as a tax-deferred contribution by Brandywine OP to Prentiss
of the Tysons Partnership Interest under Section 721 of the Code with respect to
the receipt of Common Units and Special Units by Brandywine OP.

                  (c) Prentiss makes no representations and warranties regarding
the tax consequences to Brandywine OP of the transactions under this Agreement.

                  (d) The Common Units and Special Units to be issued by
Prentiss to Brandywine OP shall not be sold, pledged, hypothecated or otherwise
transferred by Brandywine OP for a period of two years from the Closing Date.

                                      -11-
<PAGE>

         2.2. Issuance of the Common Units and the Special Units.

                  (a) On the Closing Date, Prentiss shall issue, and Brandywine
OP shall accept, that number of Common Units which is equal to $650,000 divided
by the Applicable Share Price.

                  (b) On the Closing Date Prentiss shall issue, and Brandywine
OP shall accept, the Special Units in the aggregate stated value of $10,000,000.

                  (c) Prentiss acknowledges and agrees that the Property is
subject to the unpaid balances of the Mass Mutual Loans, and subject to the
mortgage and encumbrances securing the Mass Mutual Loans. Notwithstanding the
foregoing, (i) to the extent that any of the Mass Mutual Loan documents creates
personal liability for specified acts, omissions or occurrences (such acts,
omissions or occurrences being referred to as "Carve-Out Activities") and the
associated personal liability being referred to as "Carve-Out Liability"), (A)
Prentiss shall, if Closing occurs, be responsible for any such Carve-Out
Liability attributable to Carve-Out Activities accruing and occurring from and
after the Closing Date, and shall and does hereby indemnify and hold Brandywine
OP harmless with respect thereto, and (B) Brandywine OP shall and does hereby
indemnify and hold Prentiss harmless with respect to Carve-Out Liability
attributable to Carve-Out Activities of Brandywine OP accruing or occurring
prior to the Closing Date by virtue of acts or omissions of Brandywine OP. If
permitted by Mass Mutual, Brandywine OP shall be released from all Carve-Out
Liability under the Mass Mutual Loan Documents and Prentiss shall execute such
documents as Mass Mutual may reasonably require to evidence the assumption by
Prentiss of the Carve-Out Liability attributable to Carve-Out Activities of
Prentiss accruing and occurring from and after the Closing Date. The provisions
of this Section 2.2(c) shall survive the Closing.

                  (d) All items of taxable income or gain that are allocated to
Prentiss by the Tysons Partnership pursuant to Section 704(c) of the Code, as
well as any items of taxable income or gain recognized by Prentiss in respect of
the Tysons Partnership shall be allocated to Brandywine OP for federal income
tax purposes pursuant to Section 704(c) of the Code and the principles of Treas.
Reg. Section 1.704-3(a)(9) and Brandywine OP covenants to file its federal
income tax return in a manner consistent with the foregoing. Furthermore,
Brandywine OP will be allocated an amount of income equal to any gain recognized
by Prentiss upon the lapse of the Brandywine OP "bottom guaranty" of the $16.2
million Mass Mutual loan on January 5, 2004. The provisions of this Section
2.2(d) shall survive the Closing.

                  (e) The parties acknowledge that the fair market value of the
Tysons Partnership Interest is $10,650,000.

         2.3. Deposit. Within three (3) days after the execution hereof by both
Prentiss and Brandywine OP and as a condition precedent to the effectiveness of
this Agreement, Prentiss shall deliver to Escrow Agent a wire transfer or check
(a) in the sum of Fifty Dollars ($50.00) (the "Independent Consideration"),
payable to the order of Brandywine OP representing the

                                      -12-
<PAGE>

Independent Consideration for Prentiss' execution of this Agreement (which check
or the proceeds of which wire transfer shall thereafter be delivered by Escrow
Agent to Brandywine OP) and (b) in the sum of $300,000 (the proceeds of which
wire transfer or check Escrow Agent shall deposit and invest in an interest
bearing account at a financial institution acceptable to Prentiss or as
otherwise agreed to in writing by Prentiss and Brandywine OP). The proceeds of
the wire transfer or check are referred to herein as the "Deposit" and Escrow
Agent shall hold and invest the Deposit pursuant to the terms, conditions and
provisions of this Agreement. All accrued interest on the Deposit shall become
part of the Deposit. The Deposit (regardless of whether it is the proceeds of a
wire transfer or check) shall be either (a) returned to Prentiss pursuant
hereto, or (b) paid to Brandywine OP pursuant hereto. For purposes of reporting
earned interest with respect to the Deposit, Prentiss' Federal Tax
Identification Number is 75-2672997, and Brandywine OP's Federal Tax
Identification Number is 23-2862640.

         2.4. Study Period.

                  (a) Prentiss and its agents, contractors and duly authorized
representatives shall have the right, until 5:00 p.m., Dallas, Texas time on the
last day of the Study Period, and thereafter unless, as provided below, Prentiss
notifies Brandywine OP in writing prior to the expiration of the Study Period
that Prentiss has elected to terminate this Agreement, to enter upon the
Property and to perform, at its expense, such economic, surveying, engineering,
topographic, environmental, marketing and other tests, studies and
investigations as Prentiss may deem appropriate. If such tests, studies and
investigations do not warrant, in Prentiss' sole, absolute and unreviewable
discretion, the acceptance of the Tysons Partnership Interest for the purposes
contemplated by Prentiss, then Prentiss may elect not to proceed with this
transaction and shall notify Brandywine OP and Escrow Agent, in writing prior to
the expiration of the Study Period, that Prentiss has elected to terminate this
Agreement, in which event this Agreement automatically shall terminate, the
Deposit shall be promptly returned to Prentiss and Prentiss and shall be
released from all further liability or obligation hereunder except those which
expressly survive a termination of this Agreement. If Prentiss does not so
notify Brandywine OP of its determination to terminate this Agreement prior to
the expiration of the Study Period, then Prentiss shall be deemed to have waived
its right to terminate this Agreement pursuant to this Section 2.4.

                  (b) Brandywine OP has delivered or made available at the
Property the following to Prentiss:

                           (1) Copies of all Leases in effect as of the date of
this Agreement, together with, to the extent in Brandywine OP's possession or
reasonably available to Brandywine OP, copies of all correspondence received
from or sent to tenants of the Property.

                           (2) a Rent Roll (herein so called) certificate (with
current rent roll and accounts receivable report attached) for the Property
containing the following information with respect to each Lease: (i) a
description of the space occupied thereby (including square feet, type of space,
floor and tenant's pro rata share of common elements),

                                      -13-
<PAGE>

(ii) tenant's name, (iii) the commencement date and expiration date thereof,
(iv) the rental rate per square foot, (v) the amount of fixed monthly rental,
(vi) the amount of any percentage or other additional rental and/or common area
maintenance, tax, insurance and operating expenses and any other charges payable
thereunder and, if applicable, the base year used in each Lease, (vii) the
amount of any prepayment, (viii) the amount of the security deposit or any other
deposit thereunder, (ix) any free rent, concessions, rebates, refunds,
refurbishment allowances or other inducements which any tenant will be entitled
to receive after December 31, 2000 (including, without limitation, any of the
foregoing that may be payable in connection with renewals, extensions or
expansions expressly contemplated in any of such Leases), (x) any options
provided thereunder, including, without limitation, any renewal options,
expansion options, purchase options and rights of first refusal and (xi)
delinquency in rental or other charges set forth in the attached accounts
receivable report.

                           (3) To the extent in Brandywine OP's possession or
reasonably available to Brandywine OP, copies of all Authorizations including,
without limitation, all certificates of occupancy, permits, authorizations,
approvals (including drawings and enacting ordinances, if any), special
exceptions, variances, and licenses issued by Governmental Authorities having
jurisdiction over the Property and copies of all certificates issued by the
local board of fire underwriters (or other body exercising similar functions)
relating to the Property. For the purpose of this Agreement any Submission
Matters in the possession of Brandywine OP or BRSCO shall be deemed to be
"reasonably available to Brandywine OP."

                           (4) To the extent in Brandywine OP's possession or
reasonably available to Brandywine OP: (X) operating statements showing all
income and expenses, profits and losses of the Property for the previous three
(3) calendar years, which shall reflect (i) ad valorem taxes for the City,
County and Commonwealth; (ii) expenses incurred for such period for water,
electricity, natural gas and other utility charges; (iii) other operating
expenses; (iv) total rents collected from tenants for such periods; and (v)
other revenue collected and nature of such revenue; and (Y) financial statements
for the Property for the previous three (3) calendar years, including, if
available, the reports of accountants thereon.

                           (5) Operating and capital expenditure budgets for the
current calendar year and, to the extent in Brandywine OP's possession or
reasonably available to Brandywine OP, for the previous three (3) calendar
years.

                           (6) All existing surveys and title policies for the
Property that are reasonably available to Brandywine OP.

                           (7) A complete list of all Operating Agreements and
leasing commission agreements relating to the Property in effect as of the date
of this Agreement and complete copies of all such Operating Agreements and
leasing commission agreements.

                                      -14-
<PAGE>

                           (8) A complete list of all Tangible Personal Property
and a complete list of all Leased Property (if any) and complete copies of all
lease agreements related thereto.

                           (9) To the extent in Brandywine OP's possession or
reasonably available to Brandywine OP, any information in Brandywine OP's'
possession or reasonably available to Brandywine OP regarding current renditions
or assessments on the Property or notices relative to change in valuation for ad
valorem taxes.

                           (10) A complete list of all Warranties and Guaranties
in effect as of the date of this Agreement and complete copies of all such
Warranties and Guaranties.

                           (11) Copies of all soil tests, structural engineering
tests, inspection reports, asbestos surveys, masonry tests, percolation tests,
water, oil, gas, mineral, radon, formaldehyde, PCB or other environmental tests,
audits or reports, market studies and site plans related to the Property in
Brandywine OP's possession or reasonably available to Brandywine OP, together
with copies of any and all correspondence, reports and other written
documentation regarding the environmental aspects of the property or any toxic
substances or equipment affecting or related to the Property.

                           (12) If in Brandywine OP's possession or reasonably
available to Brandywine OP, copies of complete sets of all architectural,
mechanical, structural and/or electrical plans and specifications used in
connection with the construction of or alterations or repairs to the Property.

                           (13) If in Brandywine OP's possession or reasonably
available to Brandywine OP, copies of as-built plans and specifications for the
Property.

                           (14) Parking, structural, mechanical or other
engineering reports or studies related to the Property, if any, in Brandywine
OP's possession or reasonably available to Brandywine OP.

                           (15) To the extent in the possession of Brandywine OP
or any affiliate of Brandywine OP or BRSCO, copies of credit reports and
financial information on all tenants in possession of any of the Property and of
any guarantors of such tenants' obligations.

                           (16) Copies of all approvals from any owners
associations having jurisdiction over the Real Property and copies of all
correspondence from any such owners association.

                           (17) Copies of the Mass Mutual Loan Documents and
copies of any uncured notices of default or event of default from Mass Mutual.

                           (18) A copy of the tax return and financial
statements for Tysons Partnership for 1999 and 2000 to the extent reasonably
available to Brandywine OP.

                                      -15-
<PAGE>

                           (19) A copy of the Original Tysons Partnership
Agreement and the limited partnership agreements and limited liability company
agreement, as applicable, for the Subsidiary Entities to the extent reasonably
available to Brandywine OP.

                           (20) Copies of all Insurance Policies in effect,
together with the name and telephone number of a contact person at each
insurance company.

         Any reference to a document or information being in the possession of
Brandywine OP or similar phrase shall be construed to include documents or
information currently in the possession of Tysons Partnership, BRSCO or any of
the Subsidiary Entities.

         During the Study Period and thereafter until the Closing, Brandywine OP
shall make available to Prentiss, copies of all materials, correspondence,
books, records, financial statements, operating statements and any and all other
materials or information relating to the Property which come into Brandywine
OP's, Tysons Partnership's or either of the Subsidiary Entities' possession or
control or are otherwise reasonably available to Brandywine OP from and after
the date on which the Submission Matters were delivered to Prentiss.

         Notwithstanding anything herein to the contrary, although Prentiss has
not received all of the deliveries described in this Section 2.4(b), Prentiss
has completed its feasibility study pursuant to Section 2.4(a) but reserves the
right to require, and Brandywine OP hereby agrees to deliver, to the extent
available to it, any item described in Section 2.4(b) not previously delivered
at any time during the period expiring six (6) months after the Closing Date,
which agreement shall survive the Closing Date for such six (6) month period.

                  (c) Prentiss shall indemnify and defend Brandywine OP against
any loss, damage or claim for personal injury or property damage (including
reasonable attorney's fees) arising from the entry upon the Property pursuant to
this Section 2.4 by Prentiss or any agents, contractors or employees of
Prentiss. Prentiss, at its own expense, shall restore any damage to the Property
caused by any of the tests or studies made by Prentiss. This provision shall
survive any termination of this Agreement and a closing of the transaction
contemplated hereby.

                  (d) On or before 5:00 p.m. Dallas, Texas time on the date that
is five (5) days after the date of this Agreement, Brandywine OP shall deliver
to Prentiss, at Brandywine OP's sole cost and expense, the most recent Surveys
of the Property, which are in the possession of Brandywine OP. Such Surveys
shall have been prepared by a Surveyor(s) licensed to practice in the
Commonwealth of Virginia. During the Study Period, Prentiss shall have the right
to update such Surveys, at Prentiss' sole cost. On or before the Closing Date,
Prentiss shall cause the Title Company to furnish to Prentiss, at Brandywine
OP's sole cost and expense, (i) a title insurance commitment bearing an
effective date subsequent to the date of this Agreement issued by the Title
Company covering the Real Property, binding the Title Company to issue a ALTA
Form Owner's Policy of Title Insurance, showing title to be held currently by
the applicable Subsidiary Entities in a good, indefeasible and insurable
condition, together with

                                      -16-
<PAGE>

legible copies of all documents identified in such title insurance commitment as
exceptions to title certified as true and complete by the Title Company
(collectively, the "Title Commitment"), and (ii) reports of searches of the
Uniform Commercial Code records of both the county and State in which the
Property is located (collectively, the "UCC Reports") with respect to the state
of title to the Property and the Tysons Partnership Interest. Prior to the
expiration of the Study Period, Prentiss shall notify Brandywine OP of any
matters shown on the Survey or identified in the Title Commitment or the UCC
Reports that Prentiss is unwilling to accept (collectively, "Prentiss'
Objections"); however, Prentiss may not object to the Mass Mutual Loan
Documents. If any of Prentiss Objections consist of delinquent taxes, mortgages,
deeds of trust, security agreements, construction or mechanics' liens, tax liens
or other liens or charges in a fixed sum or capable of computation as a fixed
sum, then, to that extent, notwithstanding anything herein to the contrary,
Brandywine OP shall be obligated to cause Tysons Partnership and Subsidiary
Entities to pay and discharge (or bond against in a manner sufficient to cause
the Title Company to insure over such Prentiss Objections) any such Prentiss
Objections and Escrow Agent is authorized to pay and discharge at Closing such
Prentiss Objections to the extent not paid and discharged or bonded against at
Closing. Brandywine OP shall not be obligated to incur any expenses to cure any
Prentiss' Objections (including, without limitation, any lis pendens filed
against the Property) unless Brandywine OP agrees to cure such Prentiss'
Objections as hereinafter provided. Brandywine OP shall notify Prentiss on or
before the Closing Date whether Brandywine OP agrees to cure such Prentiss'
Objections. If Brandywine OP notifies Prentiss in writing on or before the
Closing Date that Brandywine OP agrees to cure such Prentiss' Objections,
Brandywine OP shall correct such Prentiss' Objections on or before the Closing
Date to the reasonable satisfaction of Prentiss. If Brandywine OP does not
notify Prentiss on or before the Closing Date of its agreement to cure such
Prentiss' Objections, Brandywine OP shall be deemed to have elected not to cure
such Prentiss' Objections, and Prentiss shall elect (1) to waive such Prentiss'
Objections or (2) to terminate this Agreement, in which case the Deposit shall
be promptly returned to Prentiss and the parties hereto shall be released from
all further obligations hereunder except those which expressly survive a
termination of this Agreement. Brandywine OP shall not, after the date of this
Agreement, subject the Property to or permit or suffer to exist any liens,
encumbrances, covenants, conditions, restrictions, easements or other title
matters or seek any zoning changes or take any other action which may affect or
modify the status of title without Prentiss' prior written consent. The Mass
Mutual Loan Documents and all title matters revealed by the Title Commitment,
UCC Reports and Survey and not objected to by Prentiss as provided above (other
than those rendering title defeasible and delinquent taxes, mortgages, deeds of
trust, security agreements and other liens and charges that are to be paid or
bonded against at Closing as provided above) shall be deemed Permitted Title
Exceptions. Notwithstanding the foregoing, Prentiss shall not be required to
accept contribution of the Tysons Partnership Interest if the Property is
subject to any matters which (i) may arise subsequent to the effective date of
the Title Commitment, UCC Reports and Survey examined by Prentiss during the
Study Period and (ii) impairs title to any portion of the Property and will not
be released or bonded against on or before the Closing Date. If a title
exception is disclosed by the Title Company which was not shown in the Title
Commitment or Survey and was not the result of Tysons Partnership's acts or
omission, then, unless Brandywine OP notifies Prentiss in writing by the Closing
Date that Brandywine OP

                                      -17-
<PAGE>

agrees to take such action as may be necessary to release such title exception
on or before the Closing Date, Prentiss may (i) terminate this Agreement by
written notice to Brandywine OP, in which event the Deposit shall be promptly
returned to Prentiss and the parties hereto shall be released from all further
obligations hereunder except those which expressly survive a termination of this
Agreement, or (ii) waive its objections to such title exception and consummate
the transactions contemplated herein.

                                  ARTICLE III
                 BRANDYWINE OP'S REPRESENTATIONS AND WARRANTIES

         To induce Prentiss to enter into this Agreement and to accept the
contribution of the Tysons Partnership Interest, Brandywine OP makes the
following representations and warranties with respect to the Property, upon each
of which Brandywine OP acknowledges and agrees that Prentiss is entitled to rely
and has relied:

         3.1. Organization and Power. Brandywine OP is a limited partnership,
duly formed, validly existing and in good standing under the laws of the State
of Delaware. Tysons Partnership is a general partnership duly formed and validly
existing under the laws of the State of Delaware. The Subsidiary Entities are
duly formed, validly existing and in good standing under the laws of the State
of Delaware. Each of Brandywine OP, Tysons Partnership and the Subsidiary
Entities is duly qualified to transact business in the Commonwealth of Virginia
and State of Delaware, and has all requisite powers and all material
governmental licenses, authorizations, consents and approvals to carry on its
respective business as now conducted and, as to Brandywine OP, to enter into and
perform its obligations hereunder and under any document or instrument required
to be executed and delivered on behalf of Brandywine OP hereunder.

         3.2. Authorization, Execution and Disclosure. This Agreement has been
duly authorized by all necessary action on the part of Brandywine OP, has been
duly executed and delivered by Brandywine OP, constitutes the valid and binding
agreement of Brandywine OP and is enforceable in accordance with its terms,
subject to the effect of applicable bankruptcy, insolvency, reorganization,
arrangement, moratorium or other similar laws affecting the rights of creditors
generally. Other than Brandywine OP, there is no other person or entity who has
an ownership interest in the Tysons Partnership Interest and other than Tysons
Partnership there is no person or entity who has an ownership interest in the
Subsidiary Entities or whose consent is required in connection with Brandywine
OP's performance of its obligations hereunder which has not been obtained,
except for FFI and Mass Mutual. The person executing this Agreement on behalf of
Brandywine OP has the authority to do so. Brandywine OP has not and will not
intentionally conceal, or cause Tysons Partnership, BRSCO or the Subsidiary
Entities to conceal, any information regarding the Tysons Partnership Interest,
the Property, the Tysons Partnership or either of the Subsidiary Entities.

         3.3. Non-contravention. The execution and delivery of, and the
performance by Brandywine OP of its obligations under, this Agreement do not and
will not (a) contravene, or

                                      -18-
<PAGE>

constitute a default under, any provision of (i) Brandywine OP's Organizational
Documents, the Original Tysons Partnership Agreement or the agreements of
limited partnership or limited liability company agreement, as applicable, of
the Subsidiary Entities, (ii) applicable law or regulation or any agreement,
judgment, injunction, order, decree or other instrument binding upon Brandywine
OP, Tysons Partnership or the Subsidiary Entities or to which the Property is
subject (except for the Mass Mutual Loan Documents), the result of which could
have a material adverse effect on the value of the Property or Brandywine OP's
ability to contribute the Tysons Partnership Interests to Prentiss and/or
Brandywine OP's ability to perform its obligations under this Agreement, or
(iii) result in the creation of any lien or other encumbrance on any asset of
Brandywine OP, Tysons Partnership or the Subsidiary Entities. Except as set
forth in the KPMG Lease identified on the Rent Roll or in the Original Tysons
Partnership Agreement there are no outstanding agreements (written or oral)
pursuant to which Brandywine OP, either directly or through Tysons Partnership,
BRSCO or the Subsidiary Entities, has agreed to sell or has granted an option or
right of first refusal to purchase the Tysons Partnership Interest, the Property
or the Subsidiary Entities or any interest therein or any part thereof.

         3.4. No Special Taxes. Brandywine OP has no knowledge of, nor has it
received any notice of, any special taxes or assessments relating to the
Property or any part thereof or any planned public improvements that may result
in a special tax or assessment against the Property.

         3.5. Compliance with Existing Laws and Restrictive Covenants. To
Brandywine OP's knowledge, Tysons Partnership possesses all Authorizations, each
of which is valid and in full force and effect, and no provision, condition or
limitation of any of the Authorizations has been breached or violated. Neither
Brandywine OP, nor to Brandywine OP's knowledge Tysons Partnership, BRSCO or any
of the Subsidiary Entities, has received any notice within the past three years,
of any existing or threatened violation of any provision of any (a) Applicable
Laws including, but not limited to, those of environmental agencies or insurance
boards of underwriters with respect to the ownership, operation, use,
maintenance or condition of the Property or any part thereof, or requiring any
repairs or alterations to the Property other than those that have been made
prior to the date hereof, and (b) restrictive covenants or deed restrictions
affecting the Property.

         3.6. Operating Agreements. There are no management, service, supply,
maintenance, employment or other contracts in effect with respect to Tysons
Partnership, the Subsidiary Entities or the Property of any nature whatsoever,
written or oral, other than the Management Agreement and the other Operating
Agreements listed on Schedule 3.6 hereof. To Brandywine OP's knowledge, Tysons
Partnership and the Subsidiary Entities have performed all of their respective
obligations under each of the Operating Agreements in all material respects and
no fact or circumstance has occurred which, by itself or with the passage of
time or the giving of notice or both, would constitute a default under any of
the Operating Agreements. To Brandywine OP's knowledge, all other parties to the
Operating Agreements have performed all of their obligations thereunder in all
material respects, and are not in default thereunder in any material respect.
Neither Brandywine OP, Tysons Partnership, BRSCO nor any of the

                                      -19-
<PAGE>

Subsidiary Entities has received any notice of any intention by any of the
parties to any of the Operating Agreements to cancel the same, nor has
Brandywine OP caused Tysons Partnership to cancel any of same. Brandywine OP
shall cause Tysons Partnership or the applicable Subsidiary Entity to terminate
any Operating Agreements which are terminable without penalty to be terminated
as of the Closing Date.

         3.7. Condemnation Proceedings; Roadways. Neither Brandywine OP, Tysons
Partnership nor any of the Subsidiary Entities has received any notice of any
condemnation or eminent domain proceeding pending or, to Brandywine OP's
knowledge, no such action is threatened, against the Property or any part
thereof. Brandywine OP has no knowledge of any change or proposed change in the
route, grade or width of, or otherwise affecting, any street, creek or road
adjacent to or serving the Property.

         3.8. Actions or Proceedings. There is no action, suit or proceeding
pending or known to Brandywine OP to be threatened against or affecting
Brandywine OP, Tysons Partnership or any of the Subsidiary Entities in any
court, before any arbitrator or before or by any Governmental Authority which
(a) in any manner raises any question affecting the validity or enforceability
of this Agreement or any other agreement or instrument to which Brandywine OP,
Tysons Partnership or any of the Subsidiary Entities is a party or by which it
is bound and that is or is to be used in connection with, or is contemplated by,
this Agreement, (b) is reasonably likely to materially and adversely affect the
business, financial position or results of operations of Brandywine OP, Tysons
Partnership, the Subsidiary Entities or the Property, (c) is reasonably likely
to materially and adversely affect the ability of Brandywine OP to perform its
obligations hereunder, or under any document to be delivered pursuant hereto or
the ability of Tysons Partnership or any of the Subsidiary Entities to own and
operate the Property, (d) is reasonably likely to create a lien on the Tysons
Partnership Interest, or the Property, or a Subsidiary Entity, any part thereof
or any interest therein or (e) is reasonably likely to otherwise materially and
adversely affect the Tysons Partnership Interest, a Subsidiary Entity or the
Property, any part thereof or any interest therein or the use, operation,
condition or occupancy thereof.

         3.9. Bankruptcy. No Act of Bankruptcy has occurred with respect to
Brandywine OP, Tysons Partnership or any of the Subsidiary Entities.

         3.10. Hazardous Substances. To Brandywine OP's knowledge, neither
Tysons Partnership, BRSCO, any of the Subsidiary Entities nor any previous
owner, tenant, occupant or user of the Property, nor any other person, has
engaged in or permitted any operations or activities upon, or any use or
occupancy of the Property or any portion thereof, for the purpose of or in any
way involving the handling, manufacture, treatment, storage, use, generation,
release, discharge, refining, dumping or disposal of any Hazardous Materials on,
under, in or about the Property in violation of any Applicable Laws. To
Brandywine OP's knowledge, no Hazardous Materials have migrated from or to the
Property upon, about, or beneath other properties in violation of any
Environmental Requirements. To Brandywine OP's knowledge, neither the Property
nor its existing or prior uses fail or failed to materially comply with
Environmental

                                      -20-
<PAGE>

Requirements. Brandywine OP has no knowledge of any permits, licenses or other
authorizations which are required under any Environmental Requirements with
regard to the current uses of the Property which have not been obtained and
complied with. To Brandywine OP's knowledge, neither Brandywine OP, Tyson
Partnership, BRSCO, any of the Subsidiary Entities nor any prior owner, occupant
or user of the Property has received any written notice concerning any alleged
violation of Environmental Requirements in connection with the Property or any
liability for Environmental Damages in connection with the Property for which
Brandywine OP, Tysons Partnership or a Subsidiary Entity (or Prentiss after
Closing) may be liable. To Brandywine OP's knowledge, no Hazardous Materials are
constructed, deposited, stored or otherwise located on, under, in or about the
Property in violation of any Environmental Requirements. To Brandywine OP's
knowledge, there exists no writ, injunction, decree, order or judgment
outstanding, nor any lawsuit, claim, proceeding, citation, summons or
investigation, pending or threatened, relating to any alleged violation of
Environmental Requirements on the Property, or from the suspected presence of
Hazardous Materials thereon, or relating to any Environmental Damages. To
Brandywine OP's knowledge, there are no underground or above ground chemical
treatment or storage tanks, or gas or oil wells are located on the Property. The
representations and warranties made by Brandywine OP in this Section 3.10 shall
be subject to the matters disclosed in the environmental reports delivered by
Brandywine OP to Prentiss pursuant to Section 2.4(b)(10) hereof.

         3.11. Parties in Possession. There are no parties in possession of the
Property except for tenants under written leases, copies of which will be
delivered to Prentiss pursuant to the terms hereof.

         3.12. Leases. There are no leases, concessions or occupancy agreements
in effect with respect to the Real Property other than the Leases listed on the
Rent Roll attached as Schedule 3.12; and Schedule 3.12 attached hereto is a
complete and correct list of all Leases in effect on the date of this Agreement.
Neither Brandywine OP, Tysons Partnership, BRSCO nor any of the Subsidiary
Entities has sent out any written notice of any default to any tenant under any
Lease which has not been cured except as set forth on Schedule 3.12. To
Brandywine OP's knowledge, the lessor has performed all obligations required of
it under all of the Leases and there remain no unfulfilled obligations of lessor
under the Leases, the nonperformance of which could entitle a tenant to damages
under such Lease or could cause lessor to be in default under such Lease. Except
as shown on Schedule 3.12, no tenant has given written notice to Brandywine OP,
Tysons Partnership, BRSCO or any of the Subsidiary Entities of its intention to
institute litigation with respect to any Lease that has not been dismissed, and
neither Brandywine OP, Tysons Partnership, BRSCO or any of the Subsidiary
Entities has been served with a citation notifying it of any litigation with
respect to any Lease that has not been dismissed. None of the Leases and none of
the rents or other amounts payable thereunder have been assigned, pledged or
encumbered except for any assignments, pledges or encumbrances which will be
fully released on or before the Closing Date and except pursuant to the Mass
Mutual Loan Documents. The Rent Roll is true, correct and complete in all
material respects as of the date shown in the Rent Roll and, to Brandywine OP's
knowledge, there has been no material adverse change with

                                      -21-
<PAGE>

respect to any of the items shown on the Rent Roll during the period from the
date thereof to the date of this Agreement, except as shown thereon.

         3.13. Leased Property. To Brandywine OP's knowledge, all leases of the
Leased Property, if any, are in good standing and free from default.

         3.14. Personal Property. Except for the security interests and liens
securing the Mass Mutual Loans, all of the Personal Property owned by the Tysons
Partnership or a Subsidiary Entity is free and clear of all liens and
encumbrances except for those which will be discharged by Tysons Partnership or
a Subsidiary Entity at Closing, and each of Tysons Partnership and the
Subsidiary Entities (if and to the extent it owns Personal Property) has good
and merchantable title thereto.

         3.15. Additional Representations and Warranties with Respect to the
Tysons Partnership Interest and Tysons Partnership.

                  (a) Each of the Original Tysons Partnership Agreement and the
limited partnership agreements and limited liability company agreement delivered
pursuant to Section 2.4(b)(19) is a true and correct copy of the partnership
agreement of Tysons Partnership, as amended through the date hereof. To
Brandywine OP's knowledge, the Original Tysons Partnership Agreement lists all
existing Partners (individually, a "Partner" and collectively, the "Partners")
of Tysons Partnership; and the Original Tysons Partnership Agreement accurately
describes the Tysons Partnership Interest. Brandywine OP is the sole owner of
the Tysons Partnership Interests, free and clear of all liens and encumbrances.
The Tysons Partnership Interests were not issued in violation of any federal or
state securities laws.

                  (b) Brandywine OP's tax basis in the Tysons Partnership as of
December 31, 2000 is $14,382,258. The remaining net Section 704(c) gain with
respect to the Tysons Partnership Interest as of December 31, 2000 is
$25,110,733.

                  (c) There are no equity, revenue, cash flow, profit or other
participations or similar rights which apply to Tysons Partnership or the
Subsidiary Entities except as set forth in the Original Tysons Partnership
Agreement or the agreements of limited partnership or limited liability company
agreement, as applicable, of the Subsidiary Entities.

                  (d) Except as provided in the Original Tysons Partnership
Agreement, there are no rights, subscriptions, options, rights of first refusal,
conversion rights or other agreements to purchase or to otherwise acquire any
securities or obligations of any kind convertible into any partnership interest
or other equity interests or participation interests in Tysons Partnerships or
any of the Subsidiary Entities.

                  (e) Neither Tysons Partnership nor any of the Subsidiary
Entities has engaged in any business other than the ownership, development,
leasing and management of the Property, has any subsidiaries other than the
Subsidiary Entities or has ever owned stock, shares or interests of any kind
whatsoever in any other entity.

                                      -22-
<PAGE>

         3.16. No Unpaid Charges. There are no unpaid charges, debts,
liabilities, claims or obligations arising from the construction, occupancy,
ownership, use or operation of the Property which could give rise to any
mechanic's or materialmen's or other statutory lien against the Property, or any
part thereof, or for which Tysons Partnership or the Subsidiary Entities will be
responsible or which will be due upon the initial occupancy of vacant space
(such as water or sewer connection or tap-in fee). The financial statements and
tax returns of Tysons Partnership delivered pursuant to Section 2.4(b) were
true, correct and complete in all material respects as of the respective dates
thereof.

         3.17. Condition of Improvements. Neither Brandywine OP, Tysons
Partnership, BRSCO nor any of the Subsidiary Entities, has received any written
notice, from any third party alleging that (a) any of the Improvements (i) are
defective in design or construction, (ii) are not in operating condition and a
satisfactory state of repair, or (iii) have roof leaks, (b) any mechanical
systems are not in reasonable working order and repair, or (c) Tysons
Partnership or any of the Subsidiary Entities has failed to operate the Property
in a commercially reasonable manner consistent with a modern office building;
provided, however, the foregoing representation and warranty as to notices
received shall not include any representation or warranty as to notices
concerning the aesthetic or other subjective quality of the design of the
Property or any system, element or component thereof and no representation or
warranty shall be deemed made as to any defect disclosed in any property
condition report obtained by Prentiss in connection with the Property.

         3.18. Access. Neither Brandywine OP, Tysons Partnership, BRSCO nor any
of the Subsidiary Entities, has any knowledge of any pending or threatened
governmental proceeding or any other fact or condition which would limit or
result in the termination of the Property's existing access to and from public
streets or roads.

         3.19. No Commitments. No commitments have been made to any Governmental
Authority, utility company, school board, church or other religious body, or any
homeowners' association or any other organization, group or individual, relating
to the Property which would impose an obligation upon Tysons Partnership or any
of the Subsidiary Entities to make any contribution or dedication of money or
land or to construct, install or maintain any improvements of a public or
private nature on or off the Property. Without limiting the generality of the
foregoing, neither Brandywine OP, Tysons Partnership, BRSCO nor any of the
Subsidiary Entities, is a party to any paving agreements or undertakings,
payback agreements, revenue bonds, utility debt service expenses or other
charges or expenses upon or relating to any of the Property or applicable
thereto.

         3.20. Not a "Foreign Person". Neither Brandywine OP, Tysons Partnership
nor any of the Subsidiary Entities is a "foreign person" within the meaning of
Section 1445 of the Internal Revenue Code, as amended (i.e., none of them is a
foreign corporation, foreign partnership, foreign trust, foreign estate or
foreign person as those terms are defined in the Internal Revenue Code and
regulations promulgated thereunder).

                                      -23-
<PAGE>

         3.21. Leasing Commissions. No brokerage or leasing commissions or other
fees or compensation are due or payable, or will become due and payable as a
result of agreements in place, to any person, firm, corporation or other entity
with respect to or on account of any of the Leases or any extension or renewals
thereof, except as set forth on the Schedule 3.21 hereof or Scheduled 6.4(g).

         3.22. Other Agreements. Except as set forth in the Original Tysons
Partnership Agreement and the Original Exchange Agreement, there are no options,
contracts or other obligations outstanding for the sale, exchange or transfer of
the Tysons Partnership Interest or any interest therein which would be superior
to the rights of Prentiss under this Agreement or which would survive Closing.

         3.23. Existing Secured Indebtedness. There is no debt secured by liens
on the Property, or any portion thereof, which will not be released and
discharged as of the Closing, other than the Mass Mutual Loans. None of the
borrowing parties is in default under the Mass Mutual Loan Documents, to
Brandywine OP's knowledge, no event has occurred which, with the passage of time
or the giving of notice, or both, would constitute a default thereunder, and
Exhibit D-2 is true, accurate and complete in all material respects.

         3.24. Employment on "At-Will" Basis. All persons and entities presently
employed in connection with the operation and maintenance of the Property are
employed on an "at will" basis, are dischargeable upon not more than thirty (30)
days' notice and, unless otherwise directed by Prentiss, shall be terminated by
Brandywine OP as of Closing. There are no labor disputes pending, nor to the
best of Brandywine OP's knowledge, contemplated pertaining to the operation or
maintenance of the Property, or any part thereof. Neither Brandywine OP, Tysons
Partnership nor any of the Subsidiary Entities has any employment agreements,
either written or oral, with any person which would require Prentiss, Tysons
Partnership or any of the Subsidiary Entities to employ any person after the
date hereof or the Closing Date.

         3.25. Additional Representations and Warranties with Respect to the
Issuance of Common Units and Preferred Units.

                  (a) Accredited Investor. Brandywine OP acknowledges and
understands that the issuance of the Common Units and the Special Units is
intended to be exempt from registration under the Securities Act, by virtue of
Section 4(2) and/or 4(6) of the Securities Act and Regulation D promulgated
thereunder ("Regulation D"), and, in accordance therewith and in furtherance
thereof, represents and warrants for the benefit of the Trust that it is an
"accredited investor" as that term is defined pursuant to Rule 501 of Regulation
D. Brandywine OP has no reason to expect that there will be any material adverse
change in its financial condition that would result in it no longer being an
accredited investor and will advise Prentiss of any such change occurring prior
to the issuance to Brandywine OP of the Common Units and the Special Units or
the Common Shares that may be issued upon redemption of the Common Units.

                                      -24-
<PAGE>

                  (b) Investment Experience. Brandywine OP has such knowledge
and experience in financial and business matters as is required for evaluating
the merits and risks of its acquisition of Common Units and Special Units, and
Brandywine OP or its representative has received such information requested by
it concerning the business, management and financial affairs of the Trust in
order to evaluate the merits and risks of making such acquisition.

                  (c) Acquisition Entirely for Own Account. Brandywine OP is
acquiring the Common Units and Special Units for its own account and for
investment purposes only and not with a present view to the resale or other
distribution of the Common Units or Special Units. Brandywine OP has no
agreement or understanding with any other person to grant a participation or
interest, of whatever nature, kind or description, in such Common Units and
Special Units.

                  (d) Bear Risk of Investment. Brandywine OP is able to bear the
substantial economic risks of an investment in the Common Units and Special
Units for an indefinite period of time, has no need for liquidity in such
investment, and can afford to lose its entire investment in the Option and the
Common Shares.

                  (e) Restrictions On Transfer. Notwithstanding anything herein
to the contrary, the Common Units and Special Units may not be resold in the
absence of registration of such Common Units and Special Units under the
Securities Act or an opinion of counsel reasonably satisfactory to the Trust
that such registration is not required. Any certificates representing the Common
Units, Special Units or Common Shares issuable upon redemption of the Common
Units shall bear a restricted stock legend indicating the foregoing restrictions
on transfer.

         3.26. LIMITATIONS ON REPRESENTATIONS AND WARRANTIES. PRENTISS HEREBY
AGREES AND ACKNOWLEDGES THAT, EXCEPT AS SET FORTH IN THIS ARTICLE III, OR AS
OTHERWISE EXPRESSLY STATED HEREIN OR IN ANY DOCUMENTS TO BE EXECUTED IN
CONNECTION HEREWITH, NEITHER BRANDYWINE OP NOR ANY AGENT, ATTORNEY, EMPLOYEE OR
REPRESENTATIVE OF BRANDYWINE OP HAS MADE ANY REPRESENTATION WHATSOEVER REGARDING
THE SUBJECT MATTER OF THIS AGREEMENT, OR ANY PART THEREOF, INCLUDING (WITHOUT
LIMITING THE GENERALITY OF THE FOREGOING) REPRESENTATIONS OR WARRANTIES AS TO
THE PHYSICAL NATURE OR CONDITION OF THE PROPERTY OR THE CAPABILITIES THEREOF,
AND THAT PRENTISS, IN EXECUTING, DELIVERING AND/OR PERFORMING THIS AGREEMENT,
DOES NOT RELY UPON ANY STATEMENT AND/OR INFORMATION TO WHOMEVER MADE OR GIVEN,
DIRECTLY OR INDIRECTLY, ORALLY OR IN WRITING, BY ANY INDIVIDUAL, FIRM OR
CORPORATION EXCEPT THOSE EXPRESSLY CONTAINED HEREIN OR DELIVERED PURSUANT
THERETO OR IN ANY DOCUMENTS EXECUTED IN CONNECTION HEREWITH. EXCEPT AS OTHERWISE
PROVIDED HEREIN, PRENTISS AGREES TO TAKE THE TYSONS PARTNERSHIP INTEREST AND ITS
INDIRECT INTEREST IN THE PROPERTY "AS IS," AS OF THE DATE HEREOF,

                                      -25-
<PAGE>

REASONABLE WEAR AND TEAR EXCEPTED. IN ADDITION, EXCEPT AS SET FORTH HEREIN,
BRANDYWINE OP MAKES NO REPRESENTATIONS OR WARRANTIES REGARDING THE COMPLIANCE
WITH ANY ENVIRONMENTAL REQUIREMENTS, INCLUDING THE EXISTENCE IN OR ON THE
PROPERTY OF HAZARDOUS MATERIALS. THE PROVISIONS OF THIS PARAGRAPH SHALL SURVIVE
THE CLOSING OR ANY TERMINATION HEREOF.

         Each of the representations and warranties contained in this Article
III and its various subparagraphs are intended for the benefit of Prentiss and
may be waived in whole or in part by Prentiss. All rights and remedies arising
in connection with the untruth or inaccuracy of any such representations and
warranties shall survive the Closing of the transaction contemplated hereby as
provided in Section 10.11 hereof, except to the extent that Brandywine OP gives
Prentiss written notice prior to Closing of the untruth or inaccuracy of any
representation or warranty, Prentiss otherwise obtains actual knowledge prior to
Closing of the untruth or inaccuracy of any representation or warranty, and
Prentiss nevertheless elects to close this transaction. Prentiss shall be deemed
to have actual knowledge of the untruth or inaccuracy of any representation or
warranty only if (i) Prentiss receives written notice from Brandywine OP
satisfying the foregoing requirements, or (ii) Thomas F. August, Robert K.
Wiberg, Michael Cooper or J. Kevan Dilbeck has actual knowledge of any such
untruth or inaccuracy. Except to the extent otherwise expressly provided in the
immediately preceding sentence, no investigation, audit, inspection, review or
the like conducted by or on behalf of Prentiss shall be deemed to terminate the
effect of any such representations, warranties and covenants, it being
understood that Prentiss has the right to rely thereon and that each such
representation and warranty constitutes a material inducement to Prentiss to
execute this Agreement and to close the transaction contemplated hereby and to
pay the Purchase Price to Brandywine OP.

         If any of Brandywine OP's representations and warranties made hereunder
are found by Prentiss to be incorrect prior to Closing to the extent they affect
the Tysons Partnership Interest, any of the Subsidiary Entities or the Property
or its operation in any material respect, Prentiss shall inform Brandywine OP in
writing and Prentiss' sole remedy, except as otherwise expressly provided in
clause (a)(ii) of the first sentence of Section 9.3 hereof or the last sentence
of Section 9.3 hereof, shall be termination of this Agreement on account thereof
and refund of the Deposit. If Prentiss elects not to so terminate this
Agreement, any remedy of Prentiss for breach of such warranties and
representations made prior to the Closing shall be deemed to be irrevocably
waived. Notwithstanding anything to the contrary contained in this Article, if
Brandywine OP breaches any representation or warranty made by Brandywine OP and
if prior to Closing Prentiss notifies Brandywine OP that it elects to terminate
this Agreement on account of such breach, Brandywine OP may by written notice to
Prentiss given or before the Closing Date agree to cure the breach (which breach
must be cured on or before the Closing Date), and Prentiss shall thereupon be
obligated to close the transaction and accept such cure as Prentiss' sole remedy
for such breach.

         The term "to Brandywine OP's knowledge" or similar phrase shall mean
the knowledge of Brandywine OP's chief executive officer, general counsel, chief
financial officer

                                      -26-
<PAGE>

and the current building engineer, property manager and leasing agent
(collectively, "Brandywine OP's Personnel with Knowledge") for the Property and
such inquiry shall include the direction by Brandywine OP to such persons to
review all files in their possession relating to the operation, ownership,
maintenance and management of the Property. Brandywine OP covenants that if
prior to Closing Brandywine OP obtains actual knowledge that any of the facts
represented and warranted by Brandywine OP under this Agreement are or become
untrue or inaccurate in any material respect, it will promptly inform Prentiss
in writing of its discovery.

         Brandywine OP's Personnel with Knowledge shall not have any personal
liability under this Agreement in their respective capacities as officers and/or
directors of Brandywine OP.

                                   ARTICLE IV
                    PRENTISS' REPRESENTATIONS AND WARRANTIES

         To induce Brandywine OP to enter into this Agreement and to contribute
the Tysons Partnership Interest and to accept the Common Units and the Special
Units, Prentiss hereby makes the following representations and warranties, upon
each of which Prentiss acknowledges and agrees that Brandywine OP is entitled to
rely and has relied:

         4.1. Organization and Power. Prentiss is a limited partnership, duly
formed, validly existing and in good standing under the laws of the State of
Delaware, and has all requisite partnership powers and all material governmental
licenses, authorizations, consents and approvals required to carry on its
businesses as now conducted and to enter into and perform its obligations under
this Agreement, including the issuance of the Common Units and Special Units,
and any document or instrument required to be executed and delivered on behalf
of Prentiss hereunder. Prentiss has the financial capability to acquire the
Tysons Partnership Interest pursuant to this Agreement.

         4.2. Non-contravention. The execution and delivery of this Agreement
and the performance by Prentiss of its obligations hereunder, including the
issuance of the Common Units and Special Units, do not and will not contravene,
or constitute a default under, any provisions of Prentiss' Organizational
Documents or applicable law or regulation, or any agreement, judgment,
injunction, order, decree or other instrument binding upon Prentiss.

         4.3. Litigation. There is no action, suit or proceeding, pending or
known to be threatened, against or affecting Prentiss or Prentiss in any court
or before any arbitrator or before any Governmental Authority which (a) in any
manner raises any question affecting the validity or enforceability of this
Agreement or any other agreement or instrument to which Prentiss is a party or
by which it is bound and that is to be used in connection with, or is
contemplated by, this Agreement, including the issuance of the Common Units and
Special Units, (b) could materially and adversely affect the business, financial
position or results of operations of Prentiss, or (c) could materially and
adversely affect the ability of Prentiss to perform its obligations hereunder,
or under any document to be delivered pursuant hereto.

                                      -27-
<PAGE>

         4.4. Bankruptcy. No Act of Bankruptcy has occurred with respect to
Prentiss.

         4.5. Authorization, Execution and Disclosure. This Agreement and the
performance of Prentiss of its obligations hereunder, including the issuance of
the Common Units and the Special Units, have been duly authorized by all
necessary action on the part of Prentiss, and this Agreement has been duly
executed and delivered by Prentiss, constitutes the valid and binding agreement
of Prentiss and is enforceable in accordance with its terms, subject to the
effect of applicable bankruptcy, insolvency, reorganization, arrangement,
moratorium or other similar laws affecting the rights of creditors generally.

         4.6. The Common Units.

                  (a) The Common Units, when issued by Prentiss on the Closing
Date, will be redeemable, subject to the terms and conditions set forth in the
Prentiss Partnership Agreement, including the Fourteenth Amendment thereto, for
an equal number of Common Shares. Each Common Unit will be entitled to receive a
distribution from the Trust at such time and in such amount as the holder of a
Common Share is entitled to receive a distribution on such Common Share from the
Trust, pro rated pursuant to Section 2.1(a)(ii). Any Common Shares issuable upon
redemption of the Common Units, upon issuance: (i) will be duly and validly
issued, fully-paid and non-assessable and (ii) will be approved for listing with
the NYSE under the Securities Act. Prentiss will cause the Trust to file with
the Securities and Exchange Commission a registration statement covering the
resale of any such Common Shares and to use its best efforts to have such
registration statement declared effective under the Securities Act, all in
accordance with and as provided in Section 8.06 of the Prentiss Partnership
Agreement and to maintain the effectiveness of such registration statement until
the earlier of six months from the date of redemption and the date such Common
Shares are resold.

                  (b) The Trust meets the requirements for qualification as a
real estate investment trust under Sections 856 through 860 of the Internal
Revenue Code and the rules and regulations thereunder as currently in effect.

         4.7. Allocation Methodology. Prentiss represents and warrants that
throughout Brandywine OP's ownership of the Special Units, and notwithstanding
anything to the contrary in any amendments to the Prentiss Partnership
Agreement, Brandywine OP will receive annually an allocation of net income of
Prentiss and not an allocation of gross income of Prentiss. For purposes of this
Section 4.7, net income amounts are defined under Section 703 of the Internal
Revenue Code of 1986, as amended. Additionally, for purposes of this Section
4.7, gross income amounts are defined as an item of Prentiss' gross receipts.

                                   ARTICLE V
                              CONDITIONS PRECEDENT

         5.1. As to Prentiss' Obligations. Prentiss' obligations hereunder are
subject to the satisfaction of the following conditions precedent:

                                      -28-
<PAGE>

                  (a) Brandywine OP's Deliveries. Brandywine OP shall have
delivered to or for the benefit of Prentiss, on or before the Closing Date, all
of the documents and other information required of Brandywine OP pursuant to
Sections 7.2 and 7.4 hereof.

                  (b) Representations, Warranties and Covenants; Obligations of
Brandywine OP; Certificate. All of Brandywine OP's representations and
warranties made in this Agreement shall be true and correct in all material
respects as of the date hereof and as of the date of Closing as if then made;
Brandywine OP shall have performed in all material respects all of its covenants
and other obligations under this Agreement; and Brandywine OP shall have
executed and delivered to Prentiss at Closing a certificate to the foregoing
effect.

                  (c) Title Insurance. Good and indefeasible fee simple title to
the Property by the applicable Subsidiary Entity shall be insurable as such by
the Title Company, subject only to Permitted Title Exceptions as determined in
accordance with Section 2.4 hereof and including, without limitation, all
applicable deletions of standard exceptions and endorsements permitted under
applicable state law which are customarily required by institutional investors
purchasing property comparable to the Property, including a non-imputation
endorsement.

                  (d) Condition of Improvements. The Improvements (including but
not limited to the mechanical systems, plumbing, electrical, wiring, fixtures,
heating, air conditioning and ventilating equipment, elevators, boilers,
equipment, roofs, structural members and furnaces) shall be in the same
condition at Closing as they are as of the date hereof, reasonable wear and tear
excepted. Brandywine OP shall not have removed or caused or permitted to be
removed any part or portion of the Property without Prentiss' prior written
consent unless the same is replaced, prior to Closing, with a similar item of at
least equal suitability, quality and value, free and clear of any lien or
security interest.

                  (e) Utilities. All of the Utilities shall be installed in and
operating at the Property, and service shall be available for the removal of
garbage and other waste from the Property.

                  (f) Due Diligence Materials. All rent rolls, lists, schedules
and other documents furnished by Brandywine OP to Prentiss under this Agreement
shall be true and correct in all material respects, except for inaccuracies as
to which Prentiss was given written notice by Brandywine OP or otherwise had
actual knowledge prior to the end of the Study Period.

                  (g) No Additional Proceedings; Tenant Defaults. Except for
matters as to which Prentiss was given written notice by Brandywine OP or
otherwise had actual knowledge prior to the end of the Study Period, on the
Closing Date, there shall be no (a) litigation pending or threatened, seeking
(i) to enjoin the consummation of the transactions contemplated hereunder, (ii)
to recover title to the Property, or any part thereof or any interest therein,
(iii) to increase substantially ad valorem taxes theretofore assessed against
any of the

                                      -29-
<PAGE>

Property, (iv) to enjoin the violation of any law, rule, regulation, restrictive
covenant or zoning ordinance that may be applicable to the Property, or (v)
claiming defaults or other liability of lessor under Leases by tenants leasing
five percent (5%) or more of the rentable square feet of the Improvements, in
the aggregate or (b) monetary default in excess of thirty (30) days for which a
written notice of default has been given to a tenant and which constitutes an
event of default under, and as defined in, the applicable Lease, other material
default or any threatened or reasonably anticipated material default by tenants
leasing five percent (5%) or more of the rentable square feet of the
Improvements, in the aggregate.

                  (h) Estoppel Letters. The estoppel letters to be delivered at
Closing pursuant to Section 7.2(g) hereof shall have been obtained and delivered
and shall reflect no facts at material variance with the facts disclosed on the
Rent Roll and records provided to Prentiss during the Study Period.

                  (i) Mass Mutual Consent. Mass Mutual shall have executed and
delivered the Mass Mutual Consent in substantially the form of Exhibit D-1
hereto. In the event that Mass Mutual shall charge any fees or expenses in
connection with giving its consent, Brandywine OP shall be responsible for the
payment of such fees and expenses.

                  (j) FFI Consent. FFI shall have executed and delivered the FFI
Consent in substantially the form of Exhibit B hereto.

                  (k) Termination Agreement. FFI shall have executed and
delivered the Termination Agreement in substantially the form of Exhibit I
hereto.

                  (l) Replacement True Up. FFI shall have terminated the
Original True Up and shall have executed the Replacement True Up.

Each of the conditions contained in this Section 5.1 are intended for the
benefit of Prentiss and may be waived in whole or in part, by Prentiss, but only
by an instrument in writing signed by Prentiss.

         5.2. As to Brandywine OP's Obligations. Brandywine OP's obligations
hereunder are subject to the satisfaction of the following conditions precedent:

                  (a) Prentiss' Deliveries. Prentiss shall have delivered to or
for the benefit of Brandywine OP, on or before the Closing Date, all of the
documents and payments required of Prentiss pursuant to Sections 7.3 and 7.4
hereof.

                  (b) Representations, Warranties and Covenants; Obligations of
Prentiss. All of Prentiss' representations and warranties made in this Agreement
shall be true and correct in all material respects as of the date hereof and as
of the date of Closing as if then made and Prentiss shall have performed in all
material respects all of its covenants and other obligations under this
Agreement.

                                      -30-
<PAGE>

                  (c) Mass Mutual Consent. Mass Mutual shall have executed and
delivered the Mass Mutual Consent in substantially the form of Exhibit D-1
hereto.

                  (d) FFI Consent. FFI shall have executed and delivered the FFI
Consent in substantially the form of Exhibit B hereto.

                  (e) Termination Agreement. FFI shall have executed and
delivered the Termination Agreement in substantially the form of Exhibit I
hereto.

                  (f) Replacement True Up. FFI shall have terminated the
Original True Up and Prentiss and FFI shall have executed the Replacement True
Up.

Each of the conditions contained in this Section is intended for the benefit of
Brandywine OP and may be waived in whole or in part, by Brandywine OP, but only
by an instrument in writing signed by Brandywine OP.

                                   ARTICLE VI
                           COVENANTS OF BRANDYWINE OP

         To induce Prentiss to enter into this Agreement and to accept the
contribution of the Tysons Partnership Interest, and to issue the Common Units
and Special Units, Brandywine OP covenants and agrees to the following:

         6.1. Operating Agreements. Brandywine OP shall not permit, prior to the
Closing, Tysons Partnership or any of the Subsidiary Entities to enter into any
new management agreement, maintenance or repair contract, supply contract, lease
in which it is lessee or other agreements with respect to the Property which
cannot be terminated on or before the Closing Date, nor shall Brandywine OP,
Tysons Partnership, BRSCO or any of the Subsidiary Entities enter into any
agreements modifying the Operating Agreements in any material respect, unless
(a) any such agreement or modification will not bind Prentiss, Tysons
Partnership or any of the Subsidiary Entities or the Property after the date of
Closing or (b) Brandywine OP has obtained Prentiss' prior written consent to
such agreement or modification. Brandywine OP agrees to cause to be cancelled
and terminated effective as of the Closing Date any Operating Agreements (except
for the Management Agreement, which is to be assigned to Manager) which are
either with an affiliate of Brandywine OP or terminable without substantial
penalty.

         6.2. Warranties and Guaranties. Brandywine OP shall not, prior to the
Closing, permit Tysons Partnership, BRSCO or any of the Subsidiary Entities to
release or modify any Warranties and Guaranties, if any, except with the prior
written consent of Prentiss.

         6.3. Insurance. Prior to the Closing Date, Brandywine OP shall cause
Tysons Partnership or the Subsidiary Entities to pay all premiums on, and
neither Tysons Partnership nor the Subsidiary Entities shall cancel or
voluntarily allow to expire, any of the Insurance Policies unless such policy is
replaced, without any lapse of coverage, by another policy or policies providing
coverage at least as extensive as the policy or policies being replaced.
Brandywine OP

                                      -31-
<PAGE>

hereby indemnifies and holds Prentiss harmless from and against all losses,
costs, damages and expenses resulting from actions involving bodily or personal
injury or property damage in or about any of the Property that occurred prior to
the Closing Date, regardless of when the claim was made, but only to the extent
coverage under the applicable Insurance Policy or Policies is not sufficient and
paid, and this indemnity shall survive the Closing Date.

         6.4. Operation of Property Prior to Closing. Brandywine OP and Prentiss
represent, warrant, covenant and agree with Prentiss that, between the date of
this Agreement and the date of Closing (but in any event subject to Brandywine
OP's obligations to comply with its fiduciary duties under the Original Tysons
Partnership Agreement):

                  (a) Subject to the restrictions contained herein, Brandywine
OP shall cause Tysons Partnership and the Subsidiary Entities to operate the
Property in the same manner in which Tysons Partnership and the Subsidiary
Entities operated the Property prior to the execution of this Agreement, so as
to keep the Property in good condition, reasonable wear and tear excepted.

                  (b) Brandywine OP shall maintain the books of account and
records of Tysons Partnership and the Subsidiary Entities in the usual, regular
and ordinary manner, in accordance with sound accounting principles applied on a
basis consistent with the basis used in keeping such books in prior years.

                  (c) Brandywine OP shall cause Tysons Partnership and the
Subsidiary Entities to maintain in full force and effect all Insurance Policies.

                  (d) Brandywine OP shall cause Tysons Partnership and the
Subsidiary Entities to punctually perform and discharge all obligations and
undertakings of Tysons Partnership and the Subsidiary Entities under the Leases
and shall not permit a default by lessor to occur thereunder.

                  (e) Brandywine OP shall cause Tysons Partnership and the
Subsidiary Entities to use and operate the Property in compliance with
Applicable Laws and the requirements of the Mass Mutual Loan Documents and any
Lease, Operating Agreement and Insurance Policy affecting the Property.

                  (f) Brandywine OP shall cause Tysons Partnership and the
Subsidiary Entities to pay prior to delinquency all ad valorem and other taxes
due and payable with respect to the Property or its operation.

                  (g) Without the express prior written consent of Prentiss
(which consent shall not be unreasonably withheld and shall be deemed to have
been given if Prentiss fails to respond to a written request from Brandywine OP
for such consent within two (2) business days following Prentiss' receipt of any
such request), Brandywine OP shall not permit Tysons Partnership and/or the
Subsidiary Entities to: (i) enter into new Leases of any kind or nature
affecting the Property; or (ii) grant a renewal or extension of any existing
Lease, or

                                      -32-
<PAGE>

consent to any assignment, sublease or expansion of any existing lease or
portion thereof which, by the terms of any such Lease, requires lessor's prior
consent as a condition to any such renewal, extension, assignment, sublease or
expansion. Brandywine OP shall not, without the express written consent of
Prentiss, in any manner permit Tysons Partnership and the Subsidiary Entities to
change, modify, extend, renew or terminate any Lease except as required by the
terms thereof, or waive in any material respect any of the tenant's obligations
under any Lease; provided, Leases with Brandywine OP's management company may be
terminated on or before the Closing Date without the prior consent of Prentiss.
Neither Brandywine OP, Tysons Partnership nor any of the Subsidiary Entities
shall apply all or any part of the security or damage deposit of a tenant under
any Lease to obligations of such tenant, unless such tenant has vacated its
portion of the Property as of the Closing Date. Notwithstanding the foregoing,
Prentiss hereby approves the new Leases which have been entered into by Tysons
Partnership and the Subsidiary Entities and costs associated therewith, as more
particularly described in Schedule 6.4(g) hereto.

                  (h) Brandywine OP shall cause all debts and liabilities for
labor, materials, services and equipment incurred in the construction, operation
and development of the Property, including leasehold improvements, to be
promptly paid by Tysons Partnership and the Subsidiary Entities.

                  (i) Neither Brandywine OP, Tysons Partnership, BRSCO nor any
of the Subsidiary Entities shall (1) make any agreements which shall be binding
upon Prentiss, Tysons Partnership or any of the Subsidiary Entities with respect
to the Property, or (2) reduce, or cause to be reduced any rents or any other
revenues over which Tysons Partnership or BRSCO has operational control.

                  (j) Brandywine OP shall promptly deliver to Prentiss upon
Prentiss' request such reports showing the revenue and expenses of the Property,
Tysons Partnership and the Subsidiary Entities as Brandywine OP customarily
keeps or receives internally for its own use.

                  (k) Except as required by the terms thereof or hereof,
Brandywine OP shall not in any manner permit Tysons Partnership, BRSCO or any of
the Subsidiary Entities to change, modify, extend, renew or terminate any
Operating Agreement which would be binding on Prentiss, Tysons Partnership or
either Subsidiary Entity or the Property without the express written consent of
Prentiss.

                  (l) Brandywine OP shall promptly advise Prentiss of any
litigation, arbitration or administrative hearing concerning or affecting the
Property, Tysons Partnership or the Subsidiary Entities of which Brandywine OP
obtains actual knowledge.

                  (m) Brandywine OP shall cause Tysons Partnership and the
Subsidiary Entities to keep the Mass Mutual Loans current, to comply with the
terms and provisions of the Mass Mutual Loan Documents and to immediately send
Prentiss copies of all correspondence

                                      -33-
<PAGE>

received from Mass Mutual. Neither Brandywine OP, Tysons Partnership nor the
Subsidiary Entities shall modify any provisions of the Mass Mutual Loan
Documents except for their joinder in the Mass Mutual Consent.

         6.5. No Marketing. Brandywine OP shall not cause Tysons Partnership or
any of the Subsidiary Entities to market the Property for sale or enter into
discussions or negotiations with potential purchasers of the Property unless
this Agreement has been terminated pursuant to its terms.

         The foregoing covenants of Brandywine OP are for the benefit of
Prentiss or its assignee of its rights under this Agreement.

                                  ARTICLE VII
                                     CLOSING

         7.1. Closing. The Closing shall occur within five (5) days after the
conditions precedent set forth in Sections 5.1 and 5.2 have been satisfied. As
more particularly described below, at the Closing the parties hereto will meet
to (i) execute all of the documents required to be delivered in connection with
the transactions contemplated hereby (the "Closing Documents"), (ii) deliver the
same to Escrow Agent, and (iii) take all other action required to be taken in
respect of the transactions contemplated hereby. The Closing will occur at the
offices of the Escrow Agent. At the Closing, the Title Company shall update the
title to the Property and, provided there has been no change in the status of
title as reflected in the Title Commitment and Survey which has not been waived
by Prentiss pursuant to Section 2.4(c) hereof, and Escrow Agent shall record,
release and date, where appropriate, the Closing Documents in accordance with
the joint instructions of Brandywine OP and Prentiss and shall send, by wire
transfer, all sums, if any, owing to Brandywine OP or Prentiss hereunder to
Brandywine OP or Prentiss, as applicable. As provided herein, the parties hereto
will agree upon adjustments and prorations to certain items which cannot be
exactly determined at the Closing and will make the appropriate adjustments with
respect thereto. Possession of the Property (as the new Managing Partner of
Tysons Partnership) shall be delivered to Prentiss on the Closing Date, subject
only to Permitted Title Exceptions and the rights of tenants under the Leases.
Notwithstanding anything herein to the contrary, if the Closing Date does not
occur by April 30, 2001, and the provisions of Section 9.3 or 9.5 are not
applicable, then either party may terminate this Agreement by notice to the
other party hereto, in which event neither party shall have any further
obligation to the other except for the indemnities and other provisions of this
Agreement which expressly survive a termination of this Agreement, and the
Deposit, less the Independent Consideration, shall be promptly refunded to
Prentiss.

         7.2. Brandywine OP's Deliveries. At the Closing, Brandywine OP shall
deliver to Escrow Agent all of the following instruments, each of which shall
have been duly executed and shall be dated as of the Closing Date:

                  (a) The certificate required by Section 5.1(b) hereof.

                                      -34-
<PAGE>

                  (b) The Partnership Assignment and Assumption Agreement.

                  (c) The Management Agreement Assignment and Assumption
Agreement (executed by BRSCO).

                  (d) The Termination Agreement executed by Brandywine OP and
Baita.

                  (e) The Mass Mutual Consent.

                  (f) The Amended and Restated Tysons Partnership Agreement
executed by Baita, together with an amended name change certificate.

                  (g) An updated certified Rent Roll dated as of the date
preceding the Closing Date.

                  (h) Either (i) an estoppel letter in the form of Exhibit K
hereto dated not more than thirty (30) days prior to the Closing Date (a) from
each of the tenants under the Leases covering 7,500 square feet or more, and (b)
from tenants leasing, in the aggregate, at least seventy-five percent (75%) of
the remainder of the Improvements, or (ii) an estoppel letter executed by
Brandywine OP certifying to the matters specified in Exhibit K hereto for any
tenant which does not execute an estoppel letter. Any estoppel letter provided
by Brandywine OP for a Lease pursuant to clause (ii) above shall state that
Brandywine OP shall have no liability thereunder if Brandywine OP subsequently
provides to Prentiss an estoppel letter in the form of Exhibit K from the tenant
under such Lease.

                  (i) Such agreements, affidavits or other documents as may be
required by the Title Company to issue the Owner's Title Policy (and a lender's
policy for the benefit of Mass Mutual) subject only to Permitted Title
Exceptions and to issue a non-imputation endorsement and the endorsements
thereto which are customarily required by institutional investors assuming notes
and mortgages encumbering property comparable to the Property.

                  (j) An updated Title Commitment issued by the Title Company,
dated as of the date and time of Closing, subject only to the Permitted Title
Exceptions.

                  (k) All original Warranties and Guaranties in Brandywine OP's
possession or reasonably available to Brandywine OP.

                  (l) To the extent in Brandywine OP's possession or reasonably
available to Brandywine OP, a valid, final and unconditional certificate of
occupancy for the Real Property and Improvements, issued by the appropriate
Governmental Authority and, if required by Applicable Laws, transferred to
Prentiss.

                  (m) The originals of any Operating Agreements which are to
remain in place.

                                      -35-
<PAGE>

                  (n) Executed originals of all Leases, leases of Leased
Property, permits and, to the extent in Brandywine OP's possession or control,
Authorizations as required hereunder and any other documents or instruments
affecting the Property or the ownership and operation thereof.

                  (o) All current real estate and personal property tax bills in
Brandywine OP's possession or under its control.

                  (p) All books, records, operating reports, appraisal reports,
files and other materials in Brandywine OP's possession or control which are
necessary in Prentiss' reasonable discretion to maintain continuity of operation
of the Property. Prentiss covenants to permit Brandywine OP to photocopy any of
the matters described in this Subparagraph 7.2(p) for a period of three (3)
years following the Closing Date, which covenant of Prentiss shall survive for
such three (3) year period.

                  (q) Written notice executed by Brandywine OP notifying all
interested parties, including, without limitation, all tenants under any Leases,
that Prentiss has replaced Brandywine OP as the Managing Partner of the Tysons
Partnership and Manager as the manager or the Property and directing that all
payments, inquiries and the like to Tysons Partnership be forwarded to Manager
at the address to be provided by Prentiss (or as otherwise directed by
Prentiss).

                  (r) A current UCC Report showing no financing statements by
Brandywine OP as Debtor covering the Tysons Partnership Interest.

                  (s) All keys to all locks on the Property in the possession of
Brandywine OP, together with an accounting for such keys in the possession of
others.

                  (t) Possession of the Property (as Managing Partner of Tysons
Partnership) subject only to the Permitted Encumbrances.

                  (u) Certified copies of a incumbency certificate and
resolutions authorizing the execution by Brandywine OP of this Agreement and all
documents to be executed by Brandywine OP on the Closing Date.

                  (v) Estoppel letters from each owners association created
pursuant to restrictive covenants or deed restrictions affecting the Property
certifying that (i) the Property complies with such restrictive covenants or
deed restrictions, and (ii) no assessments are due and owing with respect to the
Property.

                  (w) The FIRPTA Certificate.

                  (x) Certificates of Subsistence for each of the Subsidiary
Entities.

                                      -36-
<PAGE>

                  (y) Estoppel letters from each owners association created
pursuant to restrictive covenants or deed restrictions affecting the Real
Property certifying that (i) the Real Property complies with such restrictive
covenants or deed restrictions, and (ii) no assessments are due and owing with
respect to the Real Property, and estoppel letters from adjoining property
owners who are parties to adjoining landowner agreements binding on any portion
of the Real Property; provided, Brandywine OP may execute an estoppel letter
certifying to the foregoing matters for an owners association or property owner
that does not execute any such estoppel letter, which estoppel letter shall
continue in effect unless and until the applicable estoppel letter is
subsequently provided from any such owners association or property owner.

                  (z) Any other document or instrument reasonably requested by
Prentiss in connection with the transactions contemplated hereby.

                  (aa) Brandywine OP confirms that it shall retain and remove
all Leased Property from the Property and that Prentiss shall not be responsible
after Closing for any costs or lease obligations related to such Leased
Property.

         7.3. Prentiss' Deliveries. At the Closing Prentiss shall deliver to the
Escrow Agent all of the following instruments, each of which shall have been
duly executed and shall be dated as of the Closing Date.

                  (a) The Partnership Assignment and Assumption Agreement.

                  (b) The Management Agreement Assignment and Assumption
Agreement.

                  (c) The executed Fourteenth Amendment.

                  (d) A certificate representing the Special Units.

                  (e) The Amended and Restated Tysons Partnership Agreement,
together with an amended name change certificate.

                  (f) The Replacement Exchange Agreement.

                  (g) The Replacement Registration Rights Agreement.

                  (h) The Substitute Non-Recourse Guaranty.

                  (i) The Mass Mutual Consent.

                  (j) Any other document or instrument reasonably requested by
Brandywine OP in connection with the transactions contemplated hereby.

                                      -37-
<PAGE>

         7.4. Mutual Deliveries. At the Closing, Prentiss and Brandywine OP
shall mutually execute and deliver each to the other:

                  (a) A final closing statement reflecting the adjustments and
prorations required hereunder and the allocation of income and expenses required
hereby.

                  (b) Such other and further documents, papers and instruments
as may be reasonably required by the parties hereto in connection with the
transactions contemplated hereby or their respective counsel.

                  (c) A Statement of Partnership Authority (or similar document)
to be filed with the State Corporation Commission of the Commonwealth of
Virginia showing Prentiss as a general partner in Tysons Partnership and the
withdrawal of Brandywine OP as a general partner in Tysons Partnership.

         7.5. Closing Costs. Except as is explicitly provided in this Agreement,
each party hereto shall pay its own legal fees and expenses. Brandywine OP shall
pay for the costs associated with obtaining the FFI Consent and Mass Mutual
Consent. Brandywine OP shall pay all costs for title searches, tax certificates
and all premiums for the issuance of the Title Policy described in Section
7.2(i); all costs of providing the matters described in Sections 2.4(b) and (d)
to Prentiss; and one-half (1/2) of any escrow fees or similar charges of the
Escrow Agent. Prentiss shall pay one-half (1/2) of any escrow fees or similar
charges of the Escrow Agent. Brandywine OP shall pay all debt transfer and
similar fees associated with the Mass Mutual Loans. Transfer taxes and
documentary transfer stamps, if any, shall be paid in accordance with the local
customs in the States in which the Property is located. All other expenses
incurred by Brandywine OP or Prentiss with respect to the Closing shall be borne
and paid for exclusively by the party incurring same, without reimbursement,
except to the extent otherwise specifically provided herein.

         7.6. Miscellaneous Payments and Revenue and Expense Allocations.

                  (a) Pursuant to the Partnership Assignment and Assumption
Agreement, at the Closing, Brandywine OP shall assign to Prentiss, as part of
its contribution of the Tysons Partnership Interest, all of its right, title and
interest in and to the Additional Special Distribution. In addition, at or prior
to the Closing, Brandywine OP shall request Tysons Partnership to repay to FFI
the entire accrued but unpaid Priority Return (as defined in the Original Tysons
Partnership Agreement) as of December 31, 2000 (i) by applying on account
thereof $500,000 in the "Cash Shortfall Account" maintained by Tysons
Partnership with First Union National Bank ("First Union") and (ii) by applying
on account of the balance thereof a portion of the cash held in the "Equity
Retainer Buy-Out Account" maintained by Tysons Partnership with First Union
(with the result that the Additional Special Distribution thereafter payable by
Tysons Partnership to Prentiss shall be reduced by the dollar amount so applied
pursuant to the preceding clause (ii)).

                                      -38-
<PAGE>

                  (b) Brandywine OP agrees that Tysons Partnership will use the
balance that remains in the Cash Shortfall Account after application of $500,000
therein to fund the distribution to FFI referred to in Section 7.6(a) above to
pay costs of the current lobby renovation at 8260 Greensboro.

                  (c) Brandywine OP agrees to make quarterly payments to
Prentiss on each April 15, July 15, October 15 and January 15, commencing July
15, 2001 in an amount, not to exceed $200,000 per quarter, equal to the excess
of (i) the accrued but unpaid Subordinated Priority Return (as defined in the
Original Tysons Partnership Agreement and being an annual amount equal to
$1,120,000 for each of calendar years 2001 through 2004 and $1,200,000 for
calendar years thereafter) accruing from and after the Closing Date over (ii)
the cumulative distributions made by Tysons Partnership to Prentiss from and
after the Closing Date; provided that Brandywine's aggregate payment obligations
under this Section 7.6(c) shall, in no event, exceed $2,400,000 and shall not
relate to any calendar year after 2010 (that is, the agreement to make payments
on account of any such excess shall terminate entirely on January 15, 2011). For
purposes of computing the quarterly payment obligation, if any, of Brandywine OP
(i) the Subordinated Priority Return shall be deemed due and payable by Tysons
Partnership on the fifteenth day of each April, July, October and January, (ii)
any Net Cash Flow which, in the reasonable good faith judgment of Prentiss, is
available for distribution to it on account of the Subordinated Priority Return
but which is not in fact distributed to it shall be deemed to have been
distributed to it and (iii) any accrued but unpaid Subordinated Priority Return
shall not accrue interest.

                  (d) Brandywine OP shall deposit with Escrow Agent the sum of
$150,000 (the "Netplex Escrow") at Closing, such sum to be used for the specific
purpose set forth in this Section 7.6 (d). Until such time as Prentiss has
leased to a tenant and such tenant under such lease is required to pay rent for
all or a material portion of that certain suite of approximately 10,350 square
feet currently occupied by Netplex at 8260 Greensboro, Prentiss shall be
permitted to draw an amount not to exceed $25,000 per month from the Netplex
Escrow on the 30th day of each month. Once a tenant is required to pay rent
under the lease for the aforesaid space, Prentiss' right to draw funds under the
Netplex Escrow shall cease and all remaining funds, if any, in such escrow shall
be wire transferred to Brandywine OP. Prentiss covenants and agrees: (i) to use
its commercially reasonable efforts to lease such space and (ii) not to permit
any lease for the aforesaid space to include a "free rent" or "rental abatement"
provision which relates to the first six months (or any portion thereof) of the
term.

                  (e) Prentiss agrees that in connection with the assignment of
the Management Agreement by BRSCO to Manager at Closing, BRSCO shall be entitled
to: (i) all Management Fees accrued under Section 14 of the Management Agreement
based on Gross Receipts (as defined in the Management Agreement) attributable to
the Property and accrued to the Closing Date; (ii) all leasing commissions
payable under Section 15 of the Management Agreement for leases executed for
space at the Property prior to the Closing Date; (iii) the construction
management fee payable under Section 16 of the Management Agreement for
additions or capital improvements committed to be made by Tysons Partnership, a
Subsidiary

                                      -39-
<PAGE>

Entity or Brandywine OP, on behalf of Tysons Partnership or a Subsidiary Entity,
prior to the Closing Date; and (iv) reimbursement on account of payroll expenses
associated with management of the Property to the Closing Date.

                  (f) Prentiss agrees that Brandywine OP shall be entitled to
accrued interest through the Closing Date on the unused capital attributable to
the Additional Special Distribution which, but for the contribution by
Brandywine OP to Prentiss of the Tysons Partnership Interest, would be payable
to Brandywine OP under the last paragraph of Section 11.1 of the Original Tysons
Partnership Agreement (such unused capital being held in an escrow account with
First Union National Bank). Brandywine OP confirms that the accrued interest
will be paid to it by the Tysons Partnership at or prior to Closing.

                  (g) Prentiss agrees that at such time as it has received
payment in full of the Subordinated Priority Return from Net Cash Flow (as
defined in the Original Tysons Partnership Agreement) then, to the extent it
thereafter receives a distribution from Tysons Partnership of Net Cash Flow,
Prentiss shall remit to Brandywine OP up to $345,726, of such Net Cash Flow, but
in no event shall Prentiss make any such payment prior to January 5, 2004. For
clarity, payments by Brandywine OP under Section 7.6(c) shall not be deemed to
be payments that reduce the Subordinated Priority Return.

                  (h) Schedule 6.4(g) identifies refurbishment allowances,
tenants improvement costs and leasing commissions (collectively, "Leasing
Costs") with respect to the Leases executed with Prentiss' consent after January
1, 2001 and all historic leases which have accrued but unpaid Leasing Costs as
of the date hereof. Brandywine OP shall be responsible for payment of those
Leasing Costs for which it is designated as the responsible party on such
schedule, and Tysons Partnership or the applicable Subsidiary Entity shall be
responsible for payment of those Leasing Costs for which it is designated as the
responsible party on such schedule. Brandywine OP shall not be responsible for
any Leasing Costs that arise by virtue of the renewal or extension of the term
or expansion of the space exercised after the Closing Date covered by any Lease
for which it is designated as the responsible party on such schedule.

                                  ARTICLE VIII
                               GENERAL PROVISIONS

         8.1. Condemnation. In the event of any actual or threatened taking,
pursuant to the power of eminent domain, of all or any portion of the Property,
or any proposed sale in lieu thereof, Brandywine OP shall give written notice
thereof to Prentiss promptly after Brandywine OP learns or receives notice
thereof. If all or any part of the Property is, or is to be, so condemned or
sold, Prentiss shall have the right to terminate this Agreement pursuant to
Section 9.3 hereof. If Prentiss elects not to terminate this Agreement, all
proceeds, awards and other payments arising out of such condemnation and sale
(actual or threatened) shall be retained by Tysons Partnership or the applicable
Subsidiary Entity, as the case may be, and there shall be no reduction in the
Special Units or Common Units issuable to Brandywine OP hereunder. If Prentiss
elects to terminate this Agreement by giving Brandywine OP written notice
thereof prior

                                      -40-
<PAGE>

to the Closing, the Deposit shall be promptly returned to Prentiss and all
rights and obligations of Brandywine OP and Prentiss hereunder (except those set
forth herein which expressly survive a termination of this Agreement) shall
terminate immediately.

         8.2. Risk of Loss. The risk of any loss or damage to the Property prior
to the recordation of the Deed shall remain upon Brandywine OP and Tysons
Partnership. If any such loss or damage occurs prior to Closing which exceeds
$200,000, Prentiss shall have the right to terminate this Agreement pursuant to
Section 9.3 hereof. If Prentiss elects not to terminate this Agreement pursuant
to the immediately preceding sentence or a loss or damage occurs prior to
Closing which does not exceed $200,000, all insurance proceeds and rights to
proceeds arising out of such loss or damage, less the reasonable expenses
incurred in securing the Property following a casualty, shall be retained by
Tysons Partnership at Closing, and Prentiss shall receive as a credit against
the number of Special Units and Common Units otherwise issuable by it at Closing
(as elected by Brandywine OP) in the amount of any deductibles under the
policies of insurance covering such loss or damage (with each Special Unit
valued at $50.00 and each Common Unit valued at the Applicable Share Price) and
there shall be no further reduction in the number of Special Units or Common
Units otherwise issuable by Prentiss at Closing. If Prentiss elects to terminate
this Agreement pursuant to this Section 8.2 by giving Brandywine OP written
notice thereof prior to the Closing, the Deposit shall be promptly returned to
Prentiss and all rights and obligations of Brandywine OP and Prentiss hereunder
(except those set forth herein which expressly survive a termination of this
Agreement) shall terminate immediately.

         8.3. Broker. There is no real estate broker involved in this
transaction. Prentiss warrants and represents to Brandywine OP that Prentiss has
not dealt with any real estate broker in connection with this transaction, nor
has Prentiss been introduced to the Property or to Brandywine OP by any real
estate broker, and Prentiss shall indemnify Brandywine OP and hold Brandywine OP
harmless from and against any claims, suits, demands or liabilities of any kind
or nature whatsoever arising on account of the claim of any other person, firm
or corporation to a real estate brokerage commission or a finder's fee or a
financial advisory fee as a result of having dealt with Prentiss, or as a result
of having introduced Prentiss to Brandywine OP or to the Property. In like
manner, Brandywine OP warrants and represents to Prentiss that Brandywine OP has
not dealt with any real estate broker in connection with this transaction, nor
has Brandywine OP been introduced to Prentiss by any real estate broker, and
Brandywine OP shall indemnify Prentiss and save and hold Prentiss harmless from
and against any claims, suits, demands or liabilities of any kind or nature
whatsoever arising on account of the claim of any person, firm or corporation to
a real estate brokerage commission or a finder's fee or a financial advisory fee
as a result of having dealt with Brandywine OP in connection with this
transaction. This provision shall survive any termination of this Agreement and
a closing of the transaction contemplated hereby.

         8.4. 8260 Greensboro. Prentiss covenants that: (i) as Managing Partner
of Tysons Partnership, it will not cause or permit Tysons Partnership or
Brandywine Tyson, L.P. directly or indirectly to sell 8260 Greensboro or the
Tyson Partnership Interest prior to January 5, 2004 without the prior consent of
Brandywine OP unless the (a) transaction complies with the

                                      -41-
<PAGE>

requirements of Section 1031 of the Internal Revenue Code of 1986, as amended,
and (b) Prentiss provides for the "bottom guaranty" by Brandywine OP, on terms
reasonably acceptable to Brandywine OP, of at least $16.2 million of
non-recourse debt on terms substantially similar to the terms of the existing
"bottom guaranty" by Brandywine OP in favor of Mass Mutual through January 5,
2004; (ii) Prentiss shall not refinance or repay the debt secured by 8260
Greensboro Drive prior to January 5, 2004 without Brandywine OP's consent
unless, prior to such refinancing or repayment, Prentiss shall provide for the
"bottom guaranty" by Brandywine OP on terms reasonably acceptable to Brandywine
OP of at least $16.2 million of non-recourse debt on terms substantially similar
to the terms of the existing guaranty by Brandywine OP in favor of Mass Mutual;
(iii) Prentiss shall not at any time prior to January 5, 2006 either transfer
the Tysons Partnership Interest or cause Tysons Partnership or Brandywine Tyson,
L.P. to directly or indirectly convey 8260 Greensboro to a party which is a
Related Party to Prentiss without the consent of Brandywine OP; and (iv) after
January 5, 2006 Prentiss shall notify Brandywine OP not less than forty-five
(45) days prior to its consummation of any transaction covered by clause (iii).
The term "Related Party" shall have the meaning set forth in each of Section
1239(b), Section 1239(c), Section 267(b) and Section 267(c) of the Code.
Notwithstanding anything herein to the contrary, at such time as the Common
Units and the Special Units have been redeemed or exchanged in full pursuant to
the Prentiss Partnership Agreement, then the provisions of this Section 8.4
shall be of no further force or effect.

                                   ARTICLE IX
            LIABILITY OF PRENTISS; INDEMNIFICATION BY BRANDYWINE OP;
                           DEFAULT; TERMINATION RIGHTS

         9.1. Liability of Prentiss. Except for obligations expressly assumed or
agreed to be assumed by Prentiss hereunder, Prentiss is not assuming any
obligations of Brandywine OP, Tysons Partnership, or any of the Subsidiary
Entities or any liability for claims arising out of any act, omission or
occurrence which occurs, accrues or arises prior to the Closing Date (except to
the extent such assumption occurs as a matter of law), and Brandywine OP hereby
indemnifies and holds Prentiss harmless from and against any and all claims,
costs, penalties, damages, losses, liabilities and expenses (including
reasonable attorneys' fees) that may at any time be incurred by Prentiss as a
result of (a) obligations of Brandywine OP (i) not expressly assumed or agreed
to be assumed by Prentiss hereunder or (ii) which Prentiss is assuming as a
matter of law, but not otherwise expressly assuming hereunder or under any
document to be executed on the Closing Date that relate, in the case of clauses
(i) and (ii), solely to any act, omission or occurrence which occurs, accrues or
arises prior to the Closing Date, or (b) acts, omissions or occurrences which
occur, accrue or arise prior to the Closing Date (excluding, in any event, in
the case of clauses (a) and (b), ordinary course accruals). Prentiss hereby
indemnifies and holds Brandywine OP harmless from and against any and all
claims, costs, penalties, damages, losses, liabilities and expenses (including
reasonable attorneys' fees) that may at any time be incurred by Brandywine OP as
a result of acts, omissions or occurrences relating to the Property arising and
accruing from and after the Closing Date. The provisions of this Section shall
survive the Closing of the transaction contemplated hereby.

                                      -42-
<PAGE>

         9.2. Indemnification by Brandywine OP. Brandywine OP hereby indemnifies
and holds Prentiss and Prentiss' officers, partners, directors, shareholders,
agents and employees (collectively, the "Indemnified Parties") harmless from and
against any and all claims, costs, penalties, damages, losses, liabilities and
expenses (including reasonable attorneys' fees) that may at any time be incurred
by Prentiss, whether incurred before or after Closing, as a result of any
inaccuracy or breach by Brandywine OP of any of its representations, warranties,
covenants or obligations set forth herein or in any other document delivered by
Brandywine OP pursuant hereto except for any breach or inaccuracy of any
representation or warranty as to which Brandywine OP has given Prentiss written
notice prior to Closing of the untruth or inaccuracy or of which Prentiss
otherwise had actual knowledge prior to the Closing and nevertheless elected to
consummate the Closing; provided, however, the foregoing knowledge limitation on
Brandywine OP's indemnity shall not limit Prentiss' remedy described in Section
9.3(a)(ii) hereof or in the last sentence of Section 9.3 hereof. The provisions
of this Section shall survive the Closing of the transaction contemplated hereby
as provided in Section 10.11 hereof, and shall, following any assignment of this
Agreement by Prentiss, continue in favor of the Indemnified Parties of the
original Prentiss hereunder as well the Indemnified Parties of any assignee
during said survival period.

         9.3. Default by Brandywine OP/Failure of Conditions Precedent. If any
condition set forth herein for the benefit of Prentiss cannot or will not be
satisfied prior to Closing, or upon the occurrence of any other event that would
entitle Prentiss to terminate this Agreement and its obligations hereunder, and
if Brandywine OP fails to cure any such matter or satisfy that condition within
ten (10) business days after notice thereof from Prentiss (or such other time
period as may be explicitly provided for herein), Prentiss, at its option, may
elect (a) to terminate this Agreement, in which event (i) the Deposit, less the
Independent Consideration, shall be promptly returned to Prentiss, (ii) if the
condition which has not been satisfied is a breach of a representation, warranty
or covenant known by Brandywine OP to have been inaccurate or misleading when
made, then Brandywine OP shall be obligated upon demand to reimburse Prentiss
for Prentiss' actual out-of-pocket inspection, financing and other costs related
to Prentiss' entering into this Agreement, inspecting the Property and preparing
for a Closing of the transaction contemplated hereby, including, without
limitation, Prentiss' attorneys' fees incurred in connection with the
preparation, negotiation and execution of this Agreement and in connection with
Prentiss' due diligence review, audits and preparation for a Closing up to an
aggregate amount equal to $100,000.00; provided, the foregoing shall not limit
or include the sums which may be payable by Brandywine OP pursuant to Section
9.6 below, and (iii) all other rights and obligations of Brandywine OP and
Prentiss hereunder (except those set forth herein which expressly survive a
termination of this Agreement) shall terminate immediately; (b) elect to proceed
to Closing; or (c) seek to enforce Brandywine OP's obligations hereunder by
specific performance. If Prentiss elects to proceed to Closing and there is
either a misrepresentation or breach of a warranty by Brandywine OP (other than
a breach of a representation or warranty of which Prentiss had actual knowledge
prior to the Closing and nevertheless elected to consummate the Closing) or the
breach of a covenant by Brandywine OP or a failure by Brandywine OP to perform
its obligations hereunder first discovered by Prentiss after the Closing Date,
Prentiss shall retain all remedies accruing as a result thereof, including,

                                      -43-
<PAGE>

but not limited to, the remedy of specific performance of Brandywine OP's
covenants and obligations and the remedy of the recovery of all reasonable
damages resulting from Brandywine OP's breach of warranty or covenant.
Notwithstanding the foregoing, if the condition which has not been satisfied is
a breach of one or more representations and warranties by Brandywine OP or
Brandywine Grande B, L.P. in this agreement and/or in any of the other documents
executed of even date herewith between Prentiss and Brandywine OP or any of
their respective affiliates (the "Other Documents"), Prentiss has elected to
proceed to Closing, and Prentiss can reasonably quantify the damage resulting
from such breach of representations and warranties with reasonable support for
such calculation of damages, then (i) if the aggregate damage is no greater than
$150,000.00 (the "First Threshold Level"), then Brandywine OP shall have no
obligation to either cure such breaches of representations and warranties or pay
Prentiss at Closing in the event Prentiss elects to close the transaction
described in this Agreement and the Other Documents; (ii) if such aggregate
damage is greater than the First Threshold Level but less than $1,500,000.00,
then Brandywine OP must prior to the Closing Date either cure such breaches of
representations and warranties to the reasonable satisfaction of Prentiss or
Brandywine OP shall pay Prentiss at the Closing an amount equal to the actual
damages as reasonably determined by Prentiss as aforesaid, less the First
Threshold Level; and (iii) in the event the aggregate damages resulting from
such breaches of representations and warranties would exceed $1,500,000.00, then
Prentiss may either (A) terminate this Agreement and the Other Documents, in
which event the Deposit (less the Independent Consideration) shall be promptly
refunded, or (B) Prentiss may close the transaction as described in this
Agreement and the other Transaction Documents and Prentiss shall be paid by
Brandywine OP and Brandywine Grande B, L.P. the amount of $1,350,000.00, which
amount shall be the maximum aggregate amount payable by Grande B, L.P. and
Brandywine OP under the last sentence of Section 9.3 of this Agreement and all
of the Other Documents.

         9.4. Indemnification by Prentiss. Prentiss hereby indemnifies and holds
Brandywine OP harmless from and against any and all claims, costs, penalties,
damages, losses, liabilities and expenses (including reasonable attorneys' fees)
that may at any time be incurred by Brandywine OP, whether incurred before or
after Closing, as a result of any inaccuracy or breach by Prentiss of any of its
representations, warranties, covenants or obligations set forth herein or in any
other document delivered by Prentiss pursuant hereto except for any breach or
inaccuracy of any representation or warranty as to which Prentiss has given
Brandywine OP written notice prior to Closing of the untruth or inaccuracy or of
which Brandywine OP otherwise had actual knowledge prior to the Closing and
nevertheless elected to consummate the Closing. The provisions of this Section
shall survive the Closing of the transaction contemplated hereby for the period
provided in Section 10.11.

         9.5. Default by Prentiss/Failure of Conditions Precedent. If any
condition set forth herein for the benefit of Brandywine OP (other than a
default by Prentiss) cannot or will not be satisfied prior to Closing, and if
Prentiss fails to satisfy that condition within ten (10) business days after
notice thereof from Brandywine OP (or such other time period as may be
explicitly provided for herein), Brandywine OP may, at its option, elect either
(a) to terminate this Agreement in which event the Deposit shall be promptly
returned to Prentiss and the parties

                                      -44-
<PAGE>

hereto shall be released from all further obligations hereunder except those
which expressly survive a termination of this Agreement, or (b) to waive its
right to terminate, and instead, to proceed to Closing. If, prior to Closing,
Prentiss defaults in performing any of its obligations under this Agreement
(including its obligation to purchase the Property), and Prentiss fails to cure
any such default within ten (10) business days after notice thereof from
Brandywine OP, then Brandywine OP' sole remedy for such default shall be either
(i) to terminate this Agreement and retain the Deposit or (ii) to pursue the
remedy of specific performance compelling Prentiss to accept the contribution of
the Tysons Partnership Interest and issue the Common Units and Special Units
pursuant to the provisions of this Agreement.

         9.6. Costs and Attorneys' Fees. In the event of any litigation or
dispute between the parties arising out of or in any way connected with this
Agreement, resulting in any litigation, then the prevailing party in such
litigation shall be entitled to recover its costs of prosecuting and/or
defending same, including, without limitation, reasonable attorneys' fees at
trial and all appellate levels. The provisions of this Section shall survive the
Closing of the transaction contemplated hereby.

         9.7. Limitation of Liability. Notwithstanding anything herein to the
contrary, except in the case of fraud by either party, the liability of each
party hereto resulting from the breach or default by either party shall be
limited to actual damages incurred by the injured party and except in the case
of fraud by either party, the parties hereto hereby waive their rights to
recover from the other party consequential, punitive, exemplary, and speculative
damages. The provisions of this Section 9.7 shall survive the Closing of the
transaction contemplated hereby.

                                   ARTICLE X
                            MISCELLANEOUS PROVISIONS

         10.1. Completeness; Modification. This Agreement constitutes the entire
agreement between the parties hereto with respect to the transactions
contemplated hereby and supersedes all prior discussions, understandings,
agreements and negotiations between the parties hereto. This Agreement may be
modified only by a written instrument duly executed by the parties hereto. Any
waiver of rights under this Agreement shall be effective only if in writing and
duly executed and delivered by the party against whom such waiver is asserted.

         10.2. Assignments. Prentiss may assign its rights hereunder without the
consent of Brandywine OP to any affiliate of Prentiss, in which event, except as
otherwise specified herein, such assignee shall be the "Prentiss" hereunder;
however, any such assignment shall not relieve the original Prentiss of its
obligations under this Agreement, including specifically the obligation to close
the purchase of the Property in accordance with this Agreement as though there
were no assignment.

         10.3. Successors and Assigns. This Agreement shall bind and inure to
the benefit of the parties hereto and their respective successors and assigns.

                                      -45-
<PAGE>

         10.4. Days. If any action is required to be performed, or if any
notice, consent or other communication is given, on a day that is a Saturday or
Sunday or a legal holiday in the jurisdiction in which the action is required to
be performed or in which is located the intended recipient of such notice,
consent or other communication, such performance shall be deemed to be required,
and such notice, consent or other communication shall be deemed to be given, on
the first business day following such Saturday, Sunday or legal holiday. Unless
otherwise specified herein, all references herein to a "day" or "days" shall
refer to calendar days and not business days.

         10.5. Governing Law. This Agreement and all documents referred to
herein shall be governed by and construed and interpreted in accordance with the
laws of the State of Delaware.

         10.6. Counterparts. To facilitate execution, this Agreement may be
executed in as many counterparts as may be required. It shall not be necessary
that the signature on behalf of both parties hereto appear on each counterpart
hereof. All counterparts hereof shall collectively constitute a single
agreement.

         10.7. Severability. If any term, covenant or condition of this
Agreement, or the application thereof to any person or circumstance, shall to
any extent be invalid or unenforceable, the remainder of this Agreement, or the
application of such term, covenant or condition to other persons or
circumstances, shall not be affected thereby, and each term, covenant or
condition of this Agreement shall be valid and enforceable to the fullest extent
permitted by law.

         10.8. Notices. All notices, requests, demands and other communications
hereunder shall be in writing and shall be delivered by hand, transmitted by
facsimile transmission, sent prepaid by Federal Express (or a comparable
overnight delivery service) or sent by the United States mail, certified,
postage prepaid, return receipt requested, at the addresses and with such copies
as designated below. Any notice, request, demand or other communication
delivered or sent in the manner aforesaid shall be deemed given or made (as the
case may be) when actually delivered to the intended recipient.

         If to Brandywine OP:     Brandywine Realty Trust
                                  14 Campus Boulevard, Suite 100
                                  Newtown Square, PA 19073-3780
                                  Attn: Brad A. Molotsky, General Counsel
                                  Fax No.: (610) 325-4628

         If to Prentiss:          Prentiss Properties Acquisition Partners, L.P.
                                  3860 West Northwest Highway, Suite 400
                                  Dallas, TX  75220
                                  Attn.: J. Kevan Dilbeck, General Counsel
                                  Fax No.: (214) 350-2409

                                      -46-
<PAGE>

         With a copy to:          Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                                  1700 Pacific Avenue, Suite 4100
                                  Dallas, TX 75201-4675
                                  Attn.: Randall M. Ratner, P.C.
                                  Fax No.: (214) 969-4343

         If to Escrow Agent:      Chicago Title Insurance Company
                                  2001 Bryan Street, Suite 1700
                                  Dallas, TX  75201
                                  Attn.: Ellen Schwab
                                  Fax No.: (214) 965-1629

or to such other address as the intended recipient may have specified in a
notice to the other party. Any party hereto may change its address or designate
different or other persons or entities to receive copies by notifying the other
party and Escrow Agent in a manner described in this Section.

         10.9. Escrow Agent. Escrow Agent referred to in the definition thereof
contained in Section 1.1 hereof has agreed to act as such for the convenience of
the parties without fee or other charges for such services as Escrow Agent.
Escrow Agent shall not be liable: (a) to any of the parties for any act or
omission to act except for its own willful misconduct; (b) for any legal effect,
insufficiency, or undesirability of any instrument deposited with or delivered
by Escrow Agent or exchanged by the parties hereunder, whether or not Escrow
Agent prepared such instrument; (c) for any loss or impairment of funds that
have been deposited in escrow while those funds are in the course of collection,
or while those funds are on deposit in a financial institution, if such loss or
impairment results from the failure, insolvency or suspension of a financial
institution; (d) for the expiration of any time limit or other consequence of
delay, unless a properly executed written instruction, accepted by Escrow Agent,
has instructed Escrow Agent to comply with said time limit; or (e) for the
default, error, action or omission of either party to the escrow. Escrow Agent,
in its capacity as escrow agent, shall be entitled to rely on any document or
paper received by it, believed by such Escrow Agent, in good faith, to be bona
fide and genuine. In the event of any dispute as to the disposition of the
Deposit or any other monies held in escrow, or of any documents held in escrow,
Escrow Agent may, if such Escrow Agent so elects, interplead the matter by
filing an interpleader action in a court of general jurisdiction in the county
or circuit where the Property is located (to the jurisdiction of which both
parties do hereby consent), and pay into the registry of the court the Deposit,
or deposit any such documents with respect to which there is a dispute in the
Registry of such court, whereupon such Escrow Agent shall be relieved and
released from any further liability as Escrow Agent hereunder. Escrow Agent
shall not be liable for Escrow Agent's compliance with any legal process,
subpoena, writ, order, judgment and decree of any court, whether issued with or
without jurisdiction, and whether or not subsequently vacated, modified, set
aside or reversed.

                                      -47-
<PAGE>

         10.10. Incorporation by Reference. All of the exhibits attached hereto
are by this reference incorporated herein and made a part hereof.

         10.11. Survival. All of the representations, warranties, covenants and
agreements of Brandywine OP and Prentiss made in, or pursuant to, this Agreement
shall survive Closing through the period ending twelve (12) months thereafter
and shall not merge into the Deed or any other document or instrument executed
and delivered in connection herewith; provided, however, the covenants in
Sections 2.4(b), 6.6, 7.6 and 8.4 shall survive for the time periods described
in such Sections, and the indemnities in this Agreement and the covenants in
Section 7.7 and the representation in Section 4.6 shall have an unlimited
survival. In the event a claim for indemnity is asserted in good faith prior to
expiration of the applicable survival period, the claim may be asserted and the
indemnity shall continue notwithstanding expiration of the survival period.

         10.12. Further Assurances. Brandywine OP and Prentiss each covenant and
agree to sign, execute and deliver, or cause to be signed, executed and
delivered, and to do or make, or cause to be done or made, upon the written
request of the other party, any and all agreements, instruments, papers, deeds,
acts or things, supplemental, confirmatory or otherwise, as may be reasonably
required by either party hereto for the purpose of or in connection with
consummating the transactions described herein. Brandywine OP agrees to promptly
correct any defect, error or omission which may be discovered in the contents of
this Agreement or in any of the Exhibits or Schedules hereto.

         10.13. No Partnership. This Agreement does not and shall not be
construed to create a partnership, joint venture or any other relationship
between the parties hereto except the relationship of Brandywine OP and Prentiss
specifically established hereby.

         10.14. Time of Essence. Time is of the essence with respect to every
provision hereof.

         10.15. Signatory Exculpation. The signatory(ies) for Brandywine OP and
Prentiss are executing this Agreement in his/their capacity as representative of
Brandywine OP and Prentiss, respectively, and not individually and, therefore,
shall have no personal or individual liability of any kind in connection with
this Agreement and the transactions contemplated by it. No recourse shall be had
for any obligation of Brandywine OP or Prentiss under this Agreement or under
any document executed in connection herewith or pursuant hereto, or for any
claim based thereon or otherwise in respect thereof, against any past, present
or future trustee, shareholder, officer, partner or employee of Brandywine
Realty Trust, Brandywine OP Properties Trust, Brandywine OP or Prentiss, whether
by virtue of any statute or rule of law, or by the enforcement of any assessment
or penalty or otherwise, all such liability being expressly waived and released
by the parties hereto and all parties claiming by, through or under them.

                                      -48-
<PAGE>

         10.16. Rules of Construction. The following rules shall apply to the
construction and interpretation of this Agreement:

                  (a) Singular words shall connote the plural number as well as
the singular and vice versa, and the masculine shall include the feminine and
the neuter.

                  (b) All references herein to particular articles, sections,
subsections, clauses or exhibits are references to articles, sections,
subsections, clauses or exhibits of this Agreement.

                  (c) The table of contents and headings contained herein are
solely for convenience of reference and shall not constitute a part of this
Agreement nor shall they affect its meaning, construction or effect.

                  (d) Each party hereto and its counsel have reviewed and
revised (or requested revisions of) this Agreement and have participated in the
preparation of this Agreement, and therefore any usual rules of construction
requiring that ambiguities are to be resolved against a particular party shall
not be applicable in the construction and interpretation of this Agreement or
any exhibits hereto.

                  (e) As used herein, the term or phrases "Effective Date,"
"date of this Agreement" or "date hereof" shall mean the first date Escrow Agent
is in receipt of this Agreement executed by Brandywine OP and Prentiss.

         10.17. SEC Reporting (8-K) Requirements. For the period of time
commencing on the date hereof and continuing through the second anniversary of
the Closing Date, and without limitation of other document production otherwise
required of Brandywine OP hereunder, Brandywine OP shall, from time to time,
upon reasonable advance written notice from Prentiss, provide Prentiss and its
representatives, with access to all financial and other information pertaining
to the period of Tysons Partnership's ownership and operation of the Property,
which information is relevant and reasonably necessary, in the opinion of
outside, third party accountants (the "Accountants") for Prentiss, to enable
Prentiss and its Accountants to prepare financial statements in compliance with
any or all of (a) Rule 3-05 or 3-14 of Regulation S-X of the Securities and
Exchange Commission (the "Commission"), as applicable; (b) any other rule issued
by the Commission and applicable to Prentiss or the Trust; and (c) any
registration statement, report or disclosure statement filed with the Commission
by Brandywine; and a representation letter, signed by the individual(s)
responsible for Brandywine OP's financial reporting, as prescribed by generally
accepted auditing standards promulgated by the Auditing Standards Division of
the American Institute of Certified Public Accountants, which representation
letter may be required by the Accountants in order to render an opinion
concerning Prentiss' or the Trust's financial statements.

                                      -49-
<PAGE>

         IN WITNESS WHEREOF, Prentiss and Brandywine OP have caused this
Agreement to be executed in their names by their respective duly authorized
representatives.

                           BRANDYWINE OP:
                           -------------

                           BRANDYWINE OPERATING PARTNERSHIP, L.P., a Delaware
                           limited partnership

                           By:  Brandywine Realty Trust, a Maryland real estate
                                investment trust, its general partner

                                By:     /s/ Gerard H. Sweeney
                                        ----------------------------------------
                                Title:  President and Chief Executive Officer
                                        ----------------------------------------

                           Date of Execution:  March 14, 2001

                           PRENTISS:

                           PRENTISS PROPERTIES ACQUISITION PARTNERS, L.P.,
                           a Delaware limited partnership

                           By:  Prentiss Properties I, Inc., a Delaware
                                corporation, its general partner

                                By:     /s/ Thomas F. August
                                        ----------------------------------------
                                Title:  President and Chief Executive Officer
                                        ----------------------------------------

                               Date of  March 14, 2001
                            Execution:

                                      -50-
<PAGE>

                             RECEIPT OF ESCROW AGENT

         Chicago Title Insurance Company, as Escrow Agent, acknowledges receipt
of the sum of $300,050.00 by check or by wire transfer, from Brandywine OP as
described in Section 2.3 of the foregoing Agreement of Purchase and Sale, said
check or wire transfer to be held pursuant to the terms and provisions of said
Agreement.

         DATED this _____ day of __________, 2001.

                                  CHICAGO TITLE INSURANCE COMPANY

                                     By:
                                          --------------------------------------
                                   Name:
                                          --------------------------------------
                                  Title:
                                          --------------------------------------

                                      -51-<PAGE>

          Exhibit 10.6 - Agreement of Purchase and Sale (935 First Ave)

                         AGREEMENT OF PURCHASE AND SALE

                                     between

                          935 FIRST AVENUE ASSOCIATES,
                       a Pennsylvania limited partnership

                                  ("Prentiss")

                                       and

                     BRANDYWINE OPERATING PARTNERSHIP, L.P.,
                         a Delaware limited partnership

                                ("Brandywine OP")

<PAGE>

                                TABLE OF CONTENTS

                                                                            Page

ARTICLE I. DEFINITIONS.........................................................1
 1.1   Definitions.............................................................1
ARTICLE II. PURCHASE AND SALE; DEPOSIT; PAYMENT OF
PURCHASE PRICE; STUDY PERIOD...................................................7
 2.1   Purchase and Sale.......................................................8
 2.2   Payment of Purchase Price...............................................8
 2.3   Deposit.................................................................8
 2.4   Deliveries..............................................................8
ARTICLE III. PRENTISS' REPRESENTATIONS AND WARRANTIES.........................11
 3.1   Organization and Power.................................................11
 3.2   Authorization, Execution and Disclosure................................12
 3.3   Non-contravention......................................................12
 3.4   No Special Taxes.......................................................12
 3.5   Compliance with Existing Laws and Restrictive Covenants................12
 3.6   Personal Property......................................................13
 3.7   Operating Agreements...................................................13
 3.8   Condemnation Proceedings; Roadways.....................................13
 3.9   Actions or Proceedings.................................................13
 3.10  Bankruptcy.............................................................13
 3.11  Hazardous Substances...................................................13
 3.12  Parties in Possession..................................................14
 3.13  Leases.................................................................14
 3.14  Leased Property........................................................14
 3.15  No Unpaid Charges......................................................14
 3.16  Access.................................................................15
 3.17  No Commitments.........................................................15
 3.18  Prentiss Is Not a "Foreign Person".....................................15
 3.19  Leasing Commissions....................................................15
 3.20  Other Agreements.......................................................15
 3.21  Existing Secured Indebtedness..........................................15
 3.22  Employment on "At-Will" Basis..........................................15
 1.1   Architect's............................................................16
 3.23  Agreement..............................................................16
 3.24  Budget.................................................................16
 3.25  LIMITATIONS ON REPRESENTATIONS AND WARRANTIES..........................16

                                       i
<PAGE>

ARTICLE IV. BRANDYWINE OP'S REPRESENTATIONS AND WARRANTIES....................18
 4.1   Organization and Power.................................................18
 4.2   Non-contravention......................................................18
 4.3   Litigation.............................................................18
 4.4   Bankruptcy.............................................................18
 4.5   Authorization, Execution and Disclosure................................18
ARTICLE V. CONDITIONS PRECEDENT...............................................19
 5.1   As to Brandywine OP's Obligations......................................19
 5.2   As to Prentiss' Obligations............................................20
ARTICLE VI. COVENANTS OF PRENTISS.............................................20
 6.1   Operating Agreements...................................................20
 6.2   Warranties and Guaranties..............................................21
 6.3   Insurance..............................................................21
 6.4   Operation of Property Prior to Closing.................................21
 6.5   Construction Agreements................................................22
 6.6   No Marketing...........................................................22
ARTICLE VII. CLOSING..........................................................23
 7.1   Closing................................................................23
 7.2   Prentiss' Deliveries...................................................23
 7.3   Brandywine OP's Deliveries.............................................25
 7.4   Mutual Deliveries......................................................25
 7.5   Closing Costs..........................................................25
 7.6   Expense Allocations....................................................26
 7.7   Costs Associated with Payment of Total Project Costs...................27
 7.8   Leasing Commissions....................................................27
ARTICLE VIII. GENERAL PROVISIONS..............................................27
 8.1   Condemnation...........................................................27
 8.2   Risk of Loss...........................................................28
 8.3   Broker.................................................................28
 8.4   Bulk Sale..............................................................28
ARTICLE IX. LIABILITY OF BRANDYWINE OP; INDEMNIFICATION
BY PRENTISS; DEFAULT; TERMINATION RIGHTS......................................29
 9.1   Liability of Brandywine OP.............................................29
 9.2   Indemnification by Prentiss............................................29
 9.3   Default by Prentiss/Failure of Conditions Precedent....................30
 9.4   Indemnification by Brandywine OP.......................................31
 9.5   Default by Brandywine OP/Failure of Conditions Precedent...............31
 9.6   Costs and Attorneys' Fees..............................................31
 9.7   Limitation of Liability................................................32

                                       ii
<PAGE>

ARTICLE X. MISCELLANEOUS PROVISIONS...........................................32
10.1   Completeness; Modification.............................................32
10.2   Assignments............................................................32
10.3   Successors and Assigns.................................................32
10.4   Days...................................................................32
10.5   Governing Law..........................................................32
10.6   Counterparts...........................................................33
10.7   Severability...........................................................33
10.8   Notices................................................................33
10.9   Escrow Agent...........................................................33
10.10  Incorporation by Reference.............................................33
10.11  Survival...............................................................33
10.12  Further Assurances.....................................................33
10.13  No Partnership.........................................................33
10.14  Time of Essence........................................................33
10.15  Signatory Exculpation..................................................33
10.16  Rules of Construction..................................................33
10.17  Like-Kind Exchange.....................................................33
10.18  SEC Reporting (8-K) Requirements.......................................33

EXHIBITS
Exhibit A - Land
Exhibit B - Total Project Costs as of February 28, 2001
Exhibit C - Authorizations
Exhibit D - Permitted Title Exceptions

                                      iii
<PAGE>

                         AGREEMENT OF PURCHASE AND SALE

         THIS AGREEMENT OF PURCHASE AND SALE (this "Agreement") is made as of
this 14th day of March, 2001, between 935 FIRST AVENUE ASSOCIATES, a
Pennsylvania limited partnership and/or assigns (collectively, "Prentiss"), and
BRANDYWINE OPERATING PARTNERSHIP, L.P., a Delaware limited partnership
("Brandywine OP").

                             R E C I T A T I O N S:

         A. Prentiss is the owner of a fee estate in certain real property
located in the Commonwealth of Pennsylvania, as more particularly identified on
Exhibit A, attached hereto and made a part hereof for all purposes.

         B. Brandywine OP is desirous of acquiring such property from
Prentiss and Prentiss is desirous of conveying such property to Brandywine OP,
for the Purchase Price and upon the terms and conditions hereinafter set forth.

         NOW, THEREFORE, in consideration of the foregoing premises and in
consideration of the mutual covenants, promises and undertakings of the parties
hereinafter set forth, and for other good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged by the parties, it is
agreed:

                                    ARTICLE I
                                   DEFINITIONS

         1.1   Definitions. The following terms shall have the indicated
meanings:

               "Act of Bankruptcy" shall mean if a party hereto or any general
partner thereof shall (a) apply for or consent to the appointment of, or the
taking of possession by, a receiver, custodian, trustee or liquidator of itself
or of all or a substantial part of its property, (b) admit in writing its
inability to pay its debts as they become due, (c) make a general assignment for
the benefit of its creditors, (d) file a voluntary petition or commence a
voluntary case or proceeding under the Federal Bankruptcy Code (as now or
hereafter in effect), (e) be adjudicated a bankrupt or insolvent, (f) file a
petition seeking to take advantage of any other law relating to bankruptcy,
insolvency, reorganization, winding-up or composition or adjustment of debts,
(g) fail to controvert in a timely and appropriate manner, or acquiesce in
writing to, any petition filed against it in an involuntary case or proceeding
under the Federal Bankruptcy Code (as now or hereafter in effect), or (h) take
any corporate or partnership action for the purpose of effecting any of the
foregoing; or if a proceeding or case shall be commenced, without the
application or consent of a party hereto or any general partner thereof, in any
court of competent jurisdiction seeking (1) the liquidation, reorganization,
dissolution or winding-up, or the composition or readjustment of debts, of such

                                       1
<PAGE>

party or general partner, (2) the appointment of a receiver, custodian, trustee
or liquidator for such party or general partner or all or any substantial part
of its assets, or (3) other similar relief under any law relating to bankruptcy,
insolvency, reorganization, winding-up or composition or adjustment of debts,
and such proceeding or case shall continue undismissed for a period of ninety
(90) consecutive days; or an order (including an order for relief entered in an
involuntary case under the Federal Bankruptcy Code, as now or hereafter in
effect) judgment or decree approving or ordering any of the foregoing shall be
entered and continue unstayed and in effect, for a period of ninety (90)
consecutive days.

               "Applicable Laws" shall mean any applicable building, zoning,
subdivision, environmental, health, safety or other governmental laws, statutes,
ordinances, resolutions, rules, codes, regulations, orders or determinations of
any Governmental Authority or of any insurance boards of underwriters (or other
body exercising similar functions), or any restrictive covenants or deed
restrictions affecting the Property or the ownership, operation, use,
maintenance or condition thereof.

               "Architect's Agreement" shall mean the architect's and engineer's
agreement between Prentiss and Cathers & Associates dated March 22, 2000.

               "Assignment and Assumption Agreement" shall mean one or more
assignment and assumption agreements whereby, subject to the allocation
provisions in Section 7.7 hereof, (a) Prentiss (1) assigns and Brandywine OP
assumes the Architect's Agreement, to the extent assignable, (2) assigns all of
Prentiss' right, title and interest in and to the Intangible Personal Property
and the Authorizations, to the extent assignable, and (3) indemnifies, defends
and holds Brandywine OP and its agents, employees, officers, directors,
shareholders and contractors harmless with respect to all defaults, liabilities,
claims, costs and expenses (including, without limitation, reasonable attorneys'
fees) relating to acts or omissions accruing under such Architect's Agreement
before the Closing Date; and (b) Brandywine OP indemnifies, defends and holds
Prentiss harmless with respect to all defaults, liabilities, claims, costs and
expenses (including, without limitation, reasonable attorneys' fees) relating to
acts or omissions accruing under such Architect's Agreement after the Closing
Date.

               "Authorizations" shall mean all licenses, permits, approvals and
consents, including, without limitation, all architectural, mechanical,
structural and/or electrical plans and specifications, drawings, approvals and
licenses listed on Exhibit C attached hereto obtained in connection with the
Project, required by any governmental or quasi-governmental agency, body,
department, commission, board, bureau, instrumentality or officer, any owners
association created pursuant to deed restrictions affecting the Real Property or
otherwise appropriate with respect to the construction, ownership, operation,
leasing, maintenance, or use of the Property or any part thereof.

                                       2
<PAGE>

               "Brandywine OP" shall mean Brandywine Operating Partnership,
L.P., a Delaware limited partnership.

               "Brandywine OP's Objections" shall mean the objections defined as
such in Section 2.4(d) hereof.

               "Brandywine OP's Organizational Documents" shall mean the
organizational documents and all amendments thereto of Brandywine OP.

               "Budget" shall have the meaning ascribed to such term in Section
2.4(b)(4) hereof.

               "Closing" shall mean the Closing of the purchase and sale of the
Property pursuant to this Agreement and shall be deemed to occur on the Closing
Date.

               "Closing Date" shall mean the date on which the Closing occurs.

               "Closing Documents" shall mean the documents defined as such in
Section 7.1 hereof.

               "Deed" shall mean that certain special warranty deed conveying
title to the Land and subject only to Permitted Title Exceptions affecting each
such Parcel. If there is any difference between the description of the Land as
shown on Exhibit A attached hereto and the description of the Land shown on the
Survey, the description of the Land to be contained in the Deed and the
description of the Land set forth in the Title Commitment shall conform to the
description shown on the Survey.

               "Deposit" shall mean all amounts deposited from time to time with
Escrow Agent by Brandywine OP pursuant to Section 2.3 hereof, plus all interest
or other earnings that may accrue thereon. All cash Deposits shall be invested
by Escrow Agent in a commercial bank or banks acceptable to Brandywine OP at
money market rates, or in such other investments as shall be approved in writing
by Prentiss and Brandywine OP. The Deposit shall be held and disbursed by Escrow
Agent in strict accordance with the terms and provisions of this Agreement.

               "Development/Consulting Agreement" shall mean the
development/consulting agreement to be entered into by and between Brandywine OP
and Peter Hausmann containing terms and conditions mutually agreed upon by the
parties, that provides, among other things, for the completion of the Project as
directed by Brandywine OP in its sole discretion and for the payment to Hausmann
of $200,000.00 upon the completion of construction and issuance of a certificate
of occupancy for each building comprising the Project that is developed on the
Land.

               "Environmental Damages" shall mean all third-party claims,
judgments, damages, losses, penalties, fines, liabilities (including, without
limitation, punitive damages and strict liability), encumbrances, liens, costs

                                       3
<PAGE>

and expenses of investigation and defense of any claim, whether or not such is
ultimately defeated, and of any settlement or judgment, of whatever kind or
nature, contingent or otherwise, matured or unmatured, including, without
limitation, attorneys' fees and disbursements and consultants' fees, any of
which arise as a result of the existence of Hazardous Materials upon, about or
beneath the Property or migrating or threatening to migrate from the Property,
or as a result of the existence of a violation of Environmental Requirements
pertaining to the Property.

               "Environmental Requirements" shall mean (i) all applicable
statutes, regulations, rules, policies, ordinances, codes, licenses, permits,
orders, approvals, plans, authorizations, and similar items, of all Governmental
Authorities, and (ii) all judicial, administrative and regulatory decrees,
judgments and orders, in each case of (i) and (ii) relating to the protection of
human health or the environment from Hazardous Materials and health and safety
of employees or the public from Hazardous Materials, including, without
limitation, all requirements thereof pertaining to reporting, licensing,
permitting, investigation and remediation of emissions, discharges, releases or
threatened releases of Hazardous Materials into the air, surface water,
groundwater or land, or relating to the manufacture, processing, distribution,
use, treatment, storage, disposal, transport or handling of Hazardous Materials.

               "Escrow Agent" shall mean Chicago Title Insurance Company, whose
address is 2001 Bryan Street, Suite 1700, Dallas, Texas 75201, Attention: Ellen
Schwab.

               "FIRPTA Certificate" shall mean the affidavit of Prentiss under
Section 1445 of the Internal Revenue Code, as amended, certifying that Prentiss
is not a foreign corporation, foreign partnership, foreign trust, foreign estate
or foreign person (as those terms are defined in the Internal Revenue Code and
regulations promulgated thereunder), in form and substance satisfactory to
Brandywine OP.

               "Governmental Authority" shall mean any federal, state, county,
municipal or other government or any governmental or quasi-governmental agency,
department, commission, board, bureau, officer or instrumentality, foreign or
domestic, or any of them.

               "Hazardous Materials" shall mean any chemical substance: (i)
which is or becomes defined as a "hazardous substance," "hazardous waste,"
"hazardous material," "pollutant," "contaminant," or "toxic," "explosive,"
"corrosive," "flammable," "infectious," "radioactive," "carcinogenic," or
"mutagenic" material under any law, regulation, rule, order, or other authority
of the federal, state or local governments, or any agency, department,
commission, board, or instrumentality thereof, regarding the protection of human
health or the environment from such chemical substances including, but not
limited to, the following federal laws and their amendments, analogous state and
local laws, and any regulations promulgated thereunder: the Clean Air Act, the
Clean Water Act, the Oil Pollution Control Act, the Comprehensive Environmental
Response, Compensation, and Liability Act of 1986, the Emergency Planning and

                                       4
<PAGE>

Community Right to Know Act, the Solid Waste Disposal Act, the Resource
Conservation and Recovery Act, the Safe Drinking Water Act, the Federal
Insecticide, Fungicide and Rodenticide Act, and the Toxic Substances Control
Act, including, without limitation, asbestos and gasoline and other petroleum
products (including crude oil or any fraction thereof); (ii) without limitation,
which contains gasoline, diesel fuel or other petroleum hydrocarbons; (iii)
without limitation, which contains asbestos-containing materials or urea
formaldehyde foam insulation; or (iv) without limitation, radon gas; provided,
however, the term "Hazardous Materials" shall not include de minimis quantities
of substances of kinds and in amounts ordinarily and customarily used or stored
in properties similar to the Property for the purposes of cleaning or other
maintenance or operations and otherwise in compliance with Environmental
Requirements.

               "Improvements" shall mean all buildings, improvements, fixtures
and other items of real estate located on the Land, if any.

               "Insurance Policies" shall mean all policies of insurance
maintained by or on behalf of Prentiss pertaining to the Property, its
operation, or any part thereof.

               "Intangible Personal Property" shall mean all intangible personal
property, if any, owned or possessed by Prentiss and used in connection with the
ownership, operation, leasing, occupancy or maintenance of the Property,
including, without limitation, (1) Prentiss' exclusive right to use any trade
names associated with the Property and all variations thereof (other than
variants of Prentiss OP's legal name, all rights to which shall be retained by
Prentiss), (2) the Authorizations, (3) utility and development rights and
privileges, general intangibles, business records, plans and specifications
pertaining to the Real Property, and (4) any unpaid award for taking by
condemnation or any damage to the Land by reason of a change of grade or
location of or access to any street or highway.

               "Land" shall mean that certain parcel of real estate lying and
being in the and the Commonwealth of Pennsylvania, as more particularly
described on Exhibit A attached hereto, together with all easements, rights,
privileges, remainders, reversions and appurtenances thereunto belonging or in
any way appertaining, and all of the estate, right, title, interest, claim or
demand whatsoever of Prentiss therein, in the streets and ways adjacent thereto
and in the beds thereof, either at law or in equity, in possession or
expectancy, now or hereafter acquired.

               "Leased Property" shall mean all leased items of Tangible
Personal Property.

               "Leases" shall mean all leases, tenancies and other rights of
occupancy or use for any portion of the Real Property and leasehold estate, if
any, together with any and all amendments thereto.

                                       5
<PAGE>

               "Limited Partner" shall mean the entities defined collectively as
the Limited Partner in the Partnership Agreement.

               "Operating Agreements" shall mean all management, service, supply
and maintenance contracts, if any, in effect with respect to the Property and
all other contracts that affect the Property or are otherwise related to the
construction, development, ownership, operation, occupancy or maintenance of the
Property including, the Architect's Agreement.

               "Owner's Title Policy" shall mean an owner's policy of title
insurance for the Land issued to Brandywine OP by the Title Company, pursuant to
which the Title Company insures Brandywine OP's ownership of fee simple title to
the Land subject only to Permitted Title Exceptions. The Owner's Title Policy
shall insure Brandywine OP in the amount of the Purchase Price and shall be
acceptable in form and substance to Brandywine OP. Brandywine OP may require
such deletions of standard exceptions and such title endorsements as are legally
available and customarily required by institutional investors purchasing
property comparable to the Property in each State where the Property is
situated. The description of the Land in the Owner's Title Policy shall be by
courses and distances or by reference to a legal, subdivided lot and shall be
identical to the description shown on the Survey.

               "Partnership Agreement" shall mean the 935 First Avenue
Associates Agreement of Limited Partnership dated as of October 22, 1999 among
Prentiss and the Limited Partner.

               "Permitted Title Exceptions" shall mean those exceptions to title
to the Real Property that are satisfactory to Brandywine OP as determined
pursuant to Section 2.4(d) hereof and listed on Exhibit D.

               "Prentiss' Organizational Documents" shall mean the
organizational documents and all amendments thereto of Prentiss.

               "Prentiss OP" shall mean Prentiss Properties Acquisition
Partners, L.P., a Delaware limited partnership and the general partner of
Prentiss.

               "Project" shall mean the construction of (i) an approximately
103,000 square foot office building currently under development and (ii) an
additional office building contemplated to be constructed, each as contemplated
by the Authorizations on the Land.

               "Property" shall mean collectively the Real Property and the
Personal Property.

               "Purchase Price" shall mean the sum of (a) $5,700,000.00, plus
(b) Total Project Costs as of the Closing Date, payable in the manner described
in Section 2.2 hereof. In addition, as provided in Section 2.2, the Limited
Partner shall also be paid, at Closing, a one time payment of $200,000.00 to be
allocated among the Limited Partners in accordance with their respective
percentage interests set forth in the Partnership Agreement.

                                       6
<PAGE>

               "Real Property" shall mean the Land and the Improvements.

               "Submission Matters" shall mean all items Prentiss is required to
deliver to Prentiss pursuant to Section 2.4(b) hereof.

               "Survey" shall mean the survey defined as such in and prepared
pursuant to Section 2.4(d) hereof.

               "Tangible Personal Property" shall mean the items of tangible
personal property consisting of all furniture, fixtures, equipment, machinery
and other personal property that has been ordered with respect to the Project
(e.g., steel), if any.

               "Title Commitment" shall mean the title commitment and exception
documents defined as such in Section 2.4(d) hereof.

               "Title Company" shall mean Fidelity National Title Insurance
Company or other title insurance underwriter selected by Brandywine OP.

               "Total Project Costs" shall mean the construction costs incurred
in the development of the Project, including, without limitation, demolition
costs, site preparation costs, permit fees, architect's and engineer's fees,
impact fees, hard and soft construction costs, the total amount of which Total
Project Costs incurred as of February 28, 2001 (the "Approved Cost Date") is
specifically listed on Exhibit B hereto. Total Project Costs shall also include
additional costs incurred in the development of the Project that are incurred
between the Approved Cost Date and Closing Date, specifically in accordance with
Section 6.4(g).

               "UCC Reports" shall mean the reports defined as such in Section
2.4(d) hereof.

               "Utilities" shall mean public sanitary and storm sewers, natural
gas (if any), telephone, public water facilities, electrical facilities and all
other utility facilities and services (if any) necessary or appropriate for the
operation and occupancy of the Property as an office building.

               "Warranties and Guaranties" shall mean all warranties and
guaranties relating to the Improvements, or the Tangible Personal Property or
any part thereof.

                                       7
<PAGE>

                                   ARTICLE II
             PURCHASE AND SALE; DEPOSIT; PAYMENT OF PURCHASE PRICE;
                                  STUDY PERIOD

         2.1   Purchase and Sale. On the Closing Date, Prentiss agrees to sell
and Brandywine OP agrees to purchase the Property in accordance with and subject
to the other terms and conditions set forth herein.

         2.2   Payment of Purchase Price. The Purchase Price shall be paid to
Prentiss in the following manner:

               (a)  Brandywine OP shall receive a credit against the Purchase
Price in an amount equal to the cash Deposit.

               (b)  Brandywine OP shall pay the amount by which the Purchase
Price exceeds the sum of the cash Deposit, as adjusted in the manner specified
in Article VII and as set forth below, to Prentiss at Closing by making a wire
transfer of immediately available funds to the account of Prentiss.

               (c)  In addition, Brandywine OP shall pay at Closing the
additional sum of $200,000.00 to the Limited Partner to be allocated among the
Limited Partner in accordance with the respective percentage interests set forth
in the Partnership Agreement.

         2.3   Deposit. Within three (3) days after the execution hereof by both
Prentiss and Brandywine OP and as a condition precedent to the effectiveness of
this Agreement, Brandywine OP shall deliver to Escrow Agent a wire transfer or
check (a) in the sum of Fifty Dollars ($50.00) (the "Independent
Consideration"), payable to the order of Prentiss representing the Independent
Consideration for Prentiss' execution of this Agreement (which check or the
proceeds of which wire transfer shall thereafter be delivered by Escrow Agent to
Prentiss), and (b) in the sum of $5,000,000.00 (the proceeds of which wire
transfer or check Escrow Agent shall deposit and invest in an interest bearing
account at a financial institution acceptable to Brandywine OP or as otherwise
agreed to in writing by Prentiss and Brandywine OP). The proceeds of the wire
transfer or check are referred to herein as the "Deposit" and Escrow Agent shall
hold and invest the Deposit pursuant to the terms, conditions and provisions of
this Agreement. All accrued interest on the Deposit shall become part of the
Deposit. The Deposit (regardless of whether it is the proceeds of a wire
transfer or check) shall be either (a) returned to Brandywine OP pursuant
hereto, or (b) paid to Prentiss pursuant hereto. For purposes of reporting
earned interest with respect to the Deposit, Prentiss' Federal Tax
Identification Number is 74-2935544, and Brandywine OP's Federal Tax
Identification Number is 23-2862640.

         2.4   Deliveries.

               (a)  Brandywine OP and its agents, contractors and duly
authorized representatives have completed, at Brandywine OP's expense, such
economic, surveying, engineering, topographic, environmental, marketing and
other tests, studies and investigations as Brandywine OP deemed appropriate.

                                       8
<PAGE>

               (b)  Prentiss has delivered or made available at the Property the
following to Brandywine OP, to the extent reasonably available to Prentiss:

                    (1)  Copies of all Authorizations including, without
         limitation, all certificates of occupancy, permits, authorizations,
         approvals (including drawings and enacting ordinances, if any), special
         exceptions, variances, and licenses issued by Governmental Authorities
         having jurisdiction over the Property and copies of all certificates
         issued by the local board of fire underwriters (or other body
         exercising similar functions) relating to the Property. For the purpose
         of this Agreement any Submission Matters in the possession of Prentiss,
         Prentiss OP or Prentiss' management company shall be deemed to be
         "reasonably available to Prentiss."

                    (2)  A construction budget for the estimated costs to
         complete construction of the Project (the "Budget").

                    (3)  All existing surveys and title policies for the
         Property that are reasonably available to Prentiss.

                    (4)  To the extent in Prentiss' possession or reasonably
         available to Prentiss, any information in Prentiss' possession or
         reasonably available to Prentiss regarding current renditions or
         assessments on the Property or notices relative to change in valuation
         for ad valorem taxes.

                    (5)  A complete list of all Warranties and Guaranties in
         effect as of the date of this Agreement, if any, and complete copies of
         all such Warranties and Guaranties.

                    (6)  Copies of all soil tests, structural engineering tests,
         inspection reports, asbestos surveys, masonry tests, percolation tests,
         water, oil, gas, mineral, radon, formaldehyde, PCB or other
         environmental tests, audits or reports, market studies and site plans
         related to the Property in Prentiss' possession or reasonably available
         to Prentiss, together with copies of any and all correspondence,
         reports and other written documentation regarding the environmental
         aspects of the property or any toxic substances or equipment affecting
         or related to the Property.

                    (7)  Copies of complete sets of all architectural,
         mechanical, structural and/or electrical plans and specifications used
         in connection with the construction of or alterations or repairs to the
         Property.

                    (8)  Copy of the Architect's Agreement for the Property.

                    (9)  Parking, structural, mechanical or other engineering
         reports or studies related to the Property.

                                       9
<PAGE>

                    (10) Copies of all approvals from any owners associations
         having jurisdiction over the Real Property and copies of all
         correspondence from any such owners association.

         From execution of this Agreement and thereafter until the Closing,
Prentiss shall make available to Brandywine OP, copies of all materials,
correspondence, books, records, financial statements, operating statements and
any and all other materials or information relating to the Property which come
into Prentiss' possession or control or are otherwise reasonably available to
Prentiss from and after the date on which the Submission Matters were delivered
to Brandywine OP.

         Notwithstanding anything herein to the contrary, although Brandywine OP
has not received all of the deliveries described in this Section 2.4(b),
Brandywine OP has completed its feasibility study pursuant to Section 2.4(a) but
reserves the right to require, and Prentiss hereby agrees to deliver to the
extent available to it, any item described in Section 2.4(b) not previously
delivered at any time during the period expiring six (6) months after the
Closing Date, which agreement shall survive the Closing Date for such six (6)
month period.

               (c)  Brandywine OP shall indemnify and defend Prentiss against
any loss, damage or claim for personal injury or property damage (including
reasonable attorney's fees) arising from the entry upon the Property pursuant to
this Section 2.4 by Brandywine OP or any agents, contractors or employees of
Brandywine OP. Brandywine OP, at its own expense, shall restore any damage to
the Property caused by any of the tests or studies made by Brandywine OP. This
provision shall survive any termination of this Agreement and a closing of the
transaction contemplated hereby.

               (d)  The Permitted Title Exceptions are listed on Exhibit D to
this Agreement. Any title exceptions not listed on Exhibit D shall be deemed to
be objectionable by Brandywine OP and shall be handled in accordance with this
Section 2.4. (collectively, "Brandywine OP's Objections"). If any of Brandywine
OP's Objections consist of delinquent taxes, mortgages, deeds of trust, security
agreements, construction or mechanics' liens, tax liens or other liens or
charges in a fixed sum or capable of computation as a fixed sum, then, to that
extent, notwithstanding anything herein to the contrary, Prentiss shall be
obligated to pay and discharge (or bond against in a manner sufficient to cause
the Title Company to insure over such Brandywine OP's Objections) any such
Brandywine OP's Objections and Escrow Agent is authorized to pay and discharge
at Closing such Brandywine OP's Objections to the extent not paid and discharged
or bonded against at Closing. Prentiss shall not be obligated to incur any
expenses to cure any non-monetary Brandywine OP's Objections (including, without
limitation, any lis pendens filed against the Property) unless Prentiss agrees
to cure such non-monetary Brandywine OP's Objections as hereinafter provided.
Prentiss shall notify Brandywine OP on or before the Closing Date whether
Prentiss agrees to cure such non-monetary Brandywine OP's Objections. If
Prentiss notifies Brandywine OP in writing on or before the Closing Date that

                                       10
<PAGE>

Prentiss agrees to cure such non-monetary Brandywine OP's Objections, Prentiss
shall correct such non-monetary Brandywine OP's Objections on or before the
Closing Date to the reasonable satisfaction of Brandywine OP. If Prentiss does
not notify Brandywine OP on or before the Closing Date of its agreement to cure
such non-monetary Brandywine OP's Objections, Prentiss shall be deemed to have
elected not to cure such non-monetary Brandywine OP's Objections, and Brandywine
OP shall elect (1) to waive such non-monetary Brandywine OP's Objections or (2)
to terminate this Agreement, in which case the Deposit shall be promptly
returned to Brandywine OP and the parties hereto shall be released from all
further obligations hereunder except those which expressly survive a termination
of this Agreement. Prentiss shall not, after the date of this Agreement, subject
the Real Property to or permit or suffer to exist any liens, encumbrances,
covenants, conditions, restrictions, easements or other title matters or seek
any zoning changes or take any other action which may affect or modify the
status of title without Brandywine OP's prior written consent. All title matters
listed on Exhibit D (other than those rendering title defeasible and delinquent
taxes, mortgages, deeds of trust, security agreements and other liens and
charges that are to be paid at Closing or bonded against as provided above)
shall be deemed Permitted Title Exceptions. Notwithstanding the foregoing,
Brandywine OP shall not be required to take title to the Real Property subject
to any matters which (i) may arise subsequent to the effective date of the Title
Commitment, UCC Reports and Survey examined by Brandywine OP during the Study
Period and (ii) impairs title to any portion of the Property and will not be
released or bonded against on or before the Closing Date. If a title exception
is disclosed by the Title Company which was not shown in the Title Commitment or
Survey and was not the result of Prentiss' acts or omissions, then, unless
Prentiss notifies Brandywine OP in writing by the Closing Date that Prentiss
agrees to take such action as may be necessary to release such title exception
on or before the Closing Date, Brandywine OP may (i) terminate this Agreement by
written notice to Prentiss, in which event the Deposit shall be promptly
returned to Brandywine OP and the parties hereto shall be released from all
further obligations hereunder except those which expressly survive a termination
of this Agreement, or (ii) waive its objections to such title exception and
consummate the transactions contemplated herein.

                                  ARTICLE III.
                    PRENTISS' REPRESENTATIONS AND WARRANTIES

         To induce Brandywine OP to enter into this Agreement and to acquire the
Property, Prentiss makes the following representations and warranties with
respect to the Property, upon each of which Prentiss acknowledges and agrees
that Brandywine OP is entitled to rely and has relied:

         3.1   Organization and Power. Prentiss is a limited partnership duly
formed, validly existing and in good standing under the laws of the Commonwealth
of Pennsylvania, and has all requisite powers and all material governmental
licenses, authorizations, consents and approvals to carry on its business as now
conducted and to enter into and perform its obligations hereunder and under any

                                       11
<PAGE>

document or instrument required to be executed and delivered on behalf of
Prentiss hereunder.

         3.2   Authorization, Execution and Disclosure. This Agreement has been
duly authorized by all necessary action on the part of Prentiss, has been duly
executed and delivered by Prentiss, constitutes the valid and binding agreement
of Prentiss and is enforceable in accordance with its terms, subject to the
effect of applicable bankruptcy, insolvency, reorganization, arrangement,
moratorium or other similar laws affecting the rights of creditors generally.
Except for the waiver of the special restrictions on sale set forth in Section
5.2 of the Partnership Agreement in favor of the Limited Partner in Prentiss
that are not affiliates of Prentiss, there is no other person or entity who has
an ownership interest in the Property or whose consent is required in connection
with Prentiss' performance of its obligations hereunder which has not been
obtained. Prentiss covenants to deliver a copy of this Agreement to the Limited
Partner, within one (1) business day of execution of this Agreement, in order to
trigger the Limited Partner rights under Section 5.2 of the Partnership
Agreement. The person executing this Agreement on behalf of Prentiss has the
authority to do so. Prentiss has not and will not intentionally conceal any
information regarding the Property.

         3.3   Non-contravention. The execution and delivery of, and the
performance by Prentiss of its obligations under, this Agreement do not and will
not (a) contravene, or constitute a default under, any provision of (i)
Prentiss' Organizational Documents, (ii) applicable law or regulation or any
agreement, judgment, injunction, order, decree or, subject to Section 3.2 above,
other instrument binding upon Prentiss or to which the Property is subject, the
result of which could have a material adverse effect on the value of the
Property or Prentiss' ability to convey the Property to Brandywine OP and/or
Prentiss' ability to perform its obligations under this Agreement, or (iii)
result in the creation of any lien or other encumbrance on any asset of
Prentiss. There are no outstanding agreements (written or oral) pursuant to
which Prentiss (or any predecessor to or representative of Prentiss) has agreed
to sell or has granted an option or right of first refusal to purchase the
Property or any part thereof.

         3.4   No Special Taxes. Prentiss has no knowledge of, nor has it
received any notice of, any special taxes or assessments relating to the
Property or any part thereof or any planned public improvements that may result
in a special tax or assessment against the Property.

         3.5   Compliance with Existing Laws and Restrictive Covenants. To
Prentiss' knowledge, Prentiss possesses all Authorizations available for the
current state of construction of the Project, each of which is valid and in full
force and effect, and no provision, condition or limitation of any of the
Authorizations has been breached or violated. Prentiss has received no notice
within the past year, of any existing or threatened violation of any provision
of any (a) Applicable Laws including, but not limited to, those of environmental
agencies or insurance boards of underwriters with respect to the ownership,
operation, use, maintenance or condition of the Property or any part thereof, or
requiring any repairs or alterations to the Property other than those that have

                                       12
<PAGE>

been made prior to the date hereof, and (b) restrictive covenants or deed
restrictions affecting the Real Property.

         3.6   Personal Property. There is no personal property being conveyed
by Prentiss hereunder, except for such personal property that has been ordered
with respect to the Project (e.g., steel), if any.

         3.7   Operating Agreements. Except for the Architect's Agreement, there
are no Operating Agreements or other contracts in effect with respect to the
Property of any nature whatsoever, written or oral.

         3.8   Condemnation Proceedings; Roadways. Prentiss has received no
notice of any condemnation or eminent domain proceeding pending or, to Prentiss'
knowledge, no such action is threatened, against the Property or any part
thereof. Prentiss has no knowledge of any change or proposed change in the
route, grade or width of, or otherwise affecting, any street, creek or road
adjacent to or serving the Real Property.

         3.9   Actions or Proceedings. There is no action, suit or proceeding
pending or known to Prentiss to be threatened against or affecting Prentiss in
any court, before any arbitrator or before or by any Governmental Authority
which (a) in any manner raises any question affecting the validity or
enforceability of this Agreement or any other agreement or instrument to which
Prentiss is a party or by which it is bound and that is or is to be used in
connection with, or is contemplated by, this Agreement, (b) is reasonably likely
to materially and adversely affect the business, financial position or results
of operations of Prentiss or the Property, (c) is reasonably likely to
materially and adversely affect the ability of Prentiss to perform its
obligations hereunder, or under any document to be delivered pursuant hereto,
(d) is reasonably likely to create a lien on the Property, any part thereof or
any interest therein or (e) is reasonably likely to otherwise materially and
adversely affect the Property, any part thereof or any interest therein or the
use, operation, condition or occupancy thereof.

         3.10  Bankruptcy. No Act of Bankruptcy has occurred with respect to
Prentiss.

         3.11  Hazardous Substances. To Prentiss' knowledge, neither Prentiss
nor any previous owner, tenant, occupant or user of the Property, nor any other
person, has engaged in or permitted any operations or activities upon, or any
use or occupancy of the Property or any portion thereof, for the purpose of or
in any way involving the handling, manufacture, treatment, storage, use,
generation, release, discharge, refining, dumping or disposal of any Hazardous
Materials on, under, in or about the Property in violation of any Applicable
Laws. To Prentiss' knowledge, no Hazardous Materials have migrated from or to
the Property upon, about, or beneath other properties in violation of any
Environmental Requirements. To Prentiss' knowledge, neither the Property nor its
existing or prior uses fail or failed to materially comply with Environmental
Requirements. Prentiss has no knowledge of any permits, licenses or other

                                       13
<PAGE>

authorizations which are required under any Environmental Requirements with
regard to the current uses of the Property which have not been obtained and
complied with. Prentiss has delivered all reports that reference the presence of
asbestos on the Property. To Prentiss' knowledge, the asbestos located on the
Property and identified in such report was removed fully by Prentiss' licensed
contractor in connection with the demolition of the Improvements in accordance
with all Environmental Requirements. To Prentiss' knowledge, neither Prentiss
nor any prior owner, occupant or user of the Property has received any written
notice concerning any alleged violation of Environmental Requirements in
connection with the Property or any liability for Environmental Damages in
connection with the Property for which Prentiss (or Brandywine OP after Closing)
may be liable. To Prentiss' knowledge, no Hazardous Materials are constructed,
deposited, stored or otherwise located on, under, in or about the Property in
violation of any Environmental Requirements. To Prentiss' knowledge, there
exists no writ, injunction, decree, order or judgment outstanding, nor any
lawsuit, claim, proceeding, citation, summons or investigation, pending or
threatened, relating to any alleged violation of Environmental Requirements on
the Property, or from the suspected presence of Hazardous Materials thereon, or
relating to any Environmental Damages. To Prentiss' knowledge, there are no
underground or above ground chemical treatment or storage tanks, or gas or oil
wells are located on the Property. The representations and warranties made by
Prentiss in this Section 3.11 shall be subject to the matters disclosed in the
(a) Phase I Environmental Report of Pennoni Associates, Inc. dated October 1,
1999 and (b) Asbestos Remediation Report prepared by Pennoni Associates, Inc.
dated October 19, 2000 and delivered by Prentiss to Brandywine OP pursuant to
Section 2.4(b)(6) hereof.

         3.12  Parties in Possession. There are no parties in possession of the
Property.

         3.13  Leases. There are no leases, concessions or occupancy agreements
in effect with respect to the Real Property.

         3.14  Leased Property. There are no leases in effect for leased
property.

         3.15  No Unpaid Charges. Subject to Section 7.7 hereof and other than
Total Project Costs, there are no unpaid charges, debts, liabilities, claims or
obligations arising from the construction, occupancy, ownership, use or
operation of the Property which could give rise to any mechanic's or
materialmen's or other statutory lien against the Property, or any part thereof;
however, Prentiss shall be responsible for obtaining lien waivers in accordance
with Section 7.7 hereof with respect to all sums paid or accrued as Total
Project Costs pursuant to Section 2.2 hereof. Prentiss represents and warrants
that the Total Project Costs listed on Exhibit B are true, complete and accurate
and fully reflect the costs incurred in connection with the Project through the
Approved Cost Date.

                                       14
<PAGE>

         3.16  Access. Prentiss has no knowledge of any pending or threatened
governmental proceeding or any other fact or condition which would limit or
result in the termination of the Property's existing access to and from public
streets or roads.

         3.17  No Commitments. No commitments have been made to any Governmental
Authority, utility company, school board, church or other religious body, or any
homeowners' association or any other organization, group or individual, relating
to the Property which would impose an obligation upon Brandywine OP to make any
contribution or dedication of money or land or to construct, install or maintain
any improvements of a public or private nature on or off the Property. Without
limiting the generality of the foregoing, Prentiss is not a party to any paving
agreements or undertakings, payback agreements, revenue bonds, utility debt
service expenses or other charges or expenses upon or relating to any of the
Property or applicable thereto, except for any of the foregoing delivered by
Prentiss pursuant to Section 2.4(b) listed on Exhibit C.

         3.18  Prentiss Is Not a "Foreign Person". Prentiss is not a "foreign
person" within the meaning of Section 1445 of the Internal Revenue Code, as
amended (i.e., Prentiss is not a foreign corporation, foreign partnership,
foreign trust, foreign estate or foreign person as those terms are defined in
the Internal Revenue Code and regulations promulgated thereunder).

         3.19  Leasing Commissions. No brokerage or leasing commissions or other
fees or compensation are due or payable, or, except as set forth in Section
5.4.2 of the Partnership Agreement, which will become due and payable as a
result of agreements in place or agreements to agree, to any person, firm,
corporation or other entity with respect to any lease or the sale of the
Property.

         3.20  Other Agreements. Except for the Limited Partner rights in the
Partnership Agreement, there are no options, contracts or other obligations
outstanding for the sale, exchange or transfer of any of the Property or any
interest therein which would be superior to the rights of Brandywine OP under
this Agreement or which would survive Closing.

         3.21  Existing Secured Indebtedness. There is no debt secured by liens
on the Real Property, or any portion thereof, which will not be released and
discharged as of the Closing.

         3.22  Employment on "At-Will" Basis. All persons and entities presently
employed in connection with the operation and maintenance of the Property are
employed on an "at will" basis, are dischargeable upon thirty (30) days' notice
and, unless otherwise directed by Brandywine OP, shall be terminated by Prentiss
as of Closing. There are no labor disputes pending, nor to the best of Prentiss'
knowledge, contemplated pertaining to the operation or maintenance of the
Property, or any part thereof. Prentiss has no employment agreements, either
written or oral, with any person which would require Brandywine OP to employ any
person after the date hereof or the Closing Date.

                                       15
<PAGE>

         3.23  Architect's Agreement. The Architect's Agreement between Prentiss
and Cathers and Associates dated March 22, 2000 is the only agreement in effect
on the date hereof with respect to the Project.

         3.24  Budget. The Budget is Prentiss' best estimate, as of the date
hereof, of Total Project Costs incurred and to be incurred to complete the
Project.

         3.25  LIMITATIONS ON REPRESENTATIONS AND WARRANTIES. BRANDYWINE OP
HEREBY AGREES AND ACKNOWLEDGES THAT, EXCEPT AS SET FORTH IN THIS ARTICLE III, OR
AS OTHERWISE EXPRESSLY STATED HEREIN OR IN THE DEED OR IN ANY DOCUMENTS EXECUTED
IN CONNECTION HEREWITH, NEITHER PRENTISS NOR ANY AGENT, ATTORNEY, EMPLOYEE OR
REPRESENTATIVE OF PRENTISS HAS MADE ANY REPRESENTATION WHATSOEVER REGARDING THE
SUBJECT MATTER OF THIS AGREEMENT, OR ANY PART HEREOF, INCLUDING (WITHOUT
LIMITING THE GENERALITY OF THE FOREGOING) REPRESENTATIONS OR WARRANTIES AS TO
THE PHYSICAL NATURE OR CONDITION OF THE PROPERTY OR THE CAPABILITIES THEREOF,
AND THAT BRANDYWINE OP, IN EXECUTING, DELIVERING AND/OR PERFORMING THIS
AGREEMENT, DOES NOT RELY UPON ANY STATEMENT AND/OR INFORMATION TO WHOMEVER MADE
OR GIVEN, DIRECTLY OR INDIRECTLY, ORALLY OR IN WRITING, BY ANY INDIVIDUAL, FIRM
OR CORPORATION EXCEPT THOSE EXPRESSLY CONTAINED HEREIN OR DELIVERED PURSUANT
THERETO OR IN ANY DOCUMENTS EXECUTED IN CONNECTION HEREWITH. EXCEPT AS OTHERWISE
PROVIDED HEREIN, BRANDYWINE OP AGREES TO TAKE THE PROPERTY "AS IS," AS OF THE
DATE HEREOF, REASONABLE WEAR AND TEAR EXCEPTED. IN ADDITION, EXCEPT AS SET FORTH
HEREIN, PRENTISS MAKES NO REPRESENTATIONS OR WARRANTIES REGARDING THE COMPLIANCE
WITH ANY ENVIRONMENTAL REQUIREMENTS, INCLUDING THE EXISTENCE IN OR ON THE
PROPERTY OF HAZARDOUS MATERIALS. THE PROVISIONS OF THIS PARAGRAPH SHALL SURVIVE
THE CLOSING OR ANY TERMINATION HEREOF.

Each of the representations and warranties contained in this Article III and its
various subparagraphs are intended for the benefit of Brandywine OP and may be
waived in whole or in part by Brandywine OP. All rights and remedies arising in
connection with the untruth or inaccuracy of any such representations and
warranties shall survive the Closing of the transaction contemplated hereby as
provided in Section 10.11 hereof, except to the extent that Prentiss gives
Brandywine OP written notice prior to Closing of the untruth or inaccuracy of
any representation or warranty, Brandywine OP otherwise obtains actual knowledge
prior to Closing of the untruth or inaccuracy of any representation or warranty,
and Brandywine OP nevertheless elects to close this transaction; provided,
however that the foregoing exception shall not apply with respect to any leasing
commission claimed under Section 5.4.2 of the Partnership Agreement. Brandywine
OP shall be deemed to have actual knowledge of the untruth or inaccuracy of any

                                       16
<PAGE>

representation or warranty only if (i) Brandywine OP receives written notice
from Prentiss satisfying the foregoing requirements, or (ii) Gerard H. Sweeney,
George Hasenecz, Michael Diliberto, Suzanne Stumpf or Brad A. Molotsky has
actual knowledge of any such untruth or inaccuracy. Except to the extent
otherwise expressly provided in the immediately preceding sentence, no
investigation, audit, inspection, review or the like conducted by or on behalf
of Brandywine OP shall be deemed to terminate the effect of any such
representations, warranties and covenants, it being understood that Brandywine
OP has the right to rely thereon and that each such representation and warranty
constitutes a material inducement to Brandywine OP to execute this Agreement and
to close the transaction contemplated hereby and to pay the Purchase Price to
Prentiss.

If any of Prentiss' representations and warranties made hereunder are found by
Brandywine OP to be incorrect prior to Closing to the extent they affect the
Property or its operation in any material respect, Brandywine OP shall inform
Prentiss in writing and Brandywine OP's sole remedy, except as otherwise
expressly provided in clause (a)(ii) of the first sentence of Section 9.3 hereof
or the last sentence of Section 9.3 hereof, shall be termination of this
Agreement on account thereof and refund of the Deposit. If Brandywine OP elects
not to so terminate this Agreement, any remedy of Brandywine OP for breach of
such warranties and representations made prior to the Closing shall be deemed to
be irrevocably waived. Notwithstanding anything to the contrary contained in
this Article, if Prentiss breaches any representation or warranty made by
Prentiss and if prior to Closing Brandywine OP notifies Prentiss that it elects
to terminate this Agreement on account of such breach, Prentiss may by written
notice to Brandywine OP given or before the Closing Date agree to cure the
breach (which breach must be cured on or before the Closing Date), and
Brandywine OP shall thereupon be obligated to close the transaction and accept
such cure as Brandywine OP's sole remedy for such breach.

The term "to Prentiss' knowledge" or similar phrase shall mean the knowledge of
Prentiss OP's chief executive officer, general counsel, chief financial officer,
Hank Gulbrandsen and Peter Hausmann, and the current building engineer, property
manager and leasing agent (collectively, "Prentiss' Personnel with Knowledge")
for the Property and such inquiry shall include the direction by Prentiss to
such persons to review all files in their possession relating to the operation,
ownership, maintenance and management of the Property. Prentiss covenants that
if prior to Closing Prentiss obtains actual knowledge that any of the facts
represented and warranted by Prentiss under this Agreement are or become untrue
or inaccurate in any material respect, it will promptly inform Brandywine OP in
writing of its discovery.

Prentiss' Personnel with Knowledge shall not have any personal liability under
this Agreement in their respective capacities as officers and/or directors of
Prentiss.

                                       17
<PAGE>

                                  ARTICLE IV.
                 BRANDYWINE OP'S REPRESENTATIONS AND WARRANTIES

         To induce Prentiss to enter into this Agreement and to convey the
Property, Brandywine OP hereby makes the following representations and
warranties, upon each of which Brandywine OP acknowledges and agrees that
Prentiss is entitled to rely and has relied:

         4.1   Organization and Power. Brandywine OP is a limited partnership,
duly formed, validly existing and in good standing under the laws of the State
of Delaware, and has all requisite partnership powers and all material
governmental licenses, authorizations, consents and approvals required to carry
on its businesses as now conducted and to enter into and perform its obligations
under this Agreement and any document or instrument required to be executed and
delivered on behalf of Brandywine OP hereunder. Brandywine OP has the financial
capability to acquire the Property pursuant to this Agreement.

         4.2   Non-contravention. The execution and delivery of this Agreement
and the performance by Brandywine OP of its obligations hereunder do not and
will not contravene, or constitute a default under, any provisions of Brandywine
OP's Organizational Documents or applicable law or regulation, or any agreement,
judgment, injunction, order, decree or other instrument binding upon Brandywine
OP.

         4.3   Litigation. There is no action, suit or proceeding, pending or
known to be threatened, against or affecting Brandywine OP or Brandywine OP in
any court or before any arbitrator or before any Governmental Authority which
(a) in any manner raises any question affecting the validity or enforceability
of this Agreement or any other agreement or instrument to which Brandywine OP is
a party or by which it is bound and that is to be used in connection with, or is
contemplated by, this Agreement, (b) could materially and adversely affect the
business, financial position or results of operations of Brandywine OP, or (c)
could materially and adversely affect the ability of Brandywine OP to perform
its obligations hereunder, or under any document to be delivered pursuant
hereto.

         4.4   Bankruptcy. No Act of Bankruptcy has occurred with respect to
Brandywine OP.

         4.5   Authorization, Execution and Disclosure. This Agreement has been
duly authorized by all necessary action on the part of Brandywine OP, has been
duly executed and delivered by Brandywine OP, constitutes the valid and binding
agreement of Brandywine OP and is enforceable in accordance with its terms,
subject to the effect of applicable bankruptcy, insolvency, reorganization,
arrangement, moratorium or other similar laws affecting the rights of creditors
generally.

                                       18
<PAGE>

                                   ARTICLE V.
                              CONDITIONS PRECEDENT

         5.1   As to Brandywine OP's Obligations. Brandywine OP's obligations
hereunder are subject to the satisfaction of the following conditions precedent:

               (a)  Prentiss' Deliveries. Prentiss shall have delivered to or
for the benefit of Brandywine OP, on or before the Closing Date, all of the
documents and other information required of Prentiss pursuant to Sections 7.2
and 7.4 hereof.

               (b)  Representations, Warranties and Covenants; Obligations of
Prentiss; Certificate. All of Prentiss' representations and warranties made in
this Agreement shall be true and correct in all material respects as of the date
hereof and as of the date of Closing as if then made; Prentiss shall have
performed in all material respects all of its covenants and other obligations
under this Agreement; and Prentiss shall have executed and delivered to
Brandywine OP at Closing a certificate to the foregoing effect.

               (c)  Title Insurance. Good and indefeasible fee simple title to
the Land shall be insurable as such by the Title Company, subject only to
Permitted Title Exceptions as determined in accordance with Section 2.4 hereof
and including, without limitation, all applicable deletions of standard
exceptions and endorsements permitted under applicable state law which are
customarily required by institutional investors purchasing property comparable
to the Property.

               (d)  Utilities. All of the Utilities have been installed at least
to the Property line.

               (e)  Due Diligence Materials. All lists, schedules and other
documents furnished by Prentiss to Brandywine OP under this Agreement shall be
true and correct in all material respects, except for inaccuracies as to which
Brandywine OP was given written notice by Prentiss or otherwise had actual
knowledge prior to the execution of this Agreement.

               (f)  No Additional Proceedings. Except for matters as to which
Brandywine OP was given written notice by Prentiss or otherwise had actual
knowledge prior to the execution of this Agreement, on the Closing Date, there
shall be no (a) litigation pending or threatened, seeking (i) to enjoin the
consummation of the transactions contemplated hereunder, (ii) to recover title
to the Property, or any part thereof or any interest therein, (iii) to increase
substantially ad valorem taxes theretofore assessed against any of the Property,
or (iv) to enjoin the violation of any law, rule, regulation, restrictive
covenant or zoning ordinance that may be applicable to the Property.

                                       19
<PAGE>

               (g)  Consents from Parties to the Architect's Agreement. The
consents and agreements to be delivered at Closing required to assign, to the
extent assignable, the rights under the Architect's Agreement from Prentiss to
Brandywine OP.

               (h)  Limited Partner Rights. The rights of the Limited Partner
under Section 5.2 of the Partnership Agreement shall have terminated or have
been waived or deemed waived for the transaction described in this Agreement.

Each of the conditions contained in this Section 5.1 are intended for the
benefit of Brandywine OP and may be waived in whole or in part, by Brandywine
OP, but only by an instrument in writing signed by Brandywine OP.

         5.2   As to Prentiss' Obligations. Prentiss' obligations hereunder are
subject to the satisfaction of the following conditions precedent:

               (a)  Brandywine OP's Deliveries. Brandywine OP shall have
delivered to or for the benefit of Prentiss, on or before the Closing Date, all
of the documents and payments required of Brandywine OP pursuant to Sections 7.3
and 7.4 hereof.

               (b)  Representations, Warranties and Covenants; Obligations of
Brandywine OP. All of Brandywine OP's representations and warranties made in
this Agreement shall be true and correct in all material respects as of the date
hereof and as of the date of Closing as if then made and Brandywine OP shall
have performed in all material respects all of its covenants and other
obligations under this Agreement.

Each of the conditions contained in this Section are intended for the benefit of
Prentiss and may be waived in whole or in part, by Prentiss, but only by an
instrument in writing signed by Prentiss.

                                  ARTICLE VI.
                              COVENANTS OF PRENTISS

         To induce Brandywine OP to enter into this Agreement and to purchase
the Property, and to pay the Purchase Price therefor, Prentiss covenants and
agrees to the following:

         6.1   Operating Agreements. Prior to the Closing Date, Prentiss shall
not enter into any new management agreement, maintenance or repair contract,
supply contract, lease in which it is lessee or other agreements with respect to
the Property which cannot be terminated on or before the Closing Date, nor shall
Prentiss enter into any agreements modifying the Architect's Agreement in any
material respect, unless (a) any such agreement or modification will not bind
Brandywine OP or the Property after the date of Closing or (b) Prentiss has
obtained Brandywine OP's prior written consent to such agreement or
modification. Prentiss agrees to cancel and terminate effective as of the
Closing Date Prentiss' management agreement, development agreement, and any

                                       20
<PAGE>

other Operating Agreements, if any, other than the Architect's Agreement (which
latter agreement will be assigned to Brandywine OP), to the extent assignable.

         6.2   Warranties and Guaranties. Prentiss shall not before or after
Closing release or modify any Warranties and Guaranties, if any, except with the
prior written consent of Brandywine OP.

         6.3   Insurance. Prior to the Closing Date, Prentiss shall pay all
premiums on, and shall not cancel or voluntarily allow to expire, any of
Prentiss' Insurance Policies unless such policy is replaced, without any lapse
of coverage, by another policy or policies providing coverage at least as
extensive as the policy or policies being replaced. Prentiss hereby indemnifies
and holds Brandywine OP harmless from and against all losses, costs, damages and
expenses resulting from actions involving bodily or personal injury or property
damage in or about any of the Property that occurred prior to the Closing Date,
regardless of when the claim was made, but only to the extent coverage under the
applicable Insurance Policy or Policies is not sufficient and paid, and this
indemnity shall survive the Closing Date.

         6.4   Operation of Property Prior to Closing. Prentiss and Prentiss OP
represent, warrant, covenant and agree with Brandywine OP that, between the date
of this Agreement and the date of Closing:

               (a)  Subject to the restrictions contained herein, Prentiss shall
operate the Property in the same manner in which Prentiss operated the Property
prior to the execution of this Agreement, so as to keep the Property in good
condition, reasonable wear and tear excepted.

               (b)  Prentiss shall maintain its books of account and records in
the usual, regular and ordinary manner, in accordance with sound accounting
principles applied on a basis consistent with the basis used in keeping its
books in prior years.

               (c)  Prentiss shall maintain in full force and effect all
Insurance Policies.

               (d)  Prentiss shall punctually perform and discharge all
obligations and undertakings of Prentiss under the Architect's Agreement and
shall not permit a default by Prentiss to occur thereunder.

               (e)  Prentiss shall use and operate the Property in compliance
with Applicable Laws and the requirements of any Insurance Policy affecting the
Property.

               (f)  Prentiss shall cause to be paid prior to delinquency all ad
valorem and other taxes due and payable with respect to the Property or its
operation.

                                       21
<PAGE>

               (g)  Without the express prior written consent of Brandywine OP,
Prentiss shall not enter into leases of any kind or nature affecting the
Property.

               (h)  Prentiss shall cause all debts and liabilities for labor,
materials, services and equipment incurred in the construction, operation and
development of the Property, including leasehold improvements, to be promptly
paid; provided, all such costs incurred as of the Approved Cost Date shall be
deemed Total Project Costs comprising a portion of the Purchase Price. Any costs
that are incurred or requested for inclusion as Total Project Costs after the
Approved Cost Date, shall only be included as Total Project Costs to the extent
such expenditures are approved by Brandywine OP, which approval shall not be
unreasonably withheld, conditioned or delayed and shall be deemed granted if
Brandywine OP does not respond to such request in three (3) business days,
following the written submission from Prentiss for inclusion of such costs (the
"Approved Total Project Costs").

               (i)  Neither Prentiss nor Prentiss' managing agent shall (1) make
any agreements which shall be binding upon Brandywine OP with respect to the
Property, or (2) reduce, or cause to be reduced any rents or any other revenues
over which Prentiss has operational control.

               (j)  Prentiss shall promptly deliver to Brandywine OP upon
Brandywine OP's request such reports showing the revenue and expenses of the
Property as Prentiss customarily keeps or receives internally for its own use.

               (k)  Prentiss shall not in any manner change, modify, extend,
renew or terminate any Operating Agreement without the express written consent
of Brandywine OP.

               (l)  Prentiss shall promptly advise Brandywine OP of any
litigation, arbitration or administrative hearing concerning or affecting the
Property of which Prentiss obtains actual knowledge.

         6.5   Construction Agreements. Without the express prior written
consent of Brandywine OP, Prentiss shall not enter into any Operating Agreements
affecting the Property.

         6.6   No Marketing. Prentiss shall not market the Property for sale or
enter into discussions or negotiations with potential purchasers of the Property
unless this Agreement has been terminated pursuant to its terms.

The foregoing covenants of Prentiss are for the benefit of Brandywine OP or its
assignee of its rights under this Agreement.

                                       22
<PAGE>

                                  ARTICLE VII.
                                     CLOSING

         7.1   Closing. Provided the Limited Partners do not exercise their
right to purchase the Property pursuant to Section 5.2 of the Partnership
Agreement, the Closing shall occur on the eleventh (11th) day after execution of
this Agreement. As more particularly described below, at the Closing the parties
hereto will meet to (i) execute all of the documents required to be delivered in
connection with the transactions contemplated hereby (the "Closing Documents"),
(ii) deliver the same to Escrow Agent, and (iii) take all other action required
to be taken in respect of the transactions contemplated hereby. The Closing will
occur at the offices of the Escrow Agent. At the Closing, the Title Company
shall update the title to the Property and, provided there has been no change in
the status of title as reflected in the Title Commitment and Survey which has
not been waived by Brandywine OP pursuant to Section 2.4(d) hereof, and Escrow
Agent shall record the Deed, release and date, where appropriate, the Closing
Documents in accordance with the joint instructions of Prentiss and Brandywine
OP and shall send, by wire transfer, all sums, if any, owing to Prentiss or
Brandywine OP hereunder to Prentiss or Brandywine OP, as applicable. At Closing,
the Escrow Agent shall additionally send, by wire transfer to Prentiss all sums
owing to Prentiss hereunder. As provided herein, the parties hereto will agree
upon adjustments and prorations to certain items which cannot be exactly
determined at the Closing and will make the appropriate adjustments with respect
thereto. Possession of the Property shall be delivered to Brandywine OP on the
Closing Date, subject only to Permitted Title Exceptions.

         7.2   Prentiss' Deliveries. At the Closing, Prentiss shall deliver to
Escrow Agent all of the following instruments, each of which shall have been
duly executed and, where applicable, acknowledged and/or sworn on behalf of
Prentiss and shall be dated as of the Closing Date:

               (a)  The certificate required by Section 5.1(b) hereof.

               (b)  The Deed.

               (c)  The Assignment and Assumption Agreement.

               (d)  Such agreements, affidavits or other documents as may be
required by the Title Company to issue the Owner's Title Policy subject only to
the Permitted Title Exceptions and to eliminate such standard exceptions and to
issue the endorsements thereto which are customarily required by institutional
investors purchasing property comparable to the Property.

               (e)  An updated Title Commitment issued by the Title Company,
dated as of the date and time of Closing, subject only to the Permitted Title
Exceptions.

               (f)  The FIRPTA Certificate.

                                       23
<PAGE>

               (g)  All original Warranties and Guaranties, if any, in Prentiss'
possession or reasonably available to Prentiss.

               (h)  Executed originals or copies of all Authorizations as
required hereunder and any other documents or instruments affecting the Property
or the development, ownership and operation thereof.

               (i)  All current real estate and personal property tax bills in
Prentiss' possession or under its control.

               (j)  All books, records, operating reports, appraisal reports,
files and other materials in Prentiss' possession or control which are necessary
in Brandywine OP's reasonable discretion to maintain continuity of operation of
the Property. Brandywine OP covenants to permit Prentiss to photocopy any of the
matters described in this Subparagraph 7.2(k) for a period of three (3) years
following the Closing Date, which covenant of Brandywine OP shall survive for
such three (3) year period.

               (k)  Written notice executed by Prentiss notifying all interested
parties that the Property has been conveyed to Brandywine OP effective as of the
Closing Date and directing that all inquiries and the like be forwarded to
Brandywine OP at the address to be provided by Brandywine OP (or as otherwise
directed by Brandywine OP).

               (l)  A current UCC Report showing no financing statements by
Prentiss as Debtor covering the Property.

               (m)  Possession of the Property subject only to the Permitted
Title Exceptions.

               (n)  Certified copies of a incumbency certificate and resolutions
authorizing the execution by Prentiss of this Agreement and all documents to be
executed by Prentiss on the Closing Date.

               (o)  Estoppel letters from each owners association, if any,
created pursuant to restrictive covenants or deed restrictions affecting the
Real Property certifying that (i) the Real Property complies with such
restrictive covenants or deed restrictions, and (ii) no assessments are due and
owing with respect to the Real Property; provided, Prentiss may execute an
estoppel letter certifying to the foregoing matters for an owners association or
property owner that does not execute any such estoppel letter, which estoppel
letter shall continue in effect unless and until the applicable estoppel letter
is subsequently provided from any such owners association or property owner.

               (p)  Any other document or instrument reasonably requested by
Brandywine OP in connection with the transactions contemplated hereby.

                                       24
<PAGE>

               (q)  Consents and certificates from each party to the Architect's
Agreement, other than Prentiss, in a form reasonably acceptable to Brandywine OP
and each such party.

               (r)  A certificate from Prentiss certifying to the Total Project
Costs paid or accrued by Prentiss as of the Closing Date.

         7.3   Brandywine OP's Deliveries.

               (a)  At the Closing, Brandywine OP shall deliver to Escrow Agent
the balance of the Purchase Price described in Section 2.2(b) hereof. In
addition, Brandywine OP shall pay $200,000.00 to the Limited Partner as provided
in Section 2.2 (c).

               (b)  At the Closing, Brandywine OP shall deliver to Prentiss the
Assignment and Assumption Agreement duly executed by Brandywine OP.

               (c)  At the Closing, Brandywine OP shall deliver to Prentiss any
other document or instrument reasonably requested by Prentiss in connection with
the transactions contemplated hereby.

         7.4   Mutual Deliveries. At the Closing, Brandywine OP and Prentiss
shall mutually execute and deliver each to the other:

               (a)  A final closing statement reflecting the adjustments and
prorations required hereunder and the allocation of income and expenses required
hereby.

               (b)  Such other and further documents, papers and instruments as
may be reasonably required by the parties hereto in connection with the
transactions contemplated hereby or their respective counsel.

         7.5   Closing Costs. Except as is explicitly provided in this
Agreement, each party hereto shall pay its own legal fees and expenses. Prentiss
shall pay for the costs associated with the releases of any deeds of trust,
mortgages and other financing encumbering the Property that Prentiss is to cause
to be released pursuant to this Agreement and for any costs associated with any
corrective instruments. Prentiss shall pay all costs for title searches, tax
certificates and all premiums for the issuance of the Title Policy; all costs of
providing the matters described in Sections 2.4(b) and (d) to Brandywine OP; and
one-half (1/2) of any escrow fees or similar charges of the Escrow Agent.
Brandywine OP shall pay one-half (1/2) of any escrow fees or similar charges of
the Escrow Agent. Prentiss shall pay all prepayment penalties and other costs
and expenses payable in connection with debt which Prentiss is required to
prepay on the Closing Date. Prentiss shall pay all assessments levied or pending
against the Property as of the Closing Date. Transfer taxes and documentary
transfer stamps shall be paid in accordance with the local customs in the States
in which the Property is located. All other expenses incurred by Prentiss or
Brandywine OP with respect to the Closing shall be borne and paid for
exclusively by the party incurring same, without reimbursement, except to the
extent otherwise specifically provided herein.

                                       25
<PAGE>

         7.6   Expense Allocations. All expenses with respect to the Property,
and applicable to the period of time before and after Closing, determined in
accordance with sound accounting principles consistently applied, shall be
allocated between Prentiss and Brandywine OP as provided herein. Prentiss shall
be responsible for all expenses for the period of time up to but not including
the Closing Date, and Brandywine OP shall be responsible for all expenses for
the period of time from, after and including the date of Closing. Such
adjustments shall be shown on the closing statements (with such supporting
documentation as the parties hereto may require being attached as exhibits to
the closing statements) and shall increase or decrease (as the case may be) the
cash amount payable by the parties hereto. Without limiting the generality of
the foregoing, the following items of expense shall be allocated at Closing:

               (a)  Real estate property taxes for the Property for the current
calendar year 2001.

               (b)  Expenses under the Architect's Agreement as long as the
items were listed on Exhibit B or approved for inclusion as a Total Project
Costs by Brandywine OP in accordance with Section 6.4(g).

               (c)  Utility charges (including, but not limited to, charges for
water, sewer and electricity).

               (d)  Municipal or other governmental improvement liens, which
shall be paid by Prentiss at Closing to the extent of the work commenced as of
the Closing Date, and which shall be assumed by Brandywine OP at Closing to the
extent of work that has been authorized, but not physically commenced.

               (e)  All other expenses of the Property.

Prentiss shall pay or cause to be paid all real estate taxes and installments
for special assessments (prorated to the Closing Date) for the Property due and
payable in, or deferred with respect to the years prior to, the year in which
the Closing occurs. All installments for special assessments (prorated to the
Closing Date) pending, levied or due and payable on or prior to the Closing Date
shall be paid by Prentiss on or before the Closing Date. All subdivision and
platting costs and expenses heretofore incurred by Prentiss, including, without
limitation, all subdivision exactions, fees and costs and all dedication of land
for parks and other public uses or payment of fees in lieu thereof, shall be
paid by Prentiss on or prior to the Closing Date.

If accurate allocations cannot be made at Closing because current bills are not
obtainable (as, for example, in the case of utility bills and/or real estate or
personal property taxes), the parties shall allocate such expenses at Closing on
the best available information, subject to adjustment upon receipt of the final

                                       26
<PAGE>

bill or other evidence of the applicable revenue or expense. The obligation to
make the adjustment shall survive the closing of the transaction contemplated by
this Agreement. Any expense incurred by Prentiss or Brandywine OP with respect
to the Property after the Closing Date shall be promptly allocated in the manner
described herein and the parties shall promptly pay or reimburse any amount due.
The proration provisions of this Agreement shall survive the closing of the
transaction contemplated hereby for a period of eighteen (18) months.

         7.7   Costs Associated with Payment of Total Project Costs. Except as
otherwise expressly set forth in this Section 7.7 and Section 6.4 (g) as
approved, all Approved Total Project Costs, not listed on Exhibit B and not
otherwise approved by Brandywine OP in accordance with Section 6.4(g), owing or
which could become due and owing in respect to the Project shall be paid by
Prentiss when due, and Prentiss shall indemnify and hold harmless Brandywine OP
for claims brought against the Property or Brandywine OP arising therefrom,
which indemnity shall survive the Closing Date. Prentiss covenants and agrees to
use commercially reasonable to efforts to obtain and deliver at Closing lien
waivers for Total Project Costs reimbursable by Brandywine OP pursuant to
Section 2.2 hereof. Prentiss covenants and agrees to use commercially reasonable
efforts to pursue all such lien waivers for items reimbursed by Brandywine OP
pursuant to Section 2.2 that are not obtained as of the Closing Date. The
provisions of this Section 7.7 shall survive the Closing Date.

         7.8   Leasing Commissions. Prentiss covenants and agrees to provide the
indemnity set forth in Section 9.2, below for any leasing commissions that are
claimed under Section 5.4.2 of the Partnership Agreement. The foregoing covenant
shall survive Closing.

                                 ARTICLE VIII.
                               GENERAL PROVISIONS

         8.1   Condemnation. In the event of any actual or threatened taking,
pursuant to the power of eminent domain, of all or any portion of the Real
Property, or any proposed sale in lieu thereof, Prentiss shall give written
notice thereof to Brandywine OP promptly after Prentiss learns or receives
notice thereof. If all or any part of the Real Property is, or is to be, so
condemned or sold, Brandywine OP shall have the right to terminate this
Agreement pursuant to Section 9.3 hereof. If Brandywine OP elects not to
terminate this Agreement, all proceeds, awards and other payments arising out of
such condemnation or sale (actual or threatened) shall be paid or assigned, as
applicable, to Brandywine OP at Closing and there shall be no reduction in the
Purchase Price. Prentiss shall not settle or compromise any such proceeding
without Brandywine OP's written consent. If Brandywine OP elects to terminate
this Agreement by giving Prentiss written notice thereof prior to the Closing,
the Deposit shall be promptly returned to Brandywine OP and all rights and
obligations of Prentiss and Brandywine OP hereunder (except those set forth
herein which expressly survive a termination of this Agreement) shall terminate
immediately.

                                       27
<PAGE>

         8.2   Risk of Loss. The risk of any loss or damage to the Property
prior to the recordation of the Deed shall remain upon Prentiss. If any such
loss or damage occurs prior to Closing which exceeds an amount equal to five
percent (5%) of the Purchase Price, Brandywine OP shall have the right to
terminate this Agreement pursuant to Section 9.3 hereof. If Brandywine OP elects
not to terminate this Agreement pursuant to the immediately preceding sentence
or a loss or damage occurs prior to Closing which does not exceed five percent
(5%) of the Purchase Price, all insurance proceeds and rights to proceeds
arising out of such loss or damage, less the reasonable expenses incurred in
collecting such proceeds and, to the extent payable from insurance proceeds,
reasonable expenses incurred in securing the Property following a casualty,
shall be paid or assigned, as applicable, to Brandywine OP at Closing, and
Brandywine OP shall receive as a credit against the Purchase Price in the amount
of any deductibles under the policies of insurance covering such loss or damage
and there shall be no further reduction in the Purchase Price. If Brandywine OP
elects to terminate this Agreement pursuant to this Section 8.2 by giving
Prentiss written notice thereof prior to the Closing, the Deposit shall be
promptly returned to Brandywine OP and all rights and obligations of Prentiss
and Brandywine OP hereunder (except those set forth herein which expressly
survive a termination of this Agreement) shall terminate immediately.

         8.3   Broker. There is no real estate broker involved in this
transaction. Brandywine OP warrants and represents to Prentiss that Brandywine
OP has not dealt with any real estate broker in connection with this
transaction, nor has Brandywine OP been introduced to the Property or to
Prentiss by any real estate broker, and Brandywine OP shall indemnify Prentiss
and hold Prentiss harmless from and against any claims, suits, demands or
liabilities of any kind or nature whatsoever arising on account of the claim of
any other person, firm or corporation to a real estate brokerage commission or a
finder's fee or a financial advisory fee as a result of having dealt with
Brandywine OP, or as a result of having introduced Brandywine OP to Prentiss or
to the Property. In like manner, Prentiss warrants and represents to Brandywine
OP that Prentiss has not dealt with any real estate broker in connection with
this transaction, nor has Prentiss been introduced to Brandywine OP by any real
estate broker, and Prentiss shall indemnify Brandywine OP and save and hold
Brandywine OP harmless from and against any claims, suits, demands or
liabilities of any kind or nature whatsoever arising on account of the claim of
any person, firm or corporation to a real estate brokerage commission or a
finder's fee or a financial advisory fee as a result of having dealt with
Prentiss in connection with this transaction. This provision shall survive any
termination of this Agreement and a closing of the transaction contemplated
hereby.

         8.4   Bulk Sale. It shall be the obligation of Prentiss to comply with
any bulk sale requirements, statutes, laws, ordinances and regulations
promulgated with respect thereto, if any, in the State in which the Property is
located, or in or by any governmental entity having jurisdiction with respect
thereto, and to provide proof of such compliance or proof that no such
compliance is required, to Brandywine OP, at or prior to Closing. In any event,
Prentiss shall indemnify Brandywine OP and save and hold Brandywine OP harmless

                                       28
<PAGE>

from and against any claims, suits, demands, liabilities or obligations of any
kind or nature whatsoever, including all costs of defending same, and reasonable
attorneys' fees paid or incurred in connection therewith, arising out of or
relating to any claim made by any third party or any liability asserted by any
third party that any applicable bulk sales law or like statute has not been
complied with. The provisions of this Section shall survive the Closing of the
transaction contemplated hereby.

                                  ARTICLE IX.
            LIABILITY OF BRANDYWINE OP; INDEMNIFICATION BY PRENTISS;
                           DEFAULT; TERMINATION RIGHTS

         9.1   Liability of Brandywine OP. Except for obligations expressly
assumed or agreed to be assumed by Brandywine OP hereunder, Brandywine OP is not
assuming any obligations of Prentiss or any liability for claims arising out of
any act, omission or occurrence which occurs, accrues or arises prior to the
Closing Date, and Prentiss hereby indemnifies and holds Brandywine OP harmless
from and against any and all claims, costs, penalties, damages, losses,
liabilities and expenses (including reasonable attorneys' fees) that may at any
time be incurred by Brandywine OP as a result of (a) obligations of Prentiss not
expressly assumed or agreed to be assumed by Brandywine OP hereunder, or (b)
acts, omissions or occurrences which occur, accrue or arise prior to the Closing
Date. Brandywine OP hereby indemnifies and holds Prentiss harmless from and
against any and all claims, costs, penalties, damages, losses, liabilities and
expenses (including reasonable attorneys' fees) that may at any time be incurred
by Prentiss as a result of acts, omissions or occurrences relating to the
Property arising and accruing from and after the Closing Date. The provisions of
this Section shall survive the Closing of the transaction contemplated hereby.

         9.2   Indemnification by Prentiss. Prentiss hereby indemnifies and
holds Brandywine OP and Brandywine OP's officers, directors, shareholders,
agents and employees (collectively, the "Indemnified Parties") harmless from and
against any and all claims, costs, penalties, damages, losses, liabilities and
expenses (including reasonable attorneys' fees) that may at any time be incurred
by Brandywine OP, whether incurred before or after Closing, as a result of any
inaccuracy or breach by Prentiss of any of its representations, warranties,
covenants or obligations set forth herein or in any other document delivered by
Prentiss pursuant hereto except for any breach or inaccuracy of any
representation or warranty as to which Prentiss has given Brandywine OP written
notice prior to Closing of the untruth or inaccuracy or of which Brandywine OP
otherwise had actual knowledge prior to the Closing and nevertheless elected to
consummate the Closing; provided, however, the foregoing knowledge limitation on
Prentiss' indemnity shall not apply to any leasing commissions that may be
claimed against Brandywine OP under Section 5.4.2 of the Partnership Agreement
or limit Brandywine OP's remedy described in Section 9.3(a)(ii) hereof or in the
last sentence of Section 9.3 hereof. The provisions of this Section shall
survive the Closing of the transaction contemplated hereby as provided in
Section 10.11 hereof, and shall, following any assignment of this Agreement by

                                       29
<PAGE>

Brandywine OP, continue in favor of the Indemnified Parties of the original
Brandywine OP hereunder as well the Indemnified Parties of any assignee during
said survival period.

         9.3   Default by Prentiss/Failure of Conditions Precedent. If any
condition set forth herein for the benefit of Brandywine OP cannot or will not
be satisfied prior to Closing, or upon the occurrence of any other event that
would entitle Brandywine OP to terminate this Agreement and its obligations
hereunder, and if Prentiss fails to cure any such matter or satisfy that
condition within ten (10) business days after notice thereof from Brandywine OP
(or such other time period as may be explicitly provided for herein), Brandywine
OP, at its option, may elect (a) to terminate this Agreement, in which event (i)
the Deposit, less the Independent Consideration, shall be promptly returned to
Brandywine OP, (ii) if the condition which has not been satisfied is a breach of
a representation, warranty or covenant known by Prentiss to have been inaccurate
or misleading when made, then Prentiss shall be obligated upon demand to
reimburse Brandywine OP for Brandywine OP's actual out-of-pocket inspection,
financing and other costs related to Brandywine OP's entering into this
Agreement, inspecting the Property and preparing for a Closing of the
transaction contemplated hereby, including, without limitation, Brandywine OP's
attorneys' fees incurred in connection with the preparation, negotiation and
execution of this Agreement and in connection with Brandywine OP's due diligence
review, audits and preparation for a Closing up to an aggregate amount equal to
$50,000.00; provided, the foregoing shall not limit or include the sums which
may be payable by Prentiss pursuant to Section 9.6 below, and (iii) all other
rights and obligations of Prentiss and Brandywine OP hereunder (except those set
forth herein which expressly survive a termination of this Agreement) shall
terminate immediately; (b) elect to proceed to Closing; or (c) seek to enforce
Prentiss' obligations hereunder by specific performance. If Brandywine OP elects
to proceed to Closing and there is either a misrepresentation or breach of a
warranty by Prentiss (other than a breach of a representation or warranty of
which Brandywine OP had actual knowledge prior to the Closing and nevertheless
elected to consummate the Closing) or the breach of a covenant by Prentiss or a
failure by Prentiss to perform its obligations hereunder first discovered by
Brandywine OP after the Closing Date, Brandywine OP shall retain all remedies
accruing as a result thereof, including, but not limited to, the remedy of
specific performance of Prentiss' covenants and obligations and the remedy of
the recovery of all reasonable damages resulting from Prentiss' breach of
warranty or covenant. Notwithstanding the foregoing, if the condition which has
not been satisfied is a breach of one or more representations and warranties by
Prentiss in this Agreement, Brandywine OP has elected to proceed to Closing, and
Brandywine OP can reasonably quantify the damage resulting from such breach of
representations and warranties with reasonable support for such calculation of
damages, then (i) if the aggregate damage is no greater than $15,000.00 (the
"First Threshold Level"), then Prentiss shall have no obligation to either cure
such breaches of representations and warranties or pay Brandywine OP at Closing
in the event Brandywine OP elects to close the transaction described in this
Agreement; (ii) if such aggregate damage is greater than the First Threshold
Level but less than $250,000.00, then Prentiss must prior to the Closing Date
either cure such breaches of representations and warranties to the reasonable
satisfaction of Brandywine OP or Prentiss shall pay Brandywine OP at the Closing

                                       30
<PAGE>

an amount equal to the actual damages as reasonably determined by Brandywine OP
as aforesaid, less the First Threshold Level; and (iii) in the event the
aggregate damages resulting from such breaches of representations and warranties
would exceed $250,000.00, then Brandywine OP may either (A) terminate this
Agreement, in which event the Deposit (less the Independent Consideration) shall
be promptly refunded, or (B) Brandywine OP may close the transaction as
described in this Agreement and Brandywine OP shall be paid by Prentiss the
amount of $235,000.00, which amount shall be the maximum aggregate amount
payable by Prentiss, Prentiss OP and/or PPL under the last sentence of Section
9.3 of this Agreement.

         9.4   Indemnification by Brandywine OP. Brandywine OP hereby
indemnifies and holds Prentiss harmless from and against any and all claims,
costs, penalties, damages, losses, liabilities and expenses (including
reasonable attorneys' fees) that may at any time be incurred by Prentiss,
whether incurred before or after Closing, as a result of any inaccuracy or
breach by Brandywine OP of any of its representations, warranties, covenants or
obligations set forth herein or in any other document delivered by Brandywine OP
pursuant hereto except for any breach or inaccuracy of any representation or
warranty as to which Brandywine OP has given Prentiss written notice prior to
Closing of the untruth or inaccuracy or of which Prentiss otherwise had actual
knowledge prior to the Closing and nevertheless elected to consummate the
Closing. The provisions of this Section shall survive the Closing of the
transaction contemplated hereby.

         9.5   Default by Brandywine OP/Failure of Conditions Precedent. If any
condition set forth herein for the benefit of Prentiss (other than a default by
Brandywine OP) cannot or will not be satisfied prior to Closing, and if
Brandywine OP fails to satisfy that condition within ten (10) business days
after notice thereof from Prentiss (or such other time period as may be
explicitly provided for herein), Prentiss may, at its option, elect either (a)
to terminate this Agreement in which event the Deposit shall be promptly
returned to Brandywine OP and the parties hereto shall be released from all
further obligations hereunder except those which expressly survive a termination
of this Agreement, or (b) to waive its right to terminate, and instead, to
proceed to Closing. If, prior to Closing, Brandywine OP defaults in performing
any of its obligations under this Agreement (including its obligation to
purchase the Property), and Brandywine OP fails to cure any such default within
ten (10) business days after notice thereof from Prentiss, then Prentiss' sole
remedy for such default shall be either (i) to terminate this Agreement and
retain the Deposit or (ii) to pursue the remedy of specific performance
compelling Brandywine OP to purchase the Property pursuant to the provisions of
this Agreement.

         9.6   Costs and Attorneys' Fees. In the event of any litigation or
dispute between the parties arising out of or in any way connected with this
Agreement, resulting in any litigation, then the prevailing party in such
litigation shall be entitled to recover its costs of prosecuting and/or
defending same, including, without limitation, reasonable attorneys' fees at
trial and all appellate levels. The provisions of this Section shall survive the
Closing of the transaction contemplated hereby.

                                       31
<PAGE>

         9.7   Limitation of Liability. Notwithstanding anything herein to the
contrary, except in the case of fraud by either party, the liability of each
party hereto resulting from the breach or default by either party shall be
limited to actual damages incurred by the injured party and except in the case
of fraud by either party, the parties hereto hereby waive their rights to
recover from the other party consequential, punitive, exemplary, and speculative
damages. The provisions of this Section 9.7 shall survive the Closing of the
transaction contemplated hereby.

                                   ARTICLE X.
                            MISCELLANEOUS PROVISIONS

         10.1  Completeness; Modification. This Agreement constitutes the entire
agreement between the parties hereto with respect to the transactions
contemplated hereby and supersedes all prior discussions, understandings,
agreements and negotiations between the parties hereto. This Agreement may be
modified only by a written instrument duly executed by the parties hereto. Any
waiver of rights under this Agreement shall be effective only if in writing and
duly executed and delivered by the party against whom such waiver is asserted.

         10.2  Assignments. Brandywine OP may assign its rights hereunder
without the consent of Prentiss to any affiliate of Brandywine OP, in which
event, except as otherwise specified herein, such assignee shall be the
"Brandywine OP" hereunder; however, any such assignment shall not relieve the
original Brandywine OP of its obligations under this Agreement, including
specifically the obligation to close the purchase of the Property in accordance
with this Agreement as though there were no assignment.

         10.3  Successors and Assigns. This Agreement shall bind and inure to
the benefit of the parties hereto and their respective successors and assigns.

         10.4 Days. If any action is required to be performed, or if any notice,
consent or other communication is given, on a day that is a Saturday or Sunday
or a legal holiday in the jurisdiction in which the action is required to be
performed or in which is located the intended recipient of such notice, consent
or other communication, such performance shall be deemed to be required, and
such notice, consent or other communication shall be deemed to be given, on the
first business day following such Saturday, Sunday or legal holiday. Unless
otherwise specified herein, all references herein to a "day" or "days" shall
refer to calendar days and not business days.

         10.5  Governing Law. This Agreement and all documents referred to
herein shall be governed by and construed and interpreted in accordance with the
laws of the State of Delaware.

                                       32
<PAGE>

         10.6  Counterparts. To facilitate execution, this Agreement may be
executed in as many counterparts as may be required. It shall not be necessary
that the signature on behalf of both parties hereto appear on each counterpart
hereof. All counterparts hereof shall collectively constitute a single
agreement.

         10.7  Severability. If any term, covenant or condition of this
Agreement, or the application thereof to any person or circumstance, shall to
any extent be invalid or unenforceable, the remainder of this Agreement, or the
application of such term, covenant or condition to other persons or
circumstances, shall not be affected thereby, and each term, covenant or
condition of this Agreement shall be valid and enforceable to the fullest extent
permitted by law.

         10.8  Notices. All notices, requests, demands and other communications
hereunder shall be in writing and shall be delivered by hand, transmitted by
facsimile transmission, sent prepaid by Federal Express (or a comparable
overnight delivery service) or sent by the United States mail, certified,
postage prepaid, return receipt requested, at the addresses and with such copies
as designated below. Any notice, request, demand or other communication
delivered or sent in the manner aforesaid shall be deemed given or made (as the
case may be) when actually delivered to the intended recipient.

         If to Brandywine OP: c/o Brandywine Realty Trust
                              14 Campus Boulevard, Suite 100
                              Newtown Square, PA  19073-3780
                              Attn: Brad A. Molotsky, General Counsel
                              Fax No.: 610-325-4628

         If to Prentiss:      c/o Prentiss Properties Acquisition Partners, L.P.
                              3860 West Northwest Highway, Suite 400
                              Dallas, Texas  75220
                              Attn.: J. Kevan Dilbeck, General Counsel
                              Fax No.: (214) 350-2409

         With a copy to:      Akin, Gump, Strauss, Hauer & Feld, L.L.P.
                              1700 Pacific Avenue, Suite 4100
                              Dallas, Texas  75201-4675
                              Attn.:  Randall M. Ratner, P.C.
                              Fax No.:  (214) 969-4343

         If to Escrow Agent:  Chicago Title Insurance Company
                              2001 Bryan Street, Suite 1700
                              Dallas, Texas  75201
                              Attn.:  Ellen Schwab
                              Fax No.:  (214) 965-1629

                                       33
<PAGE>

or to such other address as the intended recipient may have specified in a
notice to the other party. Any party hereto may change its address or designate
different or other persons or entities to receive copies by notifying the other
party and Escrow Agent in a manner described in this Section.

         10.9  Escrow Agent. Escrow Agent referred to in the definition thereof
contained in Section 1.1 hereof has agreed to act as such for the convenience of
the parties without fee or other charges for such services as Escrow Agent.
Escrow Agent shall not be liable: (a) to any of the parties for any act or
omission to act except for its own willful misconduct; (b) for any legal effect,
insufficiency, or undesirability of any instrument deposited with or delivered
by Escrow Agent or exchanged by the parties hereunder, whether or not Escrow
Agent prepared such instrument; (c) for any loss or impairment of funds that
have been deposited in escrow while those funds are in the course of collection,
or while those funds are on deposit in a financial institution, if such loss or
impairment results from the failure, insolvency or suspension of a financial
institution; (d) for the expiration of any time limit or other consequence of
delay, unless a properly executed written instruction, accepted by Escrow Agent,
has instructed Escrow Agent to comply with said time limit; or (e) for the
default, error, action or omission of either party to the escrow. Escrow Agent,
in its capacity as escrow agent, shall be entitled to rely on any document or
paper received by it, believed by such Escrow Agent, in good faith, to be bona
fide and genuine. In the event of any dispute as to the disposition of the
Deposit or any other monies held in escrow, or of any documents held in escrow,
Escrow Agent may, if such Escrow Agent so elects, interplead the matter by
filing an interpleader action in a court of general jurisdiction in the county
or circuit where the Real Property is located (to the jurisdiction of which both
parties do hereby consent), and pay into the registry of the court the Deposit,
or deposit any such documents with respect to which there is a dispute in the
Registry of such court, whereupon such Escrow Agent shall be relieved and
released from any further liability as Escrow Agent hereunder. Escrow Agent
shall not be liable for Escrow Agent's compliance with any legal process,
subpoena, writ, order, judgment and decree of any court, whether issued with or
without jurisdiction, and whether or not subsequently vacated, modified, set
aside or reversed.

         10.10 Incorporation by Reference. All of the exhibits attached hereto
are by this reference incorporated herein and made a part hereof.

         10.11 Survival. All of the representations, warranties, covenants and
agreements of Prentiss and Brandywine OP made in, or pursuant to, this Agreement
shall survive Closing through the period ending twelve (12) months thereafter
and shall not merge into the Deed or any other document or instrument executed

                                       34
<PAGE>

and delivered in connection herewith; provided, the covenants in the last
sentence of Section 2.4(b) and Section 7.6 shall survive for the time periods
described in such Sections, and the covenants in Section 7.7 and the indemnities
in this Agreement shall have an unlimited survival period. In the event a claim
for indemnity is asserted in good faith prior to the expiration of the
applicable survival period, the claim may be asserted and the indemnity shall
continue notwithstanding the expiration of the survival period.

         10.12 Further Assurances. Prentiss and Brandywine OP each covenant and
agree to sign, execute and deliver, or cause to be signed, executed and
delivered, and to do or make, or cause to be done or made, upon the written
request of the other party, any and all agreements, instruments, papers, deeds,
acts or things, supplemental, confirmatory or otherwise, as may be reasonably
required by either party hereto for the purpose of or in connection with
consummating the transactions described herein. Prentiss agrees to promptly
correct any defect, error or omission which may be discovered in the contents of
this Agreement or in any of the Exhibits or Schedules hereto.

         10.13 No Partnership. This Agreement does not and shall not be
construed to create a partnership, joint venture or any other relationship
between the parties hereto except the relationship of Prentiss and Brandywine OP
specifically established hereby.

         10.14 Time of Essence. Time is of the essence with respect to every
provision hereof.

         10.15 Signatory Exculpation. The signatory(ies) for Prentiss and
Brandywine OP are executing this Agreement in his/their capacity as
representative of Prentiss and Brandywine OP, respectively, and not individually
and, therefore, shall have no personal or individual liability of any kind in
connection with this Agreement and the transactions contemplated by it. No
recourse shall be had for any obligation of Prentiss or Brandywine OP under this
Agreement or under any document executed in connection herewith or pursuant
hereto, or for any claim based thereon or otherwise in respect thereof, against
any past, present or future trustee, shareholder, officer or employee of
Brandywine Realty Trust, Prentiss Properties Trust, Prentiss or Brandywine OP,
whether by virtue of any statute or rule of law, or by the enforcement of any
assessment or penalty or otherwise, all such liability being expressly waived
and released by the parties hereto and all parties claiming by, through or under
them.

         10.16 Rules of Construction. The following rules shall apply to the
construction and interpretation of this Agreement:

               (a)  Singular words shall connote the plural number as well as
the singular and vice versa, and the masculine shall include the feminine and
the neuter.

               (b)  All references herein to particular articles, sections,
subsections, clauses or exhibits are references to articles, sections,
subsections, clauses or exhibits of this Agreement.

                                       35
<PAGE>

               (c)  The table of contents and headings contained herein are
solely for convenience of reference and shall not constitute a part of this
Agreement nor shall they affect its meaning, construction or effect.

               (d)  Each party hereto and its counsel have reviewed and revised
(or requested revisions of) this Agreement and have participated in the
preparation of this Agreement, and therefore any usual rules of construction
requiring that ambiguities are to be resolved against a particular party shall
not be applicable in the construction and interpretation of this Agreement or
any exhibits hereto.

               (e)  As used herein, the term or phrases "Effective Date," "date
of this Agreement" or "date hereof" shall mean the first date Escrow Agent is in
receipt of this Agreement executed by Prentiss and Brandywine OP.

         10.17 Like-Kind Exchange. Prentiss agrees to cooperate reasonably with
Brandywine OP in effecting an exchange transaction which includes the Property,
pursuant to Section 1031 of the United States Internal Revenue Code, provided
that any such exchange transaction, and the related documentation, shall: (a) be
at the sole cost and expense of Brandywine OP; (b) not require Prentiss to
execute any contract, make any commitment, or incur any obligations, contingent
or otherwise, to third parties; (c) not delay the Closing; (d) not include
Prentiss becoming involved in a transaction with a third party; and (e) not
otherwise be contrary to or inconsistent with the terms of this Agreement. In
preparation for any such exchange transaction, Brandywine OP shall be permitted
to transfer the Property to an affiliate of Brandywine OP prior to Closing.

         10.18 SEC Reporting (8-K) Requirements. For the period of time
commencing on the date hereof and continuing through the second anniversary of
the Closing Date, and without limitation of other document production otherwise
required of Prentiss hereunder, Prentiss shall, from time to time, upon
reasonable advance written notice from Brandywine OP, provide Brandywine OP and
its representatives, with access to all financial and other information
pertaining to the period of Prentiss' ownership and operation of the Property,
which information is relevant and reasonably necessary, in the opinion of
outside, third party accountants (the "Accountants") for Brandywine OP, to
enable Brandywine OP and its Accountants to prepare financial statements in
compliance with any or all of (a) Rule 3-05 or 3-14 of Regulation S-X of the
Securities and Exchange Commission (the "Commission"), as applicable; (b) any
other rule issued by the Commission and applicable to Brandywine OP or
Brandywine Realty Trust ("Brandywine"); and (c) any registration statement,
report or disclosure statement filed with the Commission by Brandywine; and a
representation letter, signed by the individual(s) responsible for Prentiss'
financial reporting, as prescribed by generally accepted auditing standards
promulgated by the Auditing Standards Division of the American Institute of
Certified Public Accountants, which representation letter may be required by the
Accountants in order to render an opinion concerning Brandywine OP's or
Brandywine's financial statements.

                                       36
<PAGE>

         IN WITNESS WHEREOF, Prentiss and Brandywine OP have caused this
Agreement to be executed in their names by their respective duly authorized
representatives.

                                BRANDYWINE OP:

                                BRANDYWINE OPERATING PARTNERSHIP, L.P.,
                                a Delaware limited partnership

                                By: Brandywine Realty Trust, its general partner

                                    By: /s/ Gerard H. Sweeney
                                        ----------------------------------------
                                    Title: President and Chief Executive Officer
                                           -------------------------------------

                                    Date of Execution: March 14, 2001

                                PRENTISS:

                                935 FIRST AVENUE ASSOCIATES,
                                a Pennsylvania limited partnership

                                By: Prentiss Properties Acquisition Partners,
                                    L.P., a Delaware limited partnership, its
                                    general partner

                                By: Prentiss Properties I, Inc., a Delaware
                                    corporation, its general partner

                                    By: /s/ Thomas F. August
                                        ----------------------------------------
                                    Title: President and Chief Executive Officer
                                           -------------------------------------

                                    Date of Execution: March 14, 2001

                                       37
<PAGE>

                             RECEIPT OF ESCROW AGENT

         Chicago Title Insurance Company, as Escrow Agent, acknowledges receipt
of the sum of $5,000,050.00 by check or by wire transfer, from Brandywine OP as
described in Section 2.3 of the foregoing Agreement of Purchase and Sale, said
check or wire transfer to be held pursuant to the terms and provisions of said
Agreement.

         DATED this _____ day of __________, 2001.

                                    CHICAGO TITLE INSURANCE COMPANY

                                    By:_________________________________________

                                    Name:_______________________________________

                                    Title:______________________________________

                                       38

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