Document:

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                                                                   EXHIBIT 10.23

              THIRD AMENDED AND RESTATED REVOLVING CREDIT AGREEMENT

                                      among

                      BOSTON PROPERTIES LIMITED PARTNERSHIP

                                       and

           OTHER BORROWERS WHICH MAY BECOME PARTIES TO THIS AGREEMENT

                                       and

                               FLEET NATIONAL BANK
                              BANK OF AMERICA, N.A.
                COMMERZBANK AG NEW YORK AND GRAND CAYMAN BRANCHES
                               JPMORGAN CHASE BANK
                      WELLS FARGO BANK NATIONAL ASSOCIATION
                         PNC BANK, NATIONAL ASSOCIATION
                              THE BANK OF NEW YORK
                          CITICORP NORTH AMERICA, INC.
               BAYERISCHE HYPO-UND VEREINSBANK AG, NEW YORK BRANCH
                      DEUTSCHE BANK TRUST COMPANY AMERICAS
                                  KEYBANK, N.A.
              DRESDNER BANK AG, NEW YORK AND GRAND CAYMAN BRANCHES
                                  CITIZENS BANK

                                       and

        OTHER BANKS WHICH MAY BECOME PARTIES TO THIS AGREEMENT, AS BANKS

                                       and

                              FLEET NATIONAL BANK,
                        AS MANAGING ADMINISTRATIVE AGENT

                             BANK OF AMERICA, N.A.,
                              AS SYNDICATION AGENT

                                       and

                COMMERZBANK AG NEW YORK AND GRAND CAYMAN BRANCHES
                               JPMORGAN CHASE BANK
                                       and
                     WELLS FARGO BANK NATIONAL ASSOCIATION,
                           AS CO-DOCUMENTATION AGENTS

                                      with

           FLEET SECURITIES, INC. AND BANC OF AMERICA SECURITIES LLC,
              ACTING AS JOINT LEAD ARRANGERS AND JOINT BOOKRUNNERS

                          Dated as of January 17, 2003

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                                TABLE OF CONTENTS

<Table>
<Caption>
Section                                                                              Page
-------                                                                              ----
<S>                                                                                    <C>
Section 1.    DEFINITIONS AND RULES OF INTERPRETATION                                   2

   Section 1.1.     Definitions                                                         2

   Section 1.2.     Rules of Interpretation                                            31

Section 2.    THE REVOLVING CREDIT FACILITY                                            31

   Section 2.1.     Commitment to Lend                                                 31

   Section 2.2.     The Revolving Credit Notes                                         33

   Section 2.3.     Interest on Revolving Credit Loans; Fees                           33

   Section 2.4.     Requests for Revolving Credit Loans                                34

   Section 2.5.     Conversion Options                                                 36

   Section 2.6.     Funds for Revolving Credit Loans                                   37

   Section 2.7.     Reduction of Commitment                                            38

   Section 2.8.     Swingline Loans                                                    38

   Section 2.9.     Bid Rate Advances                                                  41

   Section 2.10.    Increases in Total Commitment                                      45

   Section 2.11.    Extension of Revolving Credit Maturity Date                        46

Section 3.    LETTERS OF CREDIT                                                        46

   Section 3.1.     Letter of Credit Commitments                                       46

   Section 3.1.1.   Commitment to Issue Letters of Credit                              46

   Section 3.1.2.   Letter of Credit Applications                                      46
</Table>

                                       -i-
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<Table>
<S>                                                                                    <C>
   Section 3.1.3.   Terms of Letters of Credit                                         47

   Section 3.1.4.   Obligations of Banks with respect to Letters of Credit             47

   Section 3.1.5.   Fronting Bank                                                      47

   Section 3.2.     Reimbursement Obligation of the Borrower                           47

   Section 3.3.     Letter of Credit Payments; Funding of a Loan                       48

   Section 3.4.     Obligations Absolute                                               49

   Section 3.5.     Reliance by Issuer                                                 49

   Section 3.6.     Letter of Credit Fee                                               50

Section 4.    REPAYMENT OF THE REVOLVING CREDIT LOANS                                  50

   Section 4.1.     Maturity                                                           50

   Section 4.2.     Optional Repayments of Revolving Credit Loans                      50

   Section 4.3.     Mandatory Repayment of Loans                                       51

Section 5.    CERTAIN GENERAL PROVISIONS                                               51

   Section 5.1.     Funds for Payments                                                 51

   Section 5.2.     Computations                                                       52

   Section 5.3.     Inability to Determine Eurodollar Rate                             52

   Section 5.4.     Illegality                                                         52

   Section 5.5.     Additional Costs, Etc.                                             53

   Section 5.6.     Capital Adequacy                                                   54

   Section 5.7.     Certificate; Limitations                                           55

   Section 5.8.     Indemnity                                                          55

   Section 5.9.     Interest on Overdue Amounts                                        55

Section 6.    RECOURSE OBLIGATIONS                                                     56
</Table>

                                      -ii-
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<Table>
<S>                                                                                    <C>
Section 7.    REPRESENTATIONS AND WARRANTIES                                           56

   Section 7.1.     Authority, Etc.                                                    56

   Section 7.2.     Governmental Approvals                                             58

   Section 7.3.     Title to Properties; Leases                                        58

   Section 7.4.     Financial Statements                                               59

   Section 7.5.     No Material Changes, Etc.                                          59

   Section 7.6.     Franchises, Patents, Copyrights, Etc.                              59

   Section 7.7.     Litigation                                                         60

   Section 7.8.     No Materially Adverse Contracts, Etc.                              60

   Section 7.9.     Compliance With Other Instruments, Laws, Etc.                      60

   Section 7.10.    Tax Status                                                         60

   Section 7.11     No Event of Default                                                61

   Section 7.12.    Investment Company Acts                                            61

   Section 7.13.    Absence of UCC Financing Statements, Etc.                          61

   Section 7.14.    Absence of Liens                                                   61

   Section 7.15.    Certain Transactions                                               61

   Section 7.16.    Employee Benefit Plans; Multiemployer Plans; Guaranteed
Pension Plans                                                                          61

   Section 7.17.    Regulations U and X                                                61

   Section 7.18.    Environmental Compliance                                           61

   Section 7.19.    Subsidiaries                                                       63

   Section 7.20.    Loan Documents                                                     63

   Section 7.21.    REIT Status                                                        64

Section 8.    AFFIRMATIVE COVENANTS OF THE BORROWER AND BPI                            64
</Table>

                                      -iii-
<Page>

<Table>
<S>                                                                                    <C>
   Section 8.1.     Punctual Payment                                                   64

   Section 8.2.     Maintenance of Office                                              64

   Section 8.3.     Records and Accounts                                               64

   Section 8.4.     Financial Statements, Certificates and Information                 64

   Section 8.5.     Notices                                                            67

   Section 8.6.     Existence of Borrower;  Maintenance of Properties                  69

   Section 8.7.     Existence of BPI; Maintenance of REIT Status of BPI;
Maintenance of Properties                                                              70

   Section 8.8.     Insurance                                                          70

   Section 8.9.     Taxes                                                              71

   Section 8.10.    Inspection of Properties and Books                                 71

   Section 8.11.    Compliance with Laws, Contracts, Licenses, and Permits             73

   Section 8.12.    Use of Proceeds                                                    73

   Section 8.13.    Addition of Borrowing Base Property                                74

   Section 8.14.    Additional Borrowers; Solvency of Borrowers; Removal of
                    Borrowers                                                          74

   Section 8.15.    Further Assurances                                                 75

   Section 8.16.    Interest Rate Protection                                           75

   Section 8.17.    Environmental Indemnification                                      75

   Section 8.18.    Response Actions                                                   76

   Section 8.19.    Environmental Assessments                                          76

   Section 8.20.    Employee Benefit Plans                                             77

   Section 8.21.    No Amendments to Certain Documents                                 77

Section 9.    CERTAIN NEGATIVE COVENANTS OF THE BORROWER AND BPI                       78

   Section 9.1.     Restrictions on Liabilities                                        78
</Table>

                                      -iv-
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<Table>
<S>                                                                                    <C>
   Section 9.2.     Restrictions on Liens, Etc.                                        79

   Section 9.3.     Restrictions on Investments                                        81

   Section 9.4.     Merger, Consolidation and Disposition of Assets; Assets of BPI     83

   Section 9.5.     Compliance with Environmental Laws                                 84

   Section 9.6.     Distributions                                                      84

   Section 9.7.     Hotel Properties                                                   84

Section 10.   FINANCIAL COVENANTS; COVENANTS REGARDING BORROWING BASE PROPERTIES       85

   Section 10.1.    Consolidated Total Indebtedness                                    85

   Section 10.2.    Secured Consolidated Total Indebtedness                            85

   Section 10.3.    Debt Service Coverage                                              85

   Section 10.4.    Reserved                                                           85

   Section 10.5.    Net Worth                                                          86

   Section 10.6.    Borrowing Base Properties                                          86

   Section 10.7.    Borrowing Base Debt Service Coverage Ratio                         87

Section 11.   [RESERVED.]                                                              87

Section 12.   CONDITIONS TO THE FIRST ADVANCE                                          87

   Section 12.1.    Loan Documents                                                     87

   Section 12.2.    Certified Copies of Organization Documents                         87

   Section 12.3.    By-laws; Resolutions                                               88

   Section 12.4.    Incumbency Certificate: Authorized Signers                         88

   Section 12.5.    Title Policies                                                     88

   Section 12.6.    Certificates of Insurance                                          88
</Table>

                                       -v-
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<Table>
<S>                                                                                    <C>
   Section 12.7.    Hazardous Substance Assessments                                    88

   Section 12.8.    Opinion of Counsel Concerning Organization and Loan Documents      88

Section 12.9. [RESERVED.]                                                              89

   Section 12.10.   Structural Condition Assurances                                    89

   Section 12.11.   Financial Analysis of Borrowing Base Properties                    89

   Section 12.12.   Inspection of Borrowing Base Properties                            89

   Section 12.13.   Certifications from Government Officials                           89

   Section 12.14.   [Reserved.]                                                        89

   Section 12.15.   Proceedings and Documents                                          89

   Section 12.16.   Fees                                                               90

   Section 12.17.   Closing Certificate; Compliance Certificate                        90

   Section 12.18.   Partnership Documents                                              90

   Section 12.19.   Release Documents                                                  90

Section 13.   CONDITIONS TO ALL BORROWINGS                                             90

   Section 13.1.    Representations True; No Event of Default; Compliance Certificate  90

   Section 13.2.    No Legal Impediment                                                91

   Section 13.3.    Governmental Regulation                                            91

Section 14.   EVENTS OF DEFAULT; ACCELERATION; ETC.                                    91

   Section 14.1.    Events of Default and Acceleration                                 91

   Section 14.2.    Termination of Commitments                                         96

   Section 14.3.    Remedies                                                           96

Section 15.   SETOFF                                                                   97
</Table>

                                      -vi-
<Page>

<Table>
<S>                                                                                   <C>
Section 16.   THE AGENT                                                                97

   Section 16.1.    Authorization                                                      97

   Section 16.2.    Employees and Agents                                               97

   Section 16.3.    No Liability                                                       97

   Section 16.4.    No Representations                                                 98

   Section 16.5.    Payments                                                           98

   Section 16.6.    Holders of Revolving Credit Notes                                  99

   Section 16.7.    Indemnity                                                          99

   Section 16.8.    Agent as Bank                                                      99

   Section 16.9.    Notification of Defaults and Events of Default                     99

   Section 16.10.   Duties in the Case of Enforcement                                  99

   Section 16.11.   Successor Agent                                                   100

   Section 16.12.   Notices                                                           101

Section 17.   EXPENSES                                                                101

Section 18.   INDEMNIFICATION                                                         102

Section 19.   SURVIVAL OF COVENANTS, ETC.                                             102

Section 20.   ASSIGNMENT; PARTICIPATIONS; ETC.                                        103

   Section 20.1.    Conditions to Assignment by Banks.                                103

   Section 20.2.    Certain Representations and Warranties; Limitations; Covenants    104

   Section 20.3.    Register                                                          105

   Section 20.4.    New Notes                                                         105

   Section 20.5.    Participations                                                    105

   Section 20.6.    Pledge by Lender                                                  106
</Table>

                                      -vii-
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<Table>
<S>                                                                                   <C>
   Section 20.7.    No Assignment by Borrower                                         106

   Section 20.8.    Disclosure                                                        106

   Section 20.9.    Syndication                                                       106

Section 21.   NOTICES, ETC.                                                           106

Section 22.   BPLP AS AGENT FOR THE BORROWER                                          107

Section 23.   GOVERNING LAW; CONSENT TO JURISDICTION AND SERVICE                      107

Section 24.   HEADINGS                                                                108

Section 25.   COUNTERPARTS                                                            108

Section 26.   ENTIRE AGREEMENT, ETC.                                                  108

Section 27.   WAIVER OF JURY TRIAL AND CERTAIN DAMAGE CLAIMS                          108

Section 28.   CONSENTS, AMENDMENTS, WAIVERS, ETC.                                     109

Section 29.   SEVERABILITY                                                            110

Section 30.   INTEREST RATE LIMITATION                                                111
</Table>

                                     -viii-
<Page>

        EXHIBITS TO THIRD AMENDED AND RESTATED REVOLVING CREDIT AGREEMENT

A       Form of Revolving Credit Note
A-1     Form of Swingline Note
B       Form of Loan Request
C       Form of Compliance Certificate
D       Forms of Competitive Bid Documents
E       Form of Closing Certificate
F       Form of Assignment and Assumption Agreement
G       Form of Joinder Agreement

                                      -ix-
<Page>

       SCHEDULES TO THIRD AMENDED AND RESTATED REVOLVING CREDIT AGREEMENT

Schedule 1          Borrower
Schedule 2          Banks
Schedule 3          Borrowing Base Properties
Schedule 4          CBD Properties
Schedule 7.1(b)     Preferred Creditor Equity
Schedule 7.7        Litigation
Schedule 7.16       Employee Benefit Plans
Schedule 7.19       Subsidiaries
Schedule 8.5(b)     Environmental Events
Schedule 9.1(e)     BPI Liabilities
Schedule 9.3        Investments

                                       -x-
<Page>

                           THIRD AMENDED AND RESTATED
                           REVOLVING CREDIT AGREEMENT

    This THIRD AMENDED AND RESTATED REVOLVING CREDIT AGREEMENT is made as of the
17th day of January, 2003, by and among BOSTON PROPERTIES LIMITED PARTNERSHIP, a
Delaware limited partnership ("BPLP") and the Wholly-owned Subsidiaries (defined
below) which are listed on SCHEDULE 1 hereto (as such Schedule 1 may be amended
from time to time) (BPLP and any such Wholly-owned Subsidiary being hereinafter
referred to collectively as the "Borrower" unless referred to in their
individual capacities), having their principal place of business at 800 Boylston
Street, Boston, Massachusetts 02199; FLEET NATIONAL BANK ("Fleet"), having its
principal place of business at One Federal Street, Boston, Massachusetts 02109
and the other lending institutions listed on SCHEDULE 2 hereto or which may
become parties hereto pursuant to Section 20 (individually, a "Bank" and
collectively, the "Banks"); FLEET, as managing administrative agent for itself
and each other Bank; BANK OF AMERICA, N.A., as Syndication Agent, and
COMMERZBANK AG NEW YORK AND GRAND CAYMAN BRANCHES, JPMORGAN CHASE BANK and WELLS
FARGO BANK NATIONAL ASSOCIATION, as Co-Documentation Agents; and FLEET
SECURITIES, INC. and BANC OF AMERICA SECURITIES LLC, as Joint Lead Arrangers and
Joint Bookrunners.

                                    RECITALS

    A.    The Borrower, certain of its Subsidiaries and BankBoston, N.A. entered
into that certain Revolving Credit Agreement dated as of June 23, 1997 (as
amended, the "Initial Credit Agreement") and acted as agent thereunder.

    B.    The Initial Credit Agreement (i) was amended and restated in its
entirety as of March 31, 1998 pursuant to the Amended and Restated Revolving
Credit Agreement among the Borrower, certain of its Subsidiaries, BankBoston,
N.A., individually and as managing administrative agent, and certain other
financial institutions, including Fleet, and (ii) was further amended and
restated in its entirety again as of March 31, 2000 pursuant to the Second
Amended and Restated Revolving Credit Agreement among the Borrower, certain of
its Subsidiaries, Fleet (as successor to BankBoston, N.A.), individually and as
managing administrative agent, and certain other financial institutions (such
Second Amended and Restated Revolving Credit Agreement, as amended, the
"Existing Credit Agreement").

    C.    Effective March 1, 2000, Fleet National Bank was merged into
BankBoston, N.A. and simultaneously therewith, BankBoston, N.A. changed its name
to Fleet National Bank.

                                       -1-
<Page>

    D.    The Borrower, Fleet and the other lenders and agents under the
Existing Credit Agreement desire to amend the Existing Credit Agreement in
certain respects as set forth herein (including, without limitation, to reflect
the withdrawal of certain of the Banks thereunder).

    E.    The Borrower is primarily engaged in the business of owning,
purchasing, developing, constructing, renovating and operating office and
industrial buildings and hotels in the United States.

    F.    Boston Properties, Inc., a Delaware corporation ("BPI"), is the sole
general partner of BPLP, holds in excess of 65% of the partnership interests in
BPLP as of the date of this Agreement, and is qualified to elect REIT status for
income tax purposes.

    G.    The Borrower has requested the Banks, and the Banks have agreed, to
amend and restate the existing unsecured revolving credit facility for use by
the Borrower pursuant to the terms and conditions hereof.

    NOW, THEREFORE, in consideration of the mutual covenants and agreements
herein contained, the parties hereto agree that the Existing Credit Agreement
shall be amended and restated effective as of January 17, 2003, to read as
follows:

    Section 1.     DEFINITIONS AND RULES OF INTERPRETATION.

    Section 1.1.   Definitions. The following terms shall have the meanings set
forth in this Section 1 or elsewhere in the provisions of this Agreement
referred to below:

    111 HUNTINGTON AVENUE. The property located at 111 Huntington Avenue,
Boston, Massachusetts. The Agent hereby acknowledges that, as of the date
hereof, 111 Huntington Avenue is a CBD Property.

    399 PARK AVENUE. The property located at 399 Park Avenue, New York, New
York. The Agent hereby acknowledges that, as of the date hereof, 399 Park Avenue
is a CBD Property.

    ABSOLUTE RATE AUCTION. With respect to a request by the Borrower for a Bid
Rate Advance, a solicitation in which the Borrower specifies in the Bid Rate
Advance Borrowing Notice that the rates of interest to be offered by the Banks
shall be absolute rates per annum.

    ACCOUNTANTS. In each case, independent certified public accountants
reasonably acceptable to the Majority Banks. The Banks hereby acknowledge that
the Accountants may include PriceWaterhouse Coopers LLP and any other so-called
"big-four" accounting firm.

                                       -2-
<Page>

    ACCOUNTS PAYABLE. See definition of "Consolidated Total Indebtedness".

    ACCOUNTS RECEIVABLE. Collectively, without double-counting, each of the
accounts receivable of the Borrower and its Subsidiaries which (i) arose in the
ordinary course of business of the Borrower or such Subsidiary, (ii) would be
classified under GAAP as a current asset on the balance sheet of the Borrower or
such Subsidiary and is not more than 60 days past due under the original terms,
and (iii) to the knowledge of the Borrower or such Subsidiary, is the valid and
binding obligation of the account debtor.

    ADVANCE RATE. See definition of "Eligible Amount".

    AFFILIATE. With reference to any Person, (i) any director or executive
officer of that Person, (ii) any other Person controlling, controlled by or
under direct or indirect common control of that Person, (iii) any other Person
directly or indirectly holding 10% or more of any class of the capital stock or
other equity interests (including options, warrants, convertible securities and
similar rights) of that Person and (iv) any other Person 10% or more of any
class of whose capital stock or other equity interests (including options,
warrants, convertible securities and similar rights) is held directly or
indirectly by that Person.

    AGENT. Fleet acting as managing administrative agent for the Banks, or any
successor agent, as permitted by Section 16.

    AGENT'S HEAD OFFICE. The Agent's office located at One Federal Street,
Boston, Massachusetts 02109, or at such other location as the Agent may
designate from time to time, or the office of any successor Agent permitted
under Section 16, PROVIDED such office (which need not be such successor Agent's
head office) is located in Boston, Massachusetts.

    AGREEMENT. This Third Amended and Restated Revolving Credit Agreement,
including the SCHEDULES and Exhibits hereto, as the same may be from time to
time amended and in effect.

    AGREEMENT OF LIMITED PARTNERSHIP OF BPLP. The Amended and Restated Agreement
of Limited Partnership of BPLP, dated June 23, 1997, as amended, among BPI and
the limited partners named therein, as amended through the date hereof and as
the same may be further amended from time to time as permitted by Section 8.21.

    ANNUALIZED BORROWING BASE PROPERTIES CAPITAL EXPENDITURES. (i) With respect
to any Real Estate Assets which are Borrowing Base Properties, other than hotel
properties, for any rolling four (4) calendar quarters, determined as of the
last day of a calendar quarter, an amount equal to $.25 MULTIPLIED BY the total
number of square feet of the Real Estate Assets, which are Borrowing Base
Properties, other than hotel properties on the last day of such calendar
quarter; (ii) with respect to the Marriott Cambridge Center

                                       -3-
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Hotel in Cambridge, Massachusetts for so long as it is a Borrowing Base
Property, for any rolling four (4) calendar quarters, determined as of the last
day of a calendar quarter, an amount equal to six percent (6%) of gross revenues
as determined in accordance with GAAP for such four (4) calendar quarters; (iii)
with respect to the Marriott Long Wharf Hotel in Boston, Massachusetts, for so
long as it is a Borrowing Base Property, for any rolling four (4) calendar
quarters, determined as of the last day of a calendar quarter, an amount equal
to five percent (5%) of gross revenues as determined in accordance with GAAP for
such four (4) calendar quarters; (iv) with respect to the Cambridge Residence
Inn in Cambridge, Massachusetts, for so long as it is a Borrowing Base Property,
for any rolling four (4) calendar quarters, determined as of the last day of a
calendar quarter, an amount equal to five percent (5%) of gross revenues as
determined in accordance with GAAP for such four (4) calendar quarters; and (v)
with respect to the hotel properties which are Borrowing Base Properties, other
than the Marriott Long Wharf Hotel, the Marriott Cambridge Center Hotel and the
Cambridge Residence Inn, for any rolling four (4) calendar quarters, determined
as of the last day of a calendar quarter, an amount equal to the applicable
percentage of gross revenues as determined in accordance with GAAP for such four
(4) calendar quarters, which is to be maintained on the books of the Borrower or
in a separate reserve account for the replacement or repair of such hotel's
furniture, fixtures and equipment pursuant to (and in no event less than as
required by) the applicable hotel management agreement or franchise agreement
(which such agreement shall be in form and substance customary for a national
hotel franchise).

    ANNUALIZED CAPITAL EXPENDITURES. (i) With respect to any Real Estate Assets
other than hotel properties, for any rolling four (4) calendar quarters,
determined as of the last day of a calendar quarter, an amount equal to $.25
MULTIPLIED BY the total number of square feet of the Real Estate Assets other
than hotel properties, on the last day of such calendar quarter; (ii) with
respect to the Marriott Cambridge Center Hotel in Cambridge, Massachusetts, for
any rolling four (4) calendar quarters, determined as of the last day of a
calendar quarter, an amount equal to six percent (6%) of gross revenues as
determined in accordance with GAAP for such four (4) calendar quarters; (iii)
with respect to the Marriott Long Wharf Hotel in Boston, Massachusetts, for any
rolling four (4) calendar quarters, determined as of the last day of a calendar
quarter, an amount equal to five percent (5%) of gross revenues as determined in
accordance with GAAP for such four (4) calendar quarters; (iv) with respect to
the Cambridge Residence Inn in Cambridge, Massachusetts, for any rolling four
(4) calendar quarters, determined as of the last day of a calendar quarter, an
amount equal to five percent (5%) of gross revenues as determined in accordance
with GAAP for such four (4) calendar quarters; and (v) with respect to the hotel
properties other than the Marriott Long Wharf Hotel, the Marriott Cambridge
Center Hotel and the Cambridge Residence Inn, for any rolling four (4) calendar
quarters, determined as of the last day of a calendar quarter, an amount equal
to the applicable percentage of gross revenues as determined in accordance with
GAAP for such four (4) calendar quarters, which percentage shall be the
percentage for each such hotel as is to be maintained on the books of the
Borrower or in a separate reserve account for the replacement or repair of such
hotel's furniture, fixtures and equipment pursuant to (and in

                                       -4-
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no event less than as required by) the applicable hotel management agreement or
franchise agreement (which such agreement shall be in form and substance
customary for a national hotel franchise).

    APPLICABLE L/C PERCENTAGE. With respect to any Letter of Credit, a per annum
percentage equal to the Applicable Eurodollar Margin in effect on the date on
which such Letter of Credit was issued.

    APPLICABLE EURODOLLAR MARGIN. With respect to Eurodollar Rate Loans, the
spread, expressed in basis points, over the Eurodollar Rate and used in
calculating the interest rate applicable to Eurodollar Rate Loans which spread
shall vary from time to time in relationship to variances in the Debt Ratings as
set forth below. The applicable Debt Ratings and Eurodollar Spreads (bps) for
Eurodollar Rate Loans are as set forth in the following table:

<Table>
<Caption>

          S&P                 Moody's             Eurodollar spread (bps)
          ---                 -------             -----------------------
          <S>                 <C>                 <C>
          A- or above         A3 or above         55.0

          BBB+                Baa1                65.0

          BBB                 Baa2                70.0

          BBB-                Baa3                90.0

          Below BBB- or       Below Baa3 or
          unrated             unrated            125.0
</Table>

In the event the Debt Ratings from the two agencies referred to above are not
equivalent, the Eurodollar Spread (bps) will be determined (i) based on the
higher of the two Debt Ratings if the lower Debt Rating is no more than one
level lower than the higher Debt Rating, and (ii) based on the average of the
two Debt Ratings if the lower Debt Rating is more than one level lower than the
higher Debt Rating. Adjustments in the Eurodollar Spread (bps) for a Eurodollar
Rate Loan based upon a change in a Debt Rating level shall be effective on the
first day following the change in such Debt Rating.

The Borrower shall notify the Agent in writing of any change in the Debt Rating
as and when such change occurs.

    APPLICABLE PRIME RATE MARGIN. Zero.

    APPROVED CONDOMINIUM PROPERTY. A Real Estate Asset which is a condominium
unit and in which a member of the BP Group owns 100% of the interests (including
100% of the unit owner's voting rights) in the unit, PROVIDED that the Agent has
reviewed and approved the condominium documents governing such condominium (and
such documents are not amended thereafter) with such approval not to be
unreasonably withheld (it being acknowledged that unless the Agent has raised an
objection with 14

                                       -5-
<Page>

days after it has received copies of the applicable condominium documents, the
Agent shall be deemed to have approved such documents). The Agent hereby
acknowledges that, as of the date hereof, 111 Huntington Avenue, 399 Park Avenue
and the Citigroup Center Property are Approved Condominium Properties.
Notwithstanding the foregoing, an Approved Condominium Property which is not
100% owned by the Borrower (including 100% of the unit owner's voting rights)
may not be or become a Borrowing Base Property without the prior written consent
of the Majority Banks.

    ARRANGER. Fleet Securities, Inc.

    ASSUMED TEST DEBT SERVICE. For any fiscal quarter, an amount equal to the
aggregate amount determined to be the payments which would be required during
such quarter to amortize the average amount of Unsecured Consolidated Total
Indebtedness outstanding during such quarter with respect to the Borrowing Base
Properties, using a twenty-five (25) year mortgage style amortization schedule,
and using an annual interest rate equal to the sum of two percent (2%) PLUS the
imputed seven (7) year United States Treasury notes annual yield as of the last
day of such fiscal quarter based upon published quotes for Treasury notes having
seven (7) years to maturity.

    ASSIGNMENT AND ASSUMPTION. See Section 20.1.

    BANKS. Collectively, Fleet and the other lending institutions listed on
SCHEDULE 2 hereto and any other banks which may provide additional commitments
and become parties to this Agreement, and any other Person who becomes an
assignee of any rights of a Bank pursuant to Section 20 or a Person who acquires
all or substantially all of the stock or assets of a Bank.

    BID RATE ADVANCE. A borrowing consisting of simultaneous Bid Rate Loans to
the Borrower from each of the Banks whose offer to make a Bid Rate Loan as part
of such borrowing has been accepted by the Borrower under the applicable auction
bidding procedure described in Section 2.9.

    BID RATE ADVANCE BORROWING NOTICE. See Section 2.9(b)(i).

    BID RATE LOAN. A loan by a Bank to the Borrower as part of a Bid Rate
Advance resulting from the applicable auction bidding procedure described in
Section 2.9.

    BID RATE MAXIMUM AMOUNT. At any particular time of reference, an amount
equal to fifty percent (50%) of the Total Commitment then in effect.

    BID RATE NOTES. The promissory notes substantially in the form of Exhibit
D-1 hereto which evidence the Bid Rate Loans.

    BORROWER. See the preamble hereto.

                                       -6-
<Page>

    BORROWING BASE. As determined from time to time, the Borrowing Base
Properties.

    BORROWING BASE AVAILABILITY. As at any date of determination an amount equal
to the Eligible Amount on such date MINUS the Maximum Drawing Amount on such
date.

    BORROWING BASE CONDITIONS. See definition of "Borrowing Base Property".

    BORROWING BASE DEBT SERVICE COVERAGE RATIO. As of any date of determination,
the ratio of (i) Borrowing Base Net Operating Income as determined on such date
DIVIDED BY 4, to (ii) the Assumed Test Debt Service applicable to the quarter
upon which the Borrowing Base Net Operating income was based.

    BORROWING BASE NET OPERATING INCOME. As of any date of determination, the
Net Operating Income calculated with respect to the Real Estate Assets which are
Borrowing Base Properties during the quarter upon which such Net Operating
Income is based, PROVIDED that such Net Operating Income shall be adjusted on a
PRO FORMA basis to account for Real Estate Assets that were acquired by the
Borrower and added to the Borrowing Base during such quarter by projecting the
results generated by any such Real Estate Asset for the portion of the
applicable quarter during which the Borrower owned (or ground-leased) such Real
Estate Asset over the entire applicable quarter.

    BORROWING BASE PROPERTY. As of any date of determination, an Unencumbered
Asset owned by the Borrower that: (i) is a Permitted Property, (ii) is not the
subject of a Disqualifying Structural Event, (iii) is not the subject of a
Disqualifying Environmental Event, (iv) is not a Real Estate Asset Under
Development, (v) is wholly-owned or ground-leased by the Borrower or is an
Approved Condominium Property which is a Permitted Property, (vi) is not subject
to a Non-Material Breach, and (vii) has been designated by the Borrower in
writing to the Agent as a Real Estate Asset that is a Borrowing Base Property,
PROVIDED that on such date of determination, the Unencumbered Assets that are
Borrowing Base Properties, taken as a whole, shall have been 85% leased in the
aggregate as of the date of such determination, and PROVIDED, FURTHER, that each
request to include an Unencumbered Asset as a Borrowing Base Property shall be
accompanied by a compliance certificate in the form of EXHIBIT C-5 attached
hereto (the foregoing clauses (i) through (vii) and the succeeding PROVISOS
being herein referred to collectively as the "Borrowing Base Conditions"). The
Borrowing Base Properties that constitute the Borrowing Base on the Closing Date
are set forth on SCHEDULE 3.

    BORROWING BASE VALUE. As of any date of determination, an amount equal to
(x) the amount of Unrestricted Cash and Cash Equivalents of the Borrower on such
date PLUS (y) (i) the Borrowing Base Net Operating Income from the Borrowing
Base Properties as determined on such date, MINUS (ii) the amount by which the
Annualized Borrowing Base

                                       -7-
<Page>

Capital Expenditures applicable to the quarter upon which such Borrowing Base
Net Operating Income was based exceeds the amount deducted for Capital
Expenditures in determining such Borrowing Base Net Operating Income, with the
number resulting from such subtraction being DIVIDED BY the Capitalization Rate;
PROVIDED that (1) such Borrowing Base Net Operating Income shall be adjusted on
a PRO FORMA basis to account for Real Estate Assets that were acquired by the
Borrower and added to the Borrowing Base during such quarter by projecting the
results generated by any such Real Estate Asset for the portion of the
applicable quarter during which the Borrower owned (or ground-leased) such Real
Estate Asset over the entire applicable quarter, (2) with respect to a Real
Estate Asset that was a Real Estate Asset Under Development and for which the
Borrower has received a certificate of occupancy or such Real Estate Asset may
otherwise be lawfully occupied for its intended use and, to the extent that such
Real Estate Asset otherwise qualifies as a Borrowing Base Property, the Borrower
may calculate the Borrowing Base Value of such Real Estate Asset either in the
manner set forth above or at the cost basis value (or, with respect to 399 Park
Avenue, other fixed value as provided in this Agreement) for a period of twelve
months after the issuance of the certificate of occupancy or such Real Estate
Asset may otherwise be lawfully occupied for its intended use, and (3) with
respect to a Real Estate Asset (not a Real Estate Asset Under Development)
acquired by the Borrower after the date hereof, to the extent that such Real
Estate Asset otherwise qualifies as a Borrowing Base Property, the Borrower may
calculate the Borrowing Base Value of such Real Estate Asset either in the
manner set forth above or at the cost basis value (or, with respect to 399 Park
Avenue, other fixed value as provided in this Agreement) for a period of twelve
months after the date of acquisition by the Borrower, and PROVIDED, FURTHER,
that at no time may the Borrowing Base Value attributable to hotel properties
constitute more than 33 1/3% of the total Borrowing Base Value. For purposes of
determining Borrowing Base Value, from the Closing Date through June 29, 2003,
399 Park Avenue shall be included in the Borrowing Base at the fixed value equal
to $1,000,000,000 rather than at the value that would be attributable to it in
accordance with the calculation required above by this definition of Borrowing
Base Value, PROVIDED that (i) 399 Park Avenue must at all times meet the
requirements of a Borrowing Base Property and (ii) for the quarterly reporting
period ending on June 30, 2003 and for all periods thereafter, the Borrowing
Base Value attributable to 399 Park Avenue shall be determined in accordance
with the calculation required by the first sentence of this definition of
Borrowing Base Value.

    BP GROUP. Collectively, (i) BPLP, (ii) BPI, (iii) the respective
Subsidiaries of BPLP and BPI and (iv) the Partially-Owned Entities.

    BPI. Boston Properties, Inc., a Delaware corporation and the sole general
partner of the Borrower.

    BUILDINGS. Individually and collectively, the buildings, structures and
improvements now or hereafter located on the Real Estate Assets.

                                       -8-
<Page>

    BUSINESS DAY. Any day on which banking institutions in Boston,
Massachusetts, are open for the transaction of banking business and, in the case
of Eurodollar Rate Loans, also a day which is a Eurodollar Business Day.

    CAPITAL EXPENDITURES. Any expenditure for any item that would be treated or
defined as a capital expenditure under GAAP or the Code.

    CAPITALIZATION RATE. The Capitalization Rate shall be (i) 9.0% for Real
Estate Assets other than the CBD Properties, and (ii) 8.5% for Real Estate
Assets which are CBD Properties.

    CAPITALIZED LEASES. Leases under which the Borrower or any of its
Subsidiaries or any Partially-Owned Entity is the lessee or obligor, the
discounted future rental obligations under which are required to be capitalized
on the balance sheet of the lessee or obligor in accordance with GAAP.

    CBD PROPERTIES. Each of the Real Estate Assets listed on SCHEDULE 4 and each
other Real Estate Asset which is designated by the Agent and the Borrower as a
CBD Property from time to time.

    CERCLA. See Section 7.18.

    CITIGROUP CENTER PROPERTY. The property located at 153 East 53rd Street, New
York, New York and commonly referred to as the "Citigroup Center". The Agent
hereby acknowledges that, as of the date hereof, the Citigroup Center Property
is a CBD Property.

    CLOSING DATE. January 17, 2003.

    CODE. The Internal Revenue Code of 1986, as amended and in effect from time
to time.

    COMPLETED LOAN REQUEST. A loan request accompanied by all information
required to be supplied under the applicable provisions of Section 2.4.

    COMMITMENT. With respect to each Bank, the amount set forth from time to
time on SCHEDULE 2 hereto as the amount of such Bank's Commitment to make
Revolving Credit Loans to, and to participate in the issuance, extension and
renewal of Letters of Credit for the account of, the Borrower as such SCHEDULE 2
may be amended from time to time in accordance with the terms of this Agreement.

    COMMITMENT PERCENTAGE. With respect to each Bank, the percentage set forth
on SCHEDULE 2 hereto as such Bank's percentage of the Total Commitment, as such

                                       -9-
<Page>

SCHEDULE 2 may be amended from time to time in accordance with the terms of this
Agreement.

    CONSOLIDATED OR CONSOLIDATED. With reference to any term defined herein,
shall mean that term as applied to the accounts of the Borrower and its
Subsidiaries, or BPI and its Subsidiaries (as the case may be), consolidated in
accordance with GAAP in accordance with the terms of this Agreement.

    CONSOLIDATED EBITDA. In relation to the Borrower and its Subsidiaries for
any fiscal quarter, an amount equal to, without double-counting, the net income
or loss of the Borrower and its Subsidiaries determined in accordance with GAAP
(before minority interests and excluding the adjustment for so-called
"straight-line rent accounting") for such quarter, PLUS (x) the following to the
extent deducted in computing such Consolidated net income for such quarter: (i)
Consolidated Total Interest Expense for such quarter, (ii) real estate
depreciation, amortization and extraordinary items for such quarter, and (iii)
other non-cash charges for such quarter; and MINUS (y) (i) all gains (or PLUS
all losses) attributable to the sale or other disposition of assets or debt
restructurings in such quarter, in each case (i.e., (x) and (y)(i) hereof)
adjusted to include the Borrower's or any Subsidiary's PRO RATA share of EBITDA
from any Partially-Owned Entity in such quarter, based on its percentage
ownership interest in such Partially-Owned Entity (or such other amount to which
the Borrower or such Subsidiary is entitled or for which the Borrower or such
Subsidiary is obligated based on an arm's length agreement), and (ii) for the
purposes of calculating Consolidated Total Adjusted Asset Value only, all
interest income of the Borrower and its Subsidiaries received in connection with
any Mortgages. In determining Consolidated EBITDA for the purposes of
calculating Fair Market Value of Real Estate Assets and Consolidated Total
Adjusted Asset Value only, any and all income of the Borrower and its
Subsidiaries received from any Real Estate Asset that is included in such
calculations at its cost basis value (or, as to 399 Park Avenue, other fixed
value as provided in this Agreement) shall be excluded.

    CONSOLIDATED FIXED CHARGES. For any fiscal quarter, an amount equal to (i)
Consolidated Total Interest Expense for such quarter PLUS (ii) the aggregate
amount of scheduled principal payments of Indebtedness (excluding optional
prepayments, balloon payments at maturity and any mid-term balloon payments of
principal with respect to Indebtedness otherwise requiring equal periodic
amortization payments of principal and interest over the term of such
Indebtedness (and any balloon payments at maturity with respect to such
Indebtedness)) required to be made during such quarter by the Borrower and its
Subsidiaries on a Consolidated basis PLUS (iii) the aggregate amount of
capitalized interest required in accordance with GAAP to be paid or accrued
during such quarter by the Borrower and its Subsidiaries PLUS (iv) Annualized
Capital Expenditures applicable to such quarter DIVIDED BY 4 PLUS (v) the
dividends and distributions, if any, paid or required to be paid during such
quarter on the Preferred Equity (Section 10.3(B)) or the Preferred Creditor
Equity (Section 10.3(A)), as applicable, of the Borrower, BPI or any of their
respective Subsidiaries.

                                      -10-
<Page>

    CONSOLIDATED NET WORTH. As of any date of determination, an amount equal to
the Consolidated net worth of the Borrower and its Subsidiaries, as determined
in accordance with GAAP.

    CONSOLIDATED TOTAL ADJUSTED ASSET VALUE. As of any date of determination, an
amount equal to the sum of (i) the Fair Market Value of Real Estate Assets as of
such date, PLUS (ii) 100% of the value of Unrestricted Cash and Cash Equivalents
on such date, PLUS (iii) 100% of the Development Costs incurred and paid to date
by the Borrower with respect to any Real Estate Assets which are Real Estate
Assets Under Development on such date, provided that, for purposes of this
clause (iii), the aggregate amount of Development Costs included in the
calculation of Consolidated Total Adjusted Asset Value shall not exceed an
amount equal to 20% of the sum of the Fair Market Value of Real Estate Assets on
such date PLUS the value of Unrestricted Cash and Cash Equivalents on such date
(the "Eligible Real Estate Development Costs"), PLUS (iv) with respect to each
Mortgage, the lesser of (y) the aggregate amount of principal under such
Mortgage that will be due and payable to the Borrower or its Subsidiaries (to
the extent of Borrower's direct or indirect interest therein) and (z) the
purchase price paid by the Borrower or one of its Subsidiaries to acquire such
Mortgage, PLUS (v) Accounts Receivable as of such date, PLUS (vi) 100% of the
value (determined on the so-called mark-to-market basis) of the Marketable
Securities owned by the Borrower or its Subsidiaries on such date, PROVIDED that
(1) the aggregate value attributed to such Marketable Securities which are not
of the type described in clauses (a), (b) or (c) of Section 9.3 may not exceed
2% of the Consolidated Total Adjusted Asset Value at any time, and (2) such
Marketable Securities must not be subject to any lock-up or other transfer
restrictions, plus (vii) the book value of land owned by the Borrower, as
evidenced by the Borrower's balance sheet delivered to the Agent.
Notwithstanding the foregoing, at any time at which the value determined
pursuant to clause (iv) of the preceding sentence equals or exceeds 10% of the
total Fair Market Value of Real Estate Assets at such time, then upon the
occurrence of an event of default under any Mortgage, the portion of the value
of such defaulted Mortgage which is in excess of 10% of the total Fair Market
Value of Real Estate Assets at such time ("Excess Value") shall be reduced to
seventy-five percent (75%) of the Excess Value as determined in this
subparagraph (iv) until the earlier to occur of (a) the event of default under
the Mortgage is cured in a commercially reasonable manner and (b) one hundred
eighty (180) days after the occurrence of the event of default; thereafter, if
the event of default under the defaulted Mortgage has not been cured in a
commercially reasonable manner, the portion of the value of the defaulted
Mortgage which is in excess of 10% of the total Fair Market Value of Real Estate
Assets at such time shall be reduced to fifty percent (50%) of the Excess Value
as determined as set forth above until the earlier to occur of (a) the event of
default under the Mortgage is cured in a commercially reasonable manner and (b)
eighteen (18) months after the occurrence of the event of default; thereafter,
if the event of default under the defaulted Mortgage has not been cured in a
commercially reasonable manner, the portion of the

                                      -11-
<Page>

value of the defaulted Mortgage which is in excess of 10% of the total Fair
Market Value of Real Estate Assets at such time shall be reduced to zero.

    CONSOLIDATED TOTAL INDEBTEDNESS. As of any date of determination,
Consolidated Total Indebtedness means for the Borrower and its Subsidiaries, the
sum of (without double-counting) but subject to the limitations set forth below,
(i) all Accounts Payable on such date, (ii) all Indebtedness outstanding on such
date, and (iii) all Letters of Credit outstanding on such date, in each case
whether Recourse, Without Recourse or contingent, PROVIDED, however, that
amounts not drawn under the Revolving Credit Loans or any other Indebtedness on
such date shall not be included in calculating Consolidated Total Indebtedness,
and PROVIDED, FURTHER, that (without double-counting), (x) each of the following
shall be included in Consolidated Total Indebtedness: (a) all amounts of
guarantees, indemnities for borrowed money, stop-loss agreements and the like
provided by the Borrower or any of its Subsidiaries, in each case in connection
with and guarantying repayment of amounts outstanding under any other
Indebtedness; (b) all amounts for which a letter of credit has been issued for
the account of the Borrower or any of its Subsidiaries; (c) all amounts of bonds
posted by the Borrower or any of its Subsidiaries guaranteeing performance or
payment obligations; and (d) all liabilities of the Borrower or any of its
Subsidiaries as partners, members or the like for liabilities (whether such
liabilities are Recourse, Without Recourse or contingent obligations of the
applicable partnership or other Person) of partnerships or other Persons in
which any of them have an equity interest, which liabilities are for borrowed
money or any of the matters listed in clauses (a), (b) or (c), and (y) each of
the following shall be excluded from Consolidated Total Indebtedness: (a)
defeased Indebtedness of the Borrower and its Subsidiaries; and (b) Indebtedness
of the Borrower and its Subsidiaries secured by Unrestricted Cash and Cash
Equivalents (it being agreed that, for this purpose, a lien on such Unrestricted
Cash or Cash Equivalents in favor of the Person holding such Indebtedness shall
not be deemed a "Lien" for purposes of the definition of Unrestricted Cash and
Cash Equivalents). Notwithstanding the foregoing (without double counting), with
respect to any Partially-Owned Entity, (x) to the extent that the Borrower or
any Subsidiary or such Partially-Owned Entity is providing a completion guaranty
in connection with a construction loan entered into by a Partially-Owned Entity,
Consolidated Total Indebtedness shall only include the Borrower's or such
Subsidiary's PRO RATA liability under the Indebtedness relating to such
completion guaranty (or, if greater, but without double-counting, the Borrower's
or such Subsidiary's liability under such completion guaranty (it being agreed
that to the extent that the liability of the Borrower or its Subsidiaries under
such completion guaranty would not constitute a liability (contingent or
otherwise) under GAAP, such liability will not be included in Consolidated Total
Indebtedness)) and (y) in connection with the liabilities described in clauses
(a) and (d) above, the Borrower shall be required to include in Consolidated
Total Indebtedness the portion of the liabilities of such Partially-Owned Entity
which are attributable to the Borrower's or such Subsidiary's percentage equity
interest in such Partially-Owned Entity or such other amount (if greater) of
such liabilities for which the Borrower or its Subsidiaries are, or have agreed
to be, liable by way of guaranty,

                                      -12-
<Page>

indemnity for borrowed money, stop-loss agreement or the like (excluding
liability under completion guaranties, which shall be included as and to the
extent set forth in clause (x) of this sentence)), it being agreed that
Indebtedness of a Partially-Owned Entity shall not be excluded from Consolidated
Total Indebtedness by virtue of the liability of such Partially-Owned Entity
being Without Recourse. For purposes hereof, the value of Accounts Payable shall
be determined in accordance with GAAP, and the amount of borrowed money shall
equal the sum of (1) the amount of borrowed money as determined in accordance
with GAAP PLUS (2) the amount of those contingent liabilities for borrowed money
set forth in subsections (a) through (d) above, but shall exclude any adjustment
for so-called "straight-line interest accounting" or the "constant yield to
maturity method" required under GAAP.

    CONSOLIDATED TOTAL INTEREST EXPENSE. For any fiscal quarter, the aggregate
amount of interest required in accordance with GAAP to be paid or accrued (but
excluding interest funded from the proceeds of any construction loan), without
double-counting, by the Borrower and its Subsidiaries during such quarter on:
(i) all Indebtedness of the Borrower and its Subsidiaries (including the Loans
and including original issue discount and amortization of prepaid interest, if
any), (ii) all amounts available for borrowing, or for drawing under letters of
credit, if any, issued for the account of the Borrower or any of its
Subsidiaries, but only if such interest was or is required to be reflected as an
item of expense, and (iii) all commitment fees, agency fees, facility fees,
balance deficiency fees and similar fees and expenses in connection with the
borrowing of money.

    CONVERSION REQUEST. A notice given by the Borrower to the Agent of its
election to convert or continue a Loan in accordance with Section 2.5.

    DEBT RATING. The credit rating assigned by either or both of S&P and/or
Moody's to (i) BPLP's senior, long-term unsecured debt, or (ii) BPLP's private
debt, PROVIDED that the Agent shall have the right to require a review and
confirmation of any such private debt rating, but shall not require such review
and confirmation more than twice a year unless a Default or Event of Default has
occurred and is continuing.

    DEFAULT. When used with reference to this Agreement or any other Loan
Document, an event or condition specified in Section 14.1 that, but for the
requirement that time elapse or notice be given, or both, would constitute an
Event of Default.

    DELINQUENT BANK. See Section 16.5 (c).

    DEVELOPMENT COSTS. Construction, development and/or acquisition costs
relating to a Real Estate Asset Under Development, PROVIDED that for Real Estate
Assets Under Development owned by any Partially-Owned Entity, the Development
Costs of such Real Estate Asset Under Development shall only be the Borrower's
pro-rata share of the Development Costs of such Real Estate Asset Under
Development (based on the greater

                                      -13-
<Page>

of (x) the Borrower's percentage equity interest in such Partially-Owned Entity
or (y) the Borrower's obligation to provide funds to such Partially-Owned
Entity).

    DISQUALIFYING ENVIRONMENTAL EVENT. Any Release or threatened Release of
Hazardous Substances, any violation of Environmental Laws or any other similar
environmental event with respect to any Borrowing Base Property that will, in
the Borrower's and the Agent's reasonable opinion cost in excess of (x) with
respect to CBD Properties, $10,000,000 and (y) with respect to all other
Borrowing Base Properties, $1,000,000 to remediate or, which, with respect to
the Borrowing Base Properties, will, in the Borrower's and Agent's reasonable
opinion cost in excess of $35,000,000 in the aggregate to remediate, PROVIDED
that (i) with respect to any particular Borrowing Base Property, if, in the
Agent's reasonable opinion, such environmental events will cost in excess of the
$1,000,000 or $10,000,000 cost basket, as applicable, but such environmental
events do not have a material adverse impact on the use and occupancy of such
Borrowing Base Property, (A) such Borrowing Base Property will be permitted to
remain in the Borrowing Base unless and until the Agent determines, in its
reasonable opinion, that such environmental events do have a material adverse
impact on such use and occupancy, and (B) the Borrowing Base Value attributable
to such Borrowing Base Property shall be reduced by an amount equal to the
aggregate of all costs in excess of the applicable cost basket, net of such
costs covered by an indemnification in favor of the Borrower, in form and
substance satisfactory to the Agent from a third party who, in the reasonable
opinion of the Agent, is a credit-worthy entity, and (ii) in the event the
Borrower and the Agent determine that environmental events will cost in excess
of $35,000,000 in the aggregate to remediate for all Borrowing Base Properties,
the Borrowing Base Value shall be reduced by an amount equal to the aggregate of
all costs in excess of such $35,000,000 to the extent such costs in excess of
$35,000,000 are not covered by an indemnification in favor of the Borrower, in
form and substance satisfactory to the Agent from a third party who, in the
reasonable opinion of the Agent, is a credit-worthy entity.

    DISQUALIFYING STRUCTURAL EVENT. Any structural issue, which, with respect to
any Borrowing Base Property other than rehab properties, will, in the Borrower's
and the Agent's reasonable opinion cost in excess of (x) with respect to CBD
Properties, $10,000,000 and (y) all other Borrowing Base Properties, $1,000,000
to fix or, which, with respect to the Borrowing Base Properties other than rehab
properties, will, in the Borrower's and Agent's reasonable opinion cost in
excess of $35,000,000 in the aggregate to fix, PROVIDED that (i) with respect to
any particular Borrowing Base Property, if, in the Agent's reasonable opinion,
such structural issues will cost in excess of the $1,000,000 or $10,000,000 cost
basket, as applicable, but such structural issues do not have a material adverse
impact on the use and occupancy of such Borrowing Base Property, (A) such
Borrowing Base Property will be permitted to remain in the Borrowing Base unless
and until the Agent determines, in its reasonable opinion, that such structural
issues do have a material adverse impact on such use and occupancy, and (B) the
Borrowing Base Value attributable to such Borrowing Base Property shall be
reduced by

                                      -14-
<Page>

an amount equal to the aggregate of all costs in excess of the applicable cost
basket, and (ii) in the event the Borrower and the Agent determine that such
structural issues will cost in excess of $35,000,000 in the aggregate to fix for
all Borrowing Base Properties, the Borrowing Base Value shall be reduced by an
amount equal to the aggregate of all costs in excess of such $35,000,000.

    DISTRIBUTION. With respect to:

               (i)   the Borrower, any distribution of cash or other cash
          equivalent, directly or indirectly, to the partners of the Borrower;
          or any other distribution on or in respect of any partnership
          interests of the Borrower; and

               (ii)  BPI, the declaration or payment of any dividend on or in
          respect of any shares of any class of capital stock of BPI, other than
          dividends payable solely in shares of common stock by BPI; the
          purchase, redemption, or other retirement of any shares of any class
          of capital stock of BPI, directly or indirectly through a Subsidiary
          of BPI or otherwise; the return of capital by BPI to its shareholders
          as such; or any other distribution on or in respect of any shares of
          any class of capital stock of BPI.

    DOLLARS OR $. Lawful currency of the United States of America.

    DRAWDOWN DATE. The date on which any Revolving Credit Loan is made or is to
be made, and the date on which any Revolving Credit Loan is converted or
continued in accordance with Section 2.5.

    ELIGIBLE AMOUNT. As of the date that any Loan is to be made hereunder, an
amount equal to the lesser of (i) the maximum amount that would permit Unsecured
Consolidated Total Indebtedness (exclusive of Accounts Payable, but including
amounts outstanding under any Loans and Letters of Credit after giving effect to
Loan Requests) to be less than 60% of the aggregate Borrowing Base Value on such
date (the "Advance Rate"), provided that at any time when Consolidated Total
Indebtedness equals or exceeds 60% of Consolidated Total Adjusted Asset Value,
as evidenced by the most recent financial statements delivered by the Borrower
pursuant to Section Section 8.4(a) and (b), the Advance Rate shall equal 55%,
and (ii) the maximum amount that would permit the Borrowing Base Debt Service
Coverage Ratio (after giving effect to such Loan) to be no less than 1.4 to 1.0.

    ELIGIBLE ASSIGNEE. Any of (a) a commercial bank (or similar financial
institution) organized under the laws of the United States, or any State thereof
or the District of Columbia, and having total assets in excess of
$1,000,000,000; (b) a savings and loan association or savings bank organized
under the laws of the United States, or any State

                                      -15-
<Page>

thereof or the District of Columbia, and having a net worth of at least
$100,000,000, calculated in accordance with GAAP; and (c) a commercial bank (or
similar financial institution) organized under the laws of any other country
(including the central bank of such country) which is a member of the
Organization for Economic Cooperation and Development (the "OECD"), or a
political subdivision of any such country, and having total assets in excess of
$1,000,000,000, PROVIDED that such bank (or similar financial institution) is
acting through a branch or agency located in the United States of America.

    ELIGIBLE REAL ESTATE DEVELOPMENT COSTS. See definition of "Consolidated
Total Adjusted Asset Value".

    EMBARCADERO CENTER PROPERTY. Collectively, the properties located in the
financial district of San Francisco, California, and consisting of One
Embarcadero Center, Two Embarcadero Center, Three Embarcadero Center, Four
Embarcadero Center, Embarcadero Center West and the Federal Reserve Building.

    EMPLOYEE BENEFIT PLAN. Any employee benefit plan within the meaning of
Section 3(3) of ERISA maintained or contributed to by the Borrower or any ERISA
Affiliate, other than a Multiemployer Plan.

    ENVIRONMENTAL LAWS. See Section 7.18(a).

    ENVIRONMENTAL REPORTS. See Section 7.18

    ERISA. The Employee Retirement Income Security Act of 1974, as amended and
in effect from time to time.

    ERISA AFFILIATE. Any Person which is treated as a single employer with the
Borrower under Section 414 of the Code.

    ERISA REPORTABLE EVENT. A reportable event with respect to a Guaranteed
Pension Plan within the meaning of Section 4043 of ERISA and the regulations
promulgated thereunder as to which the requirement of notice has not been
waived.

    EUROCURRENCY RESERVE RATE. For any day with respect to a Eurodollar Rate
Loan, the maximum rate (expressed as a decimal) at which any Bank subject
thereto would be required to maintain reserves under Regulation D of the Board
of Governors of the Federal Reserve System (or any successor or similar
regulations relating to such reserve requirements) against "Eurocurrency
Liabilities" (as that term is used in said Regulation D), if such liabilities
were outstanding. The Eurocurrency Reserve Rate shall be adjusted automatically
on and as of the effective date of any change in the Eurocurrency Reserve Rate.

                                      -16-
<Page>

    EURODOLLAR BREAKAGE COSTS. With respect to any Eurodollar Rate Loan to be
prepaid prior to the end of the applicable Interest Period or not borrowed,
converted or continued ("drawn" and, with correlative meaning, "draw") after
elected, a prepayment "breakage" fee in an amount determined by the Agent in the
following manner:

               (i)   First, the Agent shall determine the amount by which (a)
          the total amount of interest which would have otherwise accrued
          hereunder on each installment of principal prepaid or not so drawn,
          during the period beginning on the date of such prepayment or failure
          to draw and ending on the last day of the applicable Eurodollar Rate
          Loan Interest Period (the "Reemployment Period"), exceeds (b) the
          total amount of interest which would accrue, during the Reemployment
          Period, on any readily marketable bond or other obligation of the
          United States of America designated by the Agent in its sole
          discretion at or about the time of such payment, such bond or other
          obligation of the United States of America to be in an amount equal
          (as nearly as may be) to the amount of principal so paid or not drawn
          after elected and to have maturity at the end of the Reemployment
          Period, and the interest to accrue thereon to take account of
          amortization of any discount from par or accretion of premium above
          par at which the same is selling at the time of designation. Each such
          amount is hereinafter referred to as an "Installment Amount".

               (ii)  Second, each Installment Amount shall be treated as payable
          on the last day of the Eurodollar Rate Loan Interest Period which
          would have been applicable had such principal installment not been
          prepaid or not drawn.

               (iii) Third, the amount to be paid on each such date shall be the
          present value of the Installment Amount determined by discounting the
          amount thereof from the date on which such Installment Amount is to be
          treated as payable, at the same yield to maturity as that payable upon
          the bond or other obligation of the United States of America
          designated as aforesaid by the Agent.

    EURODOLLAR BUSINESS DAY. Any day on which commercial banks are open for
international business (including dealings in Dollar deposits) in London or such
other eurodollar interbank market as may be selected by the Agent in its sole
discretion acting in good faith.

    EURODOLLAR RATE. For any Interest Period with respect to a Eurodollar Rate
Loan, the rate per annum equal to the quotient (rounded upwards to the nearest
1/16 of one percent) of (a) the rate at which the Bank serving as the Agent is
offered Dollar deposits two Eurodollar Business Days prior to the beginning of
such Interest Period in an

                                      -17-
<Page>

interbank eurodollar market where the eurodollar and foreign currency and
exchange operations of the Bank serving as the Agent are customarily conducted
for delivery on the first day of such Interest Period for the number of days
comprised therein and in an amount comparable to the amount of the Eurodollar
Rate Loan to which such Interest Period applies, divided by (b) a number equal
to 1.00 MINUS the Eurocurrency Reserve Rate.

    EURODOLLAR RATE LOAN(S). Loans bearing interest calculated by reference to
the Eurodollar Rate.

    EVENT OF DEFAULT. See Section 14.1.

    EXCESS VALUE. See definition of "Consolidated Total Adjusted Asset Value".

    EXTENSION. See Section 2.11.

    FACILITY FEE. See Section 2.3(d).

                                      -18-
<Page>

    FAIR MARKET VALUE OF REAL ESTATE ASSETS. As of any date of determination,
the sum of (A) with respect to Real Estate Assets other than hotel properties,
an amount equal to (i)(x) Consolidated EBITDA for the most recent one (1)
complete fiscal quarter, MINUS (y) $.0625 MULTIPLIED BY the aggregate square
footage of all Real Estate Assets other than hotel properties at such date;
MULTIPLIED BY (ii) 4; with the product being DIVIDED BY (iii) the applicable
Capitalization Rate, PLUS (B) with respect to Real Estate Assets which are hotel
properties, an amount equal to (i)(x) Consolidated EBITDA for the most recent
four (4) consecutive complete fiscal quarters, MINUS (y) the respective
Annualized Capital Expenditure for each of the hotel properties; DIVIDED BY (ii)
the applicable Capitalization Rate. Notwithstanding the foregoing, (a) (i)
solely for the period commencing on the Closing Date and ending on June 29,
2003, the Fair Market Value of Real Estate Assets attributable to 399 Park
Avenue shall be an amount equal to $1,000,000,000 and (ii) for the quarterly
reporting period ending on June 30, 2003 and for all periods thereafter, the
Fair Market Value of Real Estate Assets attributable to 399 Park Avenue shall be
determined in accordance with the calculation required by the first sentence of
this definition, (b) with respect to a Real Estate Asset that was a Real Estate
Asset Under Development and for which the Borrower has received a certificate of
occupancy or such Real Estate Asset may otherwise be lawfully occupied for its
intended use, the Borrower may calculate the Fair Market Value of Real Estate
Assets of such Real Estate Asset either in the manner set forth in this
definition above or at the cost basis value (or, with respect to 399 Park
Avenue, other fixed value as provided in this Agreement) for a period of twelve
months after the issuance of the certificate of occupancy or such Real Estate
Asset may otherwise be lawfully occupied for its intended use, and (c) with
respect to a Real Estate Asset (not a Real Estate Asset Under Development)
acquired by the Borrower after the date hereof, the Borrower may calculate the
Fair Market Value of Real Estate Assets of such Real Estate Asset either in the
manner set forth in this definition above or at the cost basis value (or, with
respect to 399 Park Avenue, other fixed value as provided in this Agreement) for
a period of twelve months after the date of acquisition by the Borrower.

    FEDERAL FUNDS RATE. See definition of "Prime Rate".

    FINANCIAL STATEMENT DATE. September 30, 2002.

    FRONTING BANK. Fleet or such other Bank as the Borrower may identify in
accordance with Section 3.1.5.

    "FUNDS FROM OPERATIONS". As defined in accordance with resolutions adopted
by the Board of Governors of the National Association of Real Estate Investment
Trusts as in effect on the Closing Date.

    GAAP. Generally accepted accounting principles, consistently applied.

                                      -19-
<Page>

    GUARANTEED PENSION PLAN. Any employee pension benefit plan within the
meaning of Section 3(2) of ERISA maintained or contributed to by the Borrower or
BPI, as the case may be, or any ERISA Affiliate of any of them the benefits of
which are guaranteed on termination in full or in part by the PBGC pursuant to
Title IV of ERISA, other than a Multiemployer Plan.

    HAZARDOUS SUBSTANCES. See Section 7.18(b).

    INCREASE. See Section 2.10.

    INCREASE CONDITIONS. The satisfaction of each of the following:

          (a)  no Default or Event of Default shall have occurred and be
               continuing (both before and after giving effect to the Increase)
               and all representations and warranties contained in the Loan
               Documents shall be true and correct as of the effective date of
               the Increase (except (i) to the extent of changes resulting from
               transactions contemplated or not prohibited by this Agreement or
               the other Loan Documents (including, without limitation, the fact
               that a Real Estate Asset may cease to be a Borrowing Base
               Property pursuant to the terms of this Agreement) and changes
               occurring in the ordinary course of business, (ii) to the extent
               that such representations and warranties relate expressly to an
               earlier date and (iii) to the extent otherwise represented by the
               Borrower with respect to the representation set forth in Section
               7.10);

          (b)  the Increase shall be extended on the same terms and conditions
               applicable to the other Loans; and

          (c)  to the extent any portion of the Increase is committed to by a
               third party financial institution or institutions not already a
               Bank hereunder, such financial institution shall be approved by
               the Agent (such approval not to be unreasonably withheld or
               delayed) and each such financial institution shall have signed a
               counterpart signature page becoming a party to this Agreement and
               a "Bank" hereunder.

    INDEBTEDNESS. All of the following obligations without duplication: (a) the
Obligations to the extent outstanding from time to time; (b) all debt and
similar monetary obligations for borrowed money, whether direct or indirect; (c)
all other liabilities for borrowed money secured by any Lien existing on
property owned or acquired subject thereto, whether or not the liability secured
thereby shall have been assumed; (d) reimbursement obligations for letters of
credit; and (e) all guarantees, endorsements and other contingent obligations
for or in connection with borrowed money whether direct or indirect in respect
of indebtedness or obligations of others.

                                      -20-
<Page>

    INDEXED RATE AUCTION. With respect to a request by the Borrower for a Bid
Rate Advance, a solicitation in which the Borrower specifies in the Bid Rate
Advance Borrowing Notice that the rates of interest to be offered by the Banks
shall be rates per annum greater or less than the Eurodollar Rate plus the
Applicable Eurodollar Margin.

    INITIAL FINANCIAL STATEMENTS. See Section 7.4.

    INTEREST PAYMENT DATE. As to any Prime Rate Loan, the last day of any
calendar month in which such Loan is outstanding. As to any Eurodollar Rate
Loan, the last day of the applicable Interest Period and when such Loan is due,
and if such Interest Period is longer than three months, at intervals of three
months after the first day thereof. As to any Swingline Loan, the day such
Swingline Loan is due.

    INTEREST PERIOD. With respect to each Revolving Credit Loan, but without
duplication of any other Interest Period, (a) initially, the period commencing
on the Drawdown Date of such Loan and ending on the last day of one of the
following periods (as selected by the Borrower in a Completed Loan Request): (i)
for any Prime Rate Loan, the calendar month in which such Prime Rate Loan is
made (whether by borrowing or by conversion from a Eurodollar Rate Loan), and
(ii) for any Eurodollar Rate Loan, 1, 2, 3, 4 or 6 months; and (b) thereafter,
each period commencing at the end of the last day of the immediately preceding
Interest Period applicable to such Revolving Credit Loan and ending on the last
day of the applicable period set forth in (a)(i) and (ii) above (as selected by
the Borrower in a Conversion Request); PROVIDED that all of the foregoing
provisions relating to Interest Periods are subject to the following:

               (A) if any Interest Period with respect to a Prime Rate Loan
          would end on a day that is not a Business Day, that Interest Period
          shall end on the next succeeding Business Day;

               (B) if any Interest Period with respect to a Eurodollar Rate Loan
          would otherwise end on a day that is not a Business Day, that Interest
          Period shall be extended to the next succeeding Business Day unless
          the result of such extension would be to carry such Interest Period
          into another calendar month, in which event such Interest Period shall
          end on the immediately preceding Business Day;

               (C) if the Borrower shall fail to give notice of conversion as
          provided in Section 2.5, the Borrower shall be deemed to have
          requested a conversion of the affected Eurodollar Rate Loan to a Prime
          Rate Loan on the last day of the then current Interest Period with
          respect thereto;

               (D) any Interest Period relating to any Eurodollar Rate Loan that
          begins on the last Business Day of a calendar month (or on a day for

                                      -21-
<Page>

          which there is no numerically corresponding day in the calendar month
          at the end of such Interest Period) shall, subject to subparagraph (E)
          below, end on the last Business Day of a calendar month; and

               (E) any Interest Period that would otherwise extend beyond the
          Maturity Date shall end on the Maturity Date.

    INVESTMENTS. All expenditures made and all liabilities incurred
(contingently or otherwise, but without double-counting): (i) for the
acquisition of stock, partnership or other equity interests or for the
acquisition of Indebtedness of, or for loans, advances, capital contributions or
transfers of property to, any Person; (ii) in connection with Real Estate Assets
Under Development; and (iii) for the acquisition of any other obligations of any
Person. In determining the aggregate amount of Investments outstanding at any
particular time: (a) there shall be included as an Investment all interest
accrued with respect to Indebtedness constituting an Investment unless and until
such interest is paid; (b) there shall be deducted in respect of each such
Investment any amount received as a return of capital (but only by repurchase,
redemption, retirement, repayment, liquidating dividend or liquidating
distribution); (c) there shall not be deducted in respect of any Investment any
amounts received as earnings on such Investment, whether as dividends, interest
or otherwise, except that accrued interest included as provided in the foregoing
clause (a) may be deducted when paid; and (d) there shall not be deducted from
the aggregate amount of Investments any decrease in the value thereof.

    JOINDER DOCUMENTS. The one or more Joinder Agreements among the Agent, the
Banks and any Wholly-owned Subsidiary which is to become a Borrower at any time
after the Closing Date, the form of which is attached hereto as EXHIBIT G,
together with all other documents, instruments and certificates required by any
such Joinder Agreement to be delivered by such Wholly-owned Subsidiary to the
Agent and the Banks on the date such Wholly-owned Subsidiary becomes a Borrower
hereunder.

    LEASES. Leases, licenses and agreements, whether written or oral, relating
to the use or occupation of space in or on the Buildings or on the Real Estate
Assets by Persons other than the Borrower, its Subsidiaries or any
Partially-Owned Entity.

    LETTER OF CREDIT. See Section 3.1.1.

    LETTER OF CREDIT APPLICATION. See Section 3.1.1.

    LETTER OF CREDIT FEE. See Section 3.6.

    LETTER OF CREDIT PARTICIPATION. See Section 3.1.4.

    LIABILITIES. All obligations, contingent and otherwise, that in accordance
with GAAP should be classified upon the obligor's balance sheet as liabilities,
or to which

                                      -22-
<Page>

reference should be made by footnotes thereto, including in any event and
whether or not so classified: (a) all debt and similar monetary obligations,
whether direct or indirect, including, without limitation, all Indebtedness; (b)
all liabilities secured by any mortgage, pledge, security interest, lien,
charge, or other encumbrance existing on property owned or acquired subject
thereto, whether or not the liability secured thereby shall have been assumed;
and (c) all guarantees for borrowed money, endorsements and other contingent
obligations, whether direct or indirect, in respect of indebtedness or
obligations of others, including any obligation to supply funds (including
partnership obligations and capital requirements) to or in any manner to invest
in, directly or indirectly, the debtor, to purchase indebtedness, or to assure
the owner of indebtedness against loss, through an agreement to purchase goods,
supplies, or services for the purpose of enabling the debtor to make payment of
the indebtedness held by such owner or otherwise, and the obligations to
reimburse the issuer in respect of any letters of credit.

    LIEN. See Section 9.2.

    LOAN DOCUMENTS. Collectively, this Agreement, the Letter of Credit
Applications, the Letters of Credit, the Notes, the Joinder Documents and any
and all other agreements, instruments, documents or certificates now or
hereafter evidencing or otherwise relating to the Loans and executed and
delivered by or on behalf of the Borrower or its Subsidiaries or BPI or its
Subsidiaries in connection with or in any way relating to the Loans or the
transactions contemplated by this Agreement, and all schedules, exhibits and
annexes hereto or thereto, as any of the same may from time to time be amended
and in effect.

    LOANS. The Revolving Credit Loans, the Swingline Loans and the Bid Rate
Loans.

    MAJORITY BANKS. As of any date, the Banks whose aggregate Commitments
constitute at least fifty-one percent (51%) of the Total Commitment (or, if the
Commitments have been terminated, the Banks whose aggregate Commitments,
immediately prior to such termination, constituted at least fifty-one percent
(51%) of the Total Commitment).

    MARKETABLE SECURITIES. As of any date, the securities owned by the Borrower
or any of its Subsidiaries which are publicly traded on a nationally-recognized
exchange or in the over-the-counter markets.

    MATURITY DATE. January 17, 2006, or such earlier date (or later date
pursuant to Section 2.11) on which the Revolving Credit Loans shall become due
and payable pursuant to the terms hereof. The Maturity Date may be extended to
January 17, 2007 in accordance with the terms of Section 2.11.

                                      -23-
<Page>

    MAXIMUM DRAWING AMOUNT. The maximum aggregate amount that the beneficiaries
may at any time draw under outstanding Letters of Credit, as such maximum
aggregate amount may be reduced from time to time pursuant to the terms of the
Letters of Credit.

    MINIMUM COMMITMENT. With reference to the Bank serving as the Agent, a
Commitment equal to the greater of (i) $50,000,000 or (ii) an amount which is
greater than or equal to the Commitment of any other Bank.

    MOODY'S. Moody's Investors Service, Inc., and its successors.

    MORTGAGES. Mortgage debt instruments, in which the Borrower holds a direct
or indirect interest, for real estate that is developed.

    MULTIEMPLOYER PLAN. Any multiemployer plan within the meaning of Section
3(37) of ERISA maintained or contributed to by the Borrower or any Guarantor as
the case may be or any ERISA Affiliate.

    NET OPERATING INCOME. As at any date of determination, an amount equal to
(i) the aggregate rental and other income from the operation of all Real Estate
Assets during the most recent complete fiscal quarter, MULTIPLIED BY 4; MINUS
(ii) all expenses and other proper charges incurred in connection with the
operation of such Real Estate Assets (including, without limitation, real estate
taxes, management fees, bad debt expenses and rent under ground leases) during
the most recently completed fiscal quarter MULTIPLIED BY 4; but, in any case,
before payment of or provision for debt service charges for such fiscal quarter,
income taxes for such fiscal quarter, capital expenses for such fiscal quarter,
and depreciation, amortization, and other non-cash expenses for such fiscal
quarter, all as determined in accordance with GAAP (except that any rent
leveling adjustments shall be excluded from rental income).

    NON-MATERIAL BREACH. See Section 14.

    NOTE RECORD. A Record with respect to any Note.

    NOTES. The Revolving Credit Notes, the Swingline Note and the Bid Rate
Notes.

    OBLIGATIONS. All indebtedness, obligations and liabilities of the Borrower
and its Subsidiaries to any of the Banks and the Agent, individually or
collectively (but without double-counting), under this Agreement and each of the
other Loan Documents and in respect of any of the Loans and the Notes and
Reimbursement Obligations incurred and the Letter of Credit Applications and the
Letters of Credit and other instruments at any time evidencing any thereof,
whether existing on the date of this Agreement or arising or incurred hereafter,
direct or indirect, joint or several, absolute or contingent, matured or

                                      -24-
<Page>

unmatured, liquidated or unliquidated, secured or unsecured, arising by
contract, operation of law or otherwise.

    ORGANIZATIONAL DOCUMENTS. Collectively, (i) the Agreement of Limited
Partnership of BPLP, (ii) the Certificate of Limited Partnership of BPLP, (iii)
the Certificate of Incorporation of BPI, (iv) the by-laws of BPI, and (v) all of
the partnership agreements, corporate charters and by-laws, limited liability
company operating agreements, joint venture agreements or similar agreements,
charter documents and certificates or other agreements relating to the
formation, organization or governance of any Borrower (including, without
limitation, any Wholly-owned Subsidiary who becomes a Borrower from time to time
hereunder), in each case as any of the foregoing may be amended in accordance
with Section 8.21.

    PARTIALLY-OWNED ENTITY(IES). Any of the partnerships, associations,
corporations, limited liability companies, trusts, joint ventures or other
business entities in which the Borrower, directly, or indirectly through its
full or partial ownership of another entity, own an equity interest, but which
is not required in accordance with GAAP to be consolidated with the Borrower for
financial reporting purposes.

    PBGC. The Pension Benefit Guaranty Corporation created by Section 4002 of
ERISA and any successor entity or entities having similar responsibilities.

    PERMITS. All governmental permits, licenses, and approvals necessary for the
lawful operation and maintenance of the Real Estate Assets.

    PERMITTED LIENS. Liens permitted by Section 9.2.

    PERMITTED PROPERTY. A property which is an office property, an industrial
property or a hotel property (including any of such properties being
rehabilitated or expanded), including properties having uses ancillary to any of
the foregoing, including, without limitation, multifamily, retail and parking
facilities which are ancillary to any such office, industrial or hotel property,
and including, in any event, the Prudential Center in Boston, Massachusetts and
the Embarcadero Center Property.

    PERSON. Any individual, corporation, partnership, trust, limited liability
company, unincorporated association, business, or other legal entity, and any
government (or any governmental agency or political subdivision thereof).

    PREFERRED CREDITOR EQUITY. Any Preferred Equity issued by the Borrower, BPI
or any of their respective Subsidiaries which has any of the following
characteristics: (i) pursuant to the documents or agreements under which such
Preferred Equity was issued or is governed, the equity terms include any
covenant that the issuer must meet which, if breached, results in a default
permitting acceleration or other acceleration rights; or (ii) pursuant to the
documents or agreements under which such Preferred Equity was issued

                                      -25-
<Page>

or is governed, there are any required dividends or other mandatory payments on
the equity that, if not paid, create acceleration rights in favor of the holder.
The Agent acknowledges that (i) none of the Preferred Equity which exists as of
the date of this Agreement constitutes Preferred Creditor Equity and (ii) no
subsequently issued Preferred Equity which is issued on substantially the same
terms (including that it contains no terms of the nature described in clauses
(i) and (ii) above), and which is substantially similar in form and substance,
to the Preferred Equity which exists as of the date of this Agreement shall
constitute Preferred Creditor Equity.

    PREFERRED EQUITY. Any preferred stock, preferred partnership interests,
preferred member interests or other preferred equity interests issued by the
Borrower, BPI or any of their respective Subsidiaries (including, in any event,
the Preferred Creditor Equity).

    PRIME RATE. The higher of (i) the annual rate of interest announced from
time to time by Fleet at its head office in Boston, Massachusetts as its "Prime
Rate" and (ii) one half of one percent (1/2%) PLUS the overnight federal funds
effective rate as published by the Board of Governors of the Federal Reserve
System, as in effect from time to time (the "Federal Funds Rate"). Any change in
the Prime Rate during an Interest Period shall result in a corresponding change
on the same day in the rate of interest accruing from and after such day on the
unpaid balance of principal of the Prime Rate Loans, if any, applicable to such
Interest Period, effective on the day of such change in the Prime Rate.

    PRIME RATE LOANS. Those Loans bearing interest calculated by reference to
the Prime Rate.

    PROSPECTUS. Collectively, the prospectus relating to the common stock of BPI
and included in the Registration Statement, and each preliminary prospectus
relating thereto.

    PROTECTED INTEREST RATE AGREEMENT. An agreement which evidences the interest
protection arrangements required by Section 8.16, and all extensions, renewals,
modifications, amendments, substitutions and replacements thereof

    RCRA. See Section 7.18.

    REAL ESTATE ASSETS. The fixed and tangible properties consisting of land,
buildings and/or other improvements owned or ground-leased by the Borrower or by
any other member of the BP Group (other than BPI, except for the property
located at 100 East Pratt Street, Baltimore, Maryland) at the relevant time of
reference thereto, including, without limitation, the Borrowing Base Properties
at such time of reference, but excluding all leaseholds other than (i)
University Place, Cambridge, Massachusetts and (ii) other leaseholds which are
subject to ground leases having an unexpired term of not less than (a) thirty
(30) years from the date hereof or (b) twenty-seven (27) years from the date
hereof if in connection with a so-called reverse like-kind exchange (in either
such event, which ground lease unexpired term will include only renewal options
exercisable

                                      -26-
<Page>

solely at the ground lessee's option and, if exercisable prior to the Maturity
Date, so exercised). Notwithstanding the foregoing, (i) Real Estate Assets shall
also include each Approved Condominium Property, (ii) University Place SHALL NOT
be includable as a Borrowing Base Property if and so long as it remains subject
to a ground lease having an unexpired term of less than thirty (30) years from
the date hereof and (iii) 399 Park Avenue SHALL be includable as a Borrowing
Base Property if and so long as it remains subject to a ground lease having an
unexpired term of not less than twenty seven (27) years from the date hereof.

    REAL ESTATE ASSETS UNDER DEVELOPMENT. Any Real Estate Assets for which the
Borrower, any of the Borrower's Subsidiaries or any Partially-Owned Entity is
actively pursuing construction of one or more Buildings or other improvements
and for which construction is proceeding to completion without undue delay from
Permit denial, construction delays or otherwise, all pursuant to such Person's
ordinary course of business, PROVIDED that any such Real Estate Asset (or, if
applicable, any Building comprising a portion of any such Real Estate Asset)
will no longer be considered a Real Estate Asset Under Development when a
certificate of occupancy has issued for such Real Estate Asset (or Building) or
such Real Estate Asset (or Building) may otherwise be lawfully occupied for its
intended use. Notwithstanding the foregoing, tenant improvements (where
available) to previously constructed and/or leased Real Estate Assets shall not
be considered Real Estate Assets Under Development.

    RECORD. The grid attached to any Note, or the continuation of such grid, or
any other similar record, including computer records, maintained by any Bank
with respect to any Loan.

    RECOURSE. With reference to any obligation or liability, any liability or
obligation that is not Without Recourse to the obligor thereunder, directly or
indirectly. For purposes hereof, a Person shall not be deemed to be "indirectly"
liable for the liabilities or obligations of an obligor solely by reason of the
fact that such Person has an ownership interest in such obligor, PROVIDED that
such Person is not otherwise legally liable, directly or indirectly, for such
obligor's liabilities or obligations (e.g., by reason of a guaranty or
contribution obligation, by operation of law or by reason of such Person being a
general partner of such obligor).

    REFINANCING MORTGAGE. See Section 8.12.

    REGISTRATION STATEMENT. The registration statement on Form S-11 (File No.
333-25279) with respect to the common stock of BPI, which became effective in
June, 1997.

    REIMBURSEMENT OBLIGATION. The Borrower's obligation to reimburse the Banks
and the Agent on account of any drawing under any Letter of Credit as provided
in Section 3.2. Notwithstanding the foregoing, unless the Borrower shall notify
the Agent of its intent to repay the Reimbursement Obligation on the date of the
related drawing under any Letter

                                      -27-
<Page>

of Credit as provided in Section 3.2 and such Reimbursement Obligation is in
fact paid by the Borrower on such date, such Reimbursement Obligation shall
simultaneously with such drawing be converted to and become a Prime Rate Loan as
set forth in Section 3.3.

    REIT. A "real estate investment trust", as such term is defined in Section
856 of the Code.

    RELEASE. See Section 7.18(c)(iii).

    REQUIRED BANKS. As of any date, the Banks whose aggregate Commitments
constitute at least sixty-six and two-thirds percent (66-2/3%) of the Total
Commitment (or, if the Commitments have been terminated, the Banks whose
aggregate Commitments, immediately prior to such termination, constituted at
least sixty-six and two-thirds percent (66-2/3%) of the Total Commitment).

    REVOLVING CREDIT LOAN(S). Each and every revolving credit loan made or to be
made or deemed made by the Banks to the Borrower pursuant to Section 2 or
Section 3.3, and excluding, in any event all Swingline Loans and all Bid Rate
Loans.

    REVOLVING CREDIT NOTES. Collectively, the separate promissory notes of the
Borrower in favor of each Bank in substantially the form of EXHIBIT A hereto, in
an aggregate principal amount equal to $605,000,000 or such greater amount to
which the Total Commitment is increased pursuant to Section 2.10, dated as of
the date hereof or as of such later date as any Person becomes a Bank under this
Agreement, and completed with appropriate insertions, as each of such notes may
be amended and/or restated from time to time.

    S&P. Standard & Poor's Ratings Group, a division of McGraw-Hill, Inc., and
its successors.

    SARA. See Section 7.18.

    SEC. The Securities and Exchange Commission, or any successor thereto.

    SEC FILINGS. Collectively, (i) the Registration Statement, (ii) the
Prospectus, (iii) each so-called follow-on prospectus filed by BPI with the SEC
from time to time, (v) each Form 10-K and Form 8-K filed by BPI with the SEC
from time to time and (vi) each of the other public forms and reports filed by
BPI with the SEC from time to time.

    SECURED CONSOLIDATED TOTAL INDEBTEDNESS. As of any date of determination,
the aggregate principal amount of Consolidated Total Indebtedness of the
Borrower and its Subsidiaries outstanding at such date secured by a Lien
evidenced by a mortgage, deed of trust or other similar security instrument on
properties or other assets of the Borrower or its Subsidiaries, without regard
to Recourse.

                                      -28-
<Page>

    SUBSIDIARY. Any corporation, association, partnership, limited liability
company, trust, joint venture or other business entity which is required to be
consolidated with the Borrower or BPI in accordance with GAAP.

    SWINGLINE COMMITMENT. The obligation of the Swingline Lender to make
Swingline Loans to the Borrower in a maximum principal amount not exceeding at
any time $60,000,000.

    SWINGLINE LENDER. Fleet, in its capacity as swingline lender hereunder, or
any Eligible Assignee of Fleet who executes an Assignment and Assumption
assuming Fleet's obligations as Swingline Lender.

    SWINGLINE LOANS. Collectively, the loans in the maximum aggregate principal
amount of the Swingline Commitment made or to be made by the Swingline Lender to
the Borrower pursuant to Section 2.8 and subject to the limitations contained
herein and with each such Swingline Loan bearing interest at a per annum rate
equal to the Prime Rate.

    SWINGLINE LOAN AMOUNT. See Section 2.8(b).

    SWINGLINE NOTE. The promissory note substantially in the form of Exhibit A-1
hereto which evidences the Swingline Loans.

    SWINGLINE TERMINATION DATE. The date which is no later than the 15th day
preceding the Maturity Date.

    TOTAL COMMITMENT. As of any date, the sum of the then current Commitments of
the Banks. As of the Closing Date, the Total Commitment (including the Swingline
Commitment) is $605,000,000. After the Closing Date, the aggregate amount of the
Total Commitment (including the Swingline Commitment) may be increased to an
amount not exceeding $805,000,000, PROVIDED that such Increase is in accordance
with the provisions of Section 2.10.

    TYPE. As to any Revolving Credit Loan, its nature as a Prime Rate Loan or a
Eurodollar Rate Loan.

    UNANIMOUS BANK APPROVAL. The written consent of each Bank that is a party to
this Agreement at the time of reference.

    UNENCUMBERED ASSET. Any Real Estate Asset that on any date of determination
is not subject to any Liens (excluding (i) any such Lien imposed by the
organizational documents of the owner of such asset relating solely to a
restriction on the timing of any sale or refinancing of such Real Estate Asset
which does not materially and adversely

                                      -29-
<Page>

affect the value of such Real Estate Asset and with respect to which the Agent
has been specifically notified, and (ii) any Permitted Liens).

    UNIFORM CUSTOMS. With respect to any Letter of Credit, the Uniform Customs
and Practice for Documentary Credits (1993 Revision), International Chamber of
Commerce Publication No. 500, or any successor version thereof adopted by the
Agent in the ordinary course of its business as a letter of credit issuer and in
effect at the time of issuance of such Letter of Credit.

    UNSECURED CONSOLIDATED TOTAL INDEBTEDNESS. As of any date of determination,
the aggregate principal amount of Consolidated Total Indebtedness of the
Borrower and its Subsidiaries outstanding at such date (including, without
limitation, all the Obligations under this Agreement as of such date), that is
not secured by a Lien evidenced by a mortgage, deed of trust or other similar
security interest.

    UNRESTRICTED CASH AND CASH EQUIVALENTS. As of any date of determination, the
sum of (a) the aggregate amount of unrestricted cash then actually held by the
Borrower or any of its Subsidiaries (excluding without limitation, until
forfeited or otherwise entitled to be retained by the Borrower or any of its
Subsidiaries, tenant security and other restricted deposits) and (b) the
aggregate amount of unrestricted cash equivalents (valued at fair market value)
then held by the Borrower or any of its Subsidiaries. As used in this
definition, (i) "unrestricted" means the specified asset is not subject to any
Liens in favor of any Person, PROVIDED that, in any event, cash held in a
designated hotel account which is required to be used by the Borrower or any
Subsidiary in connection with such hotel shall be deemed to be unrestricted
cash, and (ii) "cash equivalents" means that such asset has a liquid, par value
in cash and is convertible to cash on demand. Notwithstanding anything contained
herein to the contrary, the term Unrestricted Cash and Cash Equivalents shall
not include the Commitments of the Banks to make Loans or to make any other
extension of credit under this Agreement.

    WHOLLY-OWNED SUBSIDIARY. Any Subsidiary which the Borrower shall at all
times own directly or indirectly (through a Subsidiary or Subsidiaries) at least
a majority (by number of votes or controlling interests) of the outstanding
voting interests and ninety-nine percent (99%) of the economic interests. For
purposes of this definition, (i) with respect to any Subsidiary of the Borrower
which is a Massachusetts nominee trust, references to such Subsidiary shall be
deemed to be references to the beneficiary or beneficiaries of such nominee
trust, and (ii) BPLP shall not be permitted to be released from its Obligations
as a Borrower hereunder, notwithstanding any provision of Section 8.14.

    "WITHOUT RECOURSE" or "WITHOUT RECOURSE". With reference to any obligation
or liability, any obligation or liability for which the obligor thereunder is
not liable or obligated other than as to its interest in a designated Real
Estate Asset or other specifically identified asset only, subject to such
limited exceptions to the non-recourse nature of such obligation or liability,
such as, but not limited to, fraud, misappropriation,

                                      -30-
<Page>

misapplication and environmental indemnities, as are usual and customary in like
transactions involving institutional lenders at the time of the incurrence of
such obligation or liability.

    Section 1.2.   RULES OF INTERPRETATION.

                        (i)    A reference to any document or agreement shall
                   include such document or agreement as amended, modified or
                   supplemented from time to time in accordance with its terms
                   or the terms of this Agreement.

                        (ii)   The singular includes the plural and the plural
                   includes the singular.

                        (iii)  A reference to any law includes any amendment or
                   modification to such law.

                        (iv)   A reference to any Person includes its permitted
                   successors and permitted assigns.

                        (v)    Accounting terms not otherwise defined herein
                   have the meanings assigned to them by generally accepted
                   accounting principles applied on a consistent basis by the
                   accounting entity to which they refer.

                        (vi)   The words "include", "includes" and "including"
                   are not limiting.

                        (vii)  All terms not specifically defined herein or by
                   generally accepted accounting principles, which terms are
                   defined in the Uniform Commercial Code as in effect in
                   Massachusetts, have the meanings assigned to them therein.

                        (viii) Reference to a particular "Section " refers to
                   that section of this Agreement unless otherwise indicated.

                        (ix)   The words "herein", "hereof", "hereunder" and
                   words of like import shall refer to this Agreement as a whole
                   and not to any particular section or subdivision of this
                   Agreement.

    Section 2.     THE REVOLVING CREDIT FACILITY.

    Section 2.1    COMMITMENT TO LEND. Subject to the provisions of Section 2.4
and the other terms and conditions set forth in this Agreement, each of the
Banks severally agrees to lend to the Borrower, and the Borrower may borrow,
repay, and reborrow from each Bank from time to time between the Closing Date
and the Maturity Date upon notice by the

                                      -31-
<Page>

Borrower to the Agent (with copies to the Agent for each Bank) given in
accordance with Section 2.4, such sums as are requested by the Borrower up to a
maximum aggregate principal amount outstanding (after giving effect to all
amounts requested) at any one time equal to such Bank's Commitment MINUS,
without double counting, an amount equal to such Bank's Commitment Percentage
MULTIPLIED BY the sum of (x) the outstanding principal amount of all Swingline
Loans and Bid Rate Loans PLUS (y) all Reimbursement Obligations to the extent
not yet deemed Revolving Credit Loans pursuant to Section 3.3 and the Maximum
Drawing Amount; PROVIDED that the sum of the outstanding amount of the Revolving
Credit Loans (after giving effect to all amounts requested), PLUS the Maximum
Drawing Amount and, without double-counting the portion, if any, of any Letter
of Credit which is drawn and included in the Revolving Credit Loans or the
Maximum Drawing Amount, all outstanding Reimbursement Obligations, PLUS all
outstanding Swingline Loans, PLUS all outstanding Bid Rate Loans, shall not at
any time exceed the lesser of (i) the Total Commitment and (ii) the Borrowing
Base Availability at such time, and PROVIDED, FURTHER, that at the time the
Borrower requests a Revolving Credit Loan and after giving effect to the making
thereof: (i) in the case of any borrowing, all of the conditions in Section 13
(and in the case of any initial borrowing or other extension of credit on the
Closing Date, also the conditions in Section 12) have been met at the time of
such request, and (ii) there has not occurred and is not continuing (or will not
occur by reason thereof) any Default or Event of Default; it being acknowledged
and agreed that the Borrower shall be permitted to request and borrow Loans if a
Non-Material Breach (rather than a Default or Event of Default) exists, PROVIDED
that in the event that such Non-Material Breach relates to a Real Estate Asset
forming part of the Borrowing Base at such time, such Real Estate Asset shall be
excluded from the calculation of Borrowing Base Availability for all purposes in
the compliance certificate accompanying any Completed Loan Request.

    The Revolving Credit Loans shall be made PRO RATA in accordance with each
Bank's Commitment Percentage. Each request for a Revolving Credit Loan made
pursuant to Section 2.4 shall constitute a representation and warranty by the
Borrower that the conditions set forth in Section 12 have been satisfied (except
to the extent any such condition has been waived and/or deferred in writing by
the Agent and the required number of Banks) as of the Closing Date and that the
conditions set forth in Section 13 have been satisfied (except to the extent any
such condition has been waived and/or deferred in writing by the Agent and the
required number of Banks) on the date of such request and will be satisfied
(except to the extent any such condition has been waived and/or deferred in
writing by the Agent and the required number of Banks) on the proposed Drawdown
Date of the requested Loan or issuance of Letter of Credit, as the case may be,
PROVIDED that the making of such representation and warranty by the Borrower
shall not limit the right of any Bank not to lend if such conditions have not
been met. No Revolving Credit Loan or other extension of credit shall be
required to be made by any Bank unless (in connection with the initial Revolving
Credit Loan or Letter of Credit or other extension of credit) all of the
conditions contained in Section 12 have been satisfied (except to the extent any
such condition has been waived and/or deferred in writing by the Agent and the
required

                                      -32-
<Page>

number of Banks) as of the Closing Date and unless all of the conditions set
forth in Section 13 have been met at the time of any request for a Revolving
Credit Loan or other extension of credit (except to the extent any such
condition has been waived and/or deferred in writing by the Agent and the
required number of Banks).

    Section 2.2.   THE REVOLVING CREDIT NOTES. The Revolving Credit Loans shall
be evidenced by the Revolving Credit Notes. A Revolving Credit Note shall be
payable to the order of each Bank in an aggregate principal amount equal to such
Bank's Commitment. The Borrower irrevocably authorizes each Bank to make or
cause to be made, at or about the time of the Drawdown Date of any Revolving
Credit Loan or at the time of receipt of any payment of principal on such Bank's
Revolving Credit Notes, an appropriate notation on such Bank's applicable Note
Record reflecting the making of such Revolving Credit Loan or (as the case may
be) the receipt of such payment. The outstanding amount of the Revolving Credit
Loans set forth on such applicable Note Record shall be PRIMA FACIE evidence of
the principal amount thereof owing and unpaid to such Bank, but the failure to
record, or any error in so recording, any such amount on such Note Record shall
not limit or otherwise affect the rights and obligations of the Borrower
hereunder or under any Revolving Credit Note to make payments of principal of or
interest on any Revolving Credit Note when due.

    Section 2.3.   INTEREST ON REVOLVING CREDIT LOANS; FEES.

                   (a) Each Prime Rate Loan shall bear interest for the period
commencing with the Drawdown Date thereof and ending on the last day of the
Interest Period with respect thereto (unless earlier paid in accordance with
Section 4.2) at a rate equal to the Prime Rate PLUS the Applicable Prime Rate
Margin.

                   (b) Each Eurodollar Rate Loan shall bear interest for the
period commencing with the Drawdown Date thereof and ending on the last day of
the Interest Period with respect thereto (unless earlier paid in accordance with
Section 4.2) at a rate equal to the Eurodollar Rate determined for such Interest
Period PLUS the Applicable Eurodollar Margin.

                   (c) The Borrower unconditionally promises to pay interest on
each Revolving Credit Loan in arrears on each Interest Payment Date with respect
thereto.

                   (d) The Borrower agrees to pay to the Agent, for the accounts
of the Banks in accordance with their respective Commitment Percentages, a
facility fee (the "Facility Fee") calculated at the rate, expressed in basis
points on the Total Commitment, which shall vary from time to time in
relationship to variances in the Debt Ratings as set forth in the following
table:

                                      -33-
<Page>

<Table>
<Caption>
    S&P                  Moody's                Facility Fee (bps)
    --------------       ------------           ------------------
    <S>                  <C>                    <C>
    A-or above           A3 or above            15

    BBB+                 Baa1                   15

    BBB                  Baa2                   20

    BBB-                 Baa3                   20

    Below BBB- or        Below Baa3 or
    unrated              unrated                25
</Table>

If the Debt Ratings from the two agencies referred to above are not equivalent,
the Facility Fee will be determined (i) based on the higher of the two Debt
Ratings if the lower Debt Rating is no more than one level lower than the higher
Debt Rating, and (ii) based on the average of the two Debt Ratings if the lower
Debt Rating is more than one level lower than the higher Debt Rating.
Adjustments in the Facility Fee based upon a change in a Debt Rating level shall
be effective on the first day following the change in such Debt Rating.

The Borrower shall notify the Agent in writing of any change in the Debt Rating
as and when such change occurs.

The Facility Fee shall be payable quarterly in arrears on the first Business Day
of each calendar quarter for the immediately preceding calendar quarter
commencing on the first such date following the Closing Date through the
Maturity Date, with a final payment on the Maturity Date.

    Section 2.4.   REQUESTS FOR REVOLVING CREDIT LOANS.

    The following provisions shall apply to each request by the Borrower for a
Revolving Credit Loan:

                            (i)   The Borrower shall submit a Completed Loan
                   Request to the Agent, together with a duplicate copy of such
                   Completed Loan Request for each Bank which is then a party to
                   this Agreement at the time such loan request is made. Such
                   Completed Loan Requests shall be delivered in separate
                   envelopes to the Agent and be addressed to the Agent and each
                   Bank, respectively, and each such envelope shall be
                   conspicuously marked with the following legend: "LOAN REQUEST
                   -- TIME SENSITIVE -- MUST RESPOND WITHIN [2/4] DAYS" and with
                   the appropriate period filled in. Except as otherwise
                   provided herein, each Completed Loan Request shall be in a
                   minimum amount of $1,000,000 or an integral multiple of
                   $100,000 in excess thereof. Each Completed Loan Request shall
                   be irrevocable and binding on the Borrower and shall obligate
                   the Borrower to accept the Revolving Credit Loans requested

                                      -34-
<Page>

                   from the Banks on the proposed Drawdown Date, unless such
                   Completed Loan Request is withdrawn (x) in the case of a
                   request for a Eurodollar Rate Loan, at least four (4)
                   Business Days prior to the proposed Drawdown Date for such
                   Loan, and (y) in the case of a request for a Prime Rate Loan,
                   at least two (2) Business Days prior to the proposed Drawdown
                   Date for such Loan.

                            (ii)  Each Completed Loan Request shall be delivered
                   by the Borrower to the Agent by 10:00 a.m. on any Business
                   Day, and at least two (2) Business Days prior to the proposed
                   Drawdown Date of any Prime Rate Loan, and at least four (4)
                   Business Days prior to the proposed Drawdown Date of any
                   Eurodollar Rate Loan.

                            (iii) Each Completed Loan Request shall include a
                   completed writing in the form of EXHIBIT B hereto specifying:
                   (1) the principal amount of the Revolving Credit Loan
                   requested, (2) the proposed Drawdown Date of such Revolving
                   Credit Loan, (3) the Interest Period applicable to such
                   Revolving Credit Loan, and (4) the Type of such Revolving
                   Credit Loan being requested.

                            (iv)  No Bank shall be obligated to fund any
                   Revolving Credit Loan or issue any Letter of Credit unless:

                                  (a) a Completed Loan Request has been timely
                        received by the Agent as provided in subsection (i)
                        above; and

                                  (b) both before and after giving effect to the
                        Revolving Credit Loan to be made or Letter of Credit to
                        be issued pursuant to the Completed Loan Request, all of
                        the conditions contained in Section 12 shall have been
                        satisfied (to the extent such conditions have not been
                        waived and/or deferred in writing by the Agent and the
                        required number of Banks prior to the initial advance)
                        as of the Closing Date, with respect to the initial
                        advance only, and all of the conditions set forth in
                        Section 13 shall have been met, including, without
                        limitation, the condition under Section 13.1 that there
                        be no Default or Event of Default under this Agreement;
                        and

                                  (c) the Agent shall have received (with copies
                        to the Agent for each Bank) a certificate in the form of
                        EXHIBIT C-1 hereto signed by the chief financial
                        officer, treasurer or controller of the Borrower setting
                        forth computations evidencing compliance with the
                        covenants contained in Section 10 on a PRO FORMA basis
                        after giving effect to such requested Revolving Credit
                        Loan (including, without limitation, a certification
                        that, to the best of the Borrower's

                                      -35-
<Page>

                        knowledge, if the Borrowing Base Value and the Borrowing
                        Base Debt Service Coverage Ratio were to be calculated
                        on the Drawdown Date of any Revolving Credit Loan for
                        the period through the Drawdown Date rather than through
                        the last day of the most recently completed fiscal
                        quarter, there would be sufficient Borrowing Base
                        Availability for the requested Revolving Credit Loan),
                        and certifying that, both before and after giving effect
                        to such requested Revolving Credit Loan or Letter of
                        Credit, no Default or Event of Default exists or will
                        exist under this Agreement or any other Loan Document,
                        and that after taking into account such requested
                        Revolving Credit Loan or Letter of Credit, no Default or
                        Event of Default will exist as of the Drawdown Date.

                            (v) The Agent will use best efforts to cause the
                   Completed Loan Request to be delivered to each Bank on the
                   same day it is received by the Agent and will, absent
                   circumstances outside of its control, cause the Completed
                   Loan Request to be delivered to each Bank on the Business Day
                   following the day a Completed Loan Request is received by the
                   Agent.

    Section 2.5.   CONVERSION OPTIONS.

                   (a) The Borrower may elect from time to time to convert any
outstanding Revolving Credit Loan to a Revolving Credit Loan of another Type,
PROVIDED that (i) with respect to any such conversion of a Eurodollar Rate Loan
to a Prime Rate Loan, such conversion shall take place automatically at the end
of the applicable Interest Period unless the Borrower provides notice to the
Agent of its request to continue such Loan as a Eurodollar Rate Loan as provided
in Section 2.5(b) and Section 2.5(a)(ii); (ii) subject to the further proviso at
the end of this Section 2.5(a) and subject to Section 2.5(b) and Section 2.5(d),
with respect to any conversion of a Prime Rate Loan to a Eurodollar Rate Loan
(or a continuation of a Eurodollar Rate Loan, as provided in Section 2.5(b)),
the Borrower shall give the Agent (with copies to the Agent for each Bank) at
least four (4) Eurodollar Business Days' prior written notice of such election,
which such notice must be received by the Agent by 10:00 a.m. on any Business
Day; and (iii) no Loan may be converted into a Eurodollar Rate Loan when any
Default or Event of Default has occurred and is continuing. All or any part of
outstanding Revolving Credit Loans of any Type may be converted as provided
herein, PROVIDED that each Conversion Request relating to the conversion of a
Prime Rate Loan to a Eurodollar Rate Loan shall be for an amount equal to
$1,000,000 or an integral multiple of $100,000 in excess thereof and shall be
irrevocable by the Borrower.

                   (b) Any Revolving Credit Loan of any Type may be continued as
such upon the expiration of the Interest Period with respect thereto (i) in the
case of Prime Rate Loans, automatically and (ii) in the case of Eurodollar Rate
Loans by compliance by the Borrower with the notice provisions contained in
Section 2.5(a)(ii); PROVIDED that no Eurodollar

                                      -36-
<Page>

Rate Loan may be continued as such when any Default or Event of Default has
occurred and is continuing but shall be automatically converted to a Prime Rate
Loan on the last day of the first Interest Period relating thereto ending during
the continuance of any Default or Event of Default. The Borrower shall notify
the Agent promptly when any such automatic conversion contemplated by this
Section 2.5(b) is scheduled to occur.

                   (c) In the event that the Borrower does not notify the Agent
of its election hereunder with respect to any Revolving Credit Loan, such Loan
shall be automatically converted to a Prime Rate Loan at the end of the
applicable Interest Period.

                   (d) The Borrower may not request or elect a Eurodollar Rate
Loan pursuant to Section 2.4, elect to convert a Prime Rate Loan to a Eurodollar
Loan pursuant to Section 2.5(a) or elect to continue a Eurodollar Rate Loan
pursuant to Section 2.5(b) if, after giving effect thereto, there would be
greater than six (6) Eurodollar Rate Loans then outstanding. Any Loan Request or
Conversion Request for a Eurodollar Rate Loan that would create greater than six
(6) Eurodollar Rate Loans outstanding shall be deemed to be a Loan Request or
Conversion Request for a Prime Rate Loan. By way of explanation of the
foregoing, in the event that the Borrower wishes to convert or continue two or
more Loans into one Eurodollar Rate Loan on the same day and for identical
Interest Periods (or borrow an additional Revolving Credit Loan simultaneously
with converting or continuing a Revolving Credit Loan for identical Interest
Periods), such Eurodollar Rate Loan shall constitute one single Eurodollar Rate
Loan for purposes of this clause (d).

    Section 2.6.   FUNDS FOR REVOLVING CREDIT LOANS.

                   (a) Subject to the other provisions of this Section 2, not
later than 11:00 a.m. (Boston time) on the proposed Drawdown Date of any
Revolving Credit Loan, each of the Banks will make available to the Agent, at
its Head Office, in immediately available funds, the amount of such Bank's
Commitment Percentage of the amount of the requested Revolving Credit Loan. Upon
receipt from each Bank of such amount, the Agent will make available to the
Borrower the aggregate amount of such Revolving Credit Loan made available to
the Agent by the Banks. All such funds received by the Agent by 11:00 a.m.
(Boston Time) on any Business Day will be made available to the Borrower not
later than 2:00 p.m. on the same Business Day; funds received after such time
will be made available by not later than 11:00 a.m. on the next Business Day
(provided that as to any Bank which is required to fund Revolving Credit Loans
from its head office located in the Pacific Time Zone (U.S.), the preceding
reference to `11:00 a.m.' shall be deemed to be a reference to `1:00 p.m.'). The
failure or refusal of any Bank to make available to the Agent at the aforesaid
time and place on any Drawdown Date the amount of its Commitment Percentage of
the requested Revolving Credit Loan shall not relieve any other Bank from its
several obligation hereunder to make available to the Agent the amount of its
Commitment Percentage of any requested Revolving Credit Loan but in no event
shall the Agent (in its capacity as Agent) have any obligation to make any
funding or shall any Bank be obligated to fund more than its Commitment
Percentage of the

                                      -37-
<Page>

requested Revolving Credit Loan or to increase its Commitment Percentage on
account of such failure or otherwise.

                   (b) The Agent may, unless notified to the contrary by any
Bank prior to a Drawdown Date, assume that such Bank has made available to the
Agent on such Drawdown Date the amount of such Bank's Commitment Percentage of
the Revolving Credit Loan to be made on such Drawdown Date, and the Agent may
(but it shall not be required to), in reliance upon such assumption, make
available to the Borrower a corresponding amount. If any Bank makes available to
the Agent such amount on a date after such Drawdown Date, such Bank shall pay to
the Agent on demand an amount equal to the product of (i) the average, computed
for the period referred to in clause (iii) below, of the weighted average
interest rate paid by the Agent for federal funds acquired by the Agent during
each day included in such period, MULTIPLIED BY (ii) the amount of such Bank's
Commitment Percentage of such Revolving Credit Loan, MULTIPLIED BY (iii) a
fraction, the numerator of which is the number of days that elapsed from and
including such Drawdown Date to the date on which the amount of such Bank's
Commitment Percentage of such Revolving Credit Loan shall become immediately
available to the Agent, and the denominator of which is 365. A statement of the
Agent submitted to such Bank with respect to any amounts owing under this
paragraph shall be PRIMA FACIE evidence of the amount due and owing to the Agent
by such Bank.

    Section 2.7.   REDUCTION OF COMMITMENT. The Borrower shall have the right at
any time and from time to time upon five (5) Business Days' prior written notice
to the Agent (with copies to the Agent for each Bank) to reduce by $500,000 or
an integral multiple thereof or terminate entirely the unborrowed portion of the
then Total Commitment, whereupon the Commitments of the Banks shall be reduced
PRO RATA in accordance with their respective Commitment Percentages by the
amount specified in such notice or, as the case may be, terminated. Upon the
effective date of any such reduction or termination, the Borrower shall pay to
the Agent for the respective accounts of the Banks the full amount of the
Facility Fee then accrued and unpaid on the amount of the reduction. No
reduction or termination of the Commitments may be reinstated.

    Section 2.8.   SWINGLINE LOANS.

                   (a) AVAILABILITY. Subject to the terms and conditions of this
Agreement and so long as the Swingline Lender does not have knowledge that any
Default or Event of Default exists or will exist after giving effect to the
applicable Swingline Loan, and the Borrower has delivered to the Agent a loan
request, including the certificate referred to in Section 2.4(iv)(c), as if all
references in Section 2.4(iv)(c) to Revolving Credit Loans were to Swingline
Loans, the Swingline Lender agrees to make Swingline Loans to the Borrower from
time to time from the Closing Date to, but not including, the Swingline
Termination Date; PROVIDED, that the aggregate principal amount of all
outstanding Swingline Loans (after giving effect to any amount requested) at any
time, shall not exceed the lesser of (i) the Total Commitment in effect at such
time LESS the sum

                                      -38-
<Page>

of (A) all outstanding Revolving Credit Loans at such time (after giving effect
to all amounts requested), (B) the Maximum Drawing Amount and, without
double-counting the portion, if any, of any Letter of Credit which is drawn and
included in the Revolving Credit Loans or the Maximum Drawing Amount, all
outstanding Reimbursement Obligations at such time, and (C) all outstanding Bid
Rate Loans at such time, (ii) the Borrowing Base Availability at such time and
(iii) the Swingline Commitment at such time. Swingline Loans hereunder may be
used in anticipation of borrowing Revolving Credit Loans, Bid Rate Loans and for
other short-term requirements and shall be repaid in accordance with the terms
hereof. Each Swingline Loan must be for an amount equal to at least $1,000,000
and in an integral multiple of $100,000 and shall be evidenced by the Swingline
Note. The Swingline Lender shall initiate the transfer of funds representing the
Swingline Loan to the Borrower by 4:00 p.m. (Boston time) on the Business Day of
the requested borrowing, so long as the Swingline Loan has been requested by the
Borrower no later than 1:00 p.m. (Boston time) on such Business Day. In no event
shall the number of Swingline Loans outstanding at any time exceed three (3).
All Swingline Loans shall bear interest at the Prime Rate plus the Applicable
Prime Rate Margin. The Borrower unconditionally promises to pay interest on each
Swingline Loan in arrears on each Interest Payment Date with respect thereto.

                   (b) REPAYMENT. The Borrower hereby absolutely and
unconditionally promises to repay the outstanding principal amount of each
Swingline Loan and all accrued interest and charges thereon (the "Swingline Loan
Amount") on the earliest to occur of: (i) the fifth (5th) Business Day after the
date on which the Swingline Loan is advanced or (ii) the Swingline Termination
Date; PROVIDED, the Borrower shall have the right to prepay Swingline Loans
without penalty or any prepayment charge.

                   (c) REFUNDING AND CONVERSION OF SWINGLINE LOANS TO REVOLVING
CREDIT LOANS.

                       (i)   On the maturity of each Swingline Loan (which shall
be no longer than the period for repayment set forth above in Section 2.8(b)),
the Borrower shall be deemed to have requested on such date a Revolving Credit
Loan comprised solely of a Prime Rate Loan in a principal amount equal to the
Swingline Loan Amount in order to repay such Swingline Loan. Such refundings of
the Swingline Loan through the funding of such Revolving Credit Loans shall be
made by the Banks in accordance with their respective Commitment Percentages and
shall thereafter be reflected as Revolving Credit Loans of the Banks on the
books and records of the Agent.

                       (ii)  If a Default or an Event of Default has occurred
and is continuing, all Swingline Loans shall be refunded by the Banks on demand
by the Swingline Lender, in which case the Borrower shall be deemed to have
requested on such date of demand a Revolving Credit Loan comprised solely of a
Prime Rate Loan in a principal amount equal to the Swingline Loan Amount for
such Swingline Loans. Such refundings of the Swingline Loans through the funding
of such Revolving Credit Loans

                                      -39-
<Page>

shall be made by the Banks in accordance with their respective Commitment
Percentages and shall thereafter be reflected as Revolving Credit Loans of the
Banks on the books and records of the Agent.

                       (iii) Each Bank shall fund its respective Commitment
Percentage of Revolving Credit Loans as required to so repay Swingline Loans
outstanding to the Swingline Lender upon such deemed request or demand by the
Swingline Lender but in no event later than 2:00 p.m. (Boston time) on the next
succeeding Business Day after such deemed request or demand is made. No Bank's
obligation to fund its respective Commitment Percentage of the repayment of a
Swingline Loan shall be affected by any other Bank's failure to fund its
Commitment Percentage of such repayment, nor shall any Bank's Commitment
Percentage be increased as a result of any such failure of any other Bank to
fund its Commitment Percentage. To the extent any Bank does not fund its
respective Commitment Percentage of any Revolving Credit Loan to the Borrower
pursuant to this Section 2.8(c)(iii), such Bank shall be deemed a Delinquent
Bank and the Borrower shall repay such amounts to the Swingline Lender in
accordance with the provisions of Section 4.3 as if such Loan were a Revolving
Credit Loan for which a Bank did not remit its share to the Agent. If any
portion of any such amount paid to the Swingline Lender shall be recovered by or
on behalf of the Borrower from the Swingline Lender in bankruptcy or otherwise,
the loss of the amount so recovered shall be ratably shared among all the Banks.

                       (iv)  If at any time the Borrower receives notice from
the Swingline Lender that the aggregate principal amount of all Revolving Credit
Loans outstanding, PLUS the aggregate principal amount of all Swingline Loans
outstanding (including the Swingline Loan for which demand for payment is then
made by the Swingline Lender pursuant to this subsection), PLUS the Maximum
Drawing Amount and, PLUS, without double-counting the portion, if any, of any
Letter of Credit which is drawn and included in the Revolving Credit Loans or
the Maximum Drawing Amount, all outstanding Reimbursement Obligations at such
time, PLUS all outstanding Bid Rate Loans at such time, equals or exceeds the
lesser of (A) Total Commitment at such time and (B) the Borrowing Base
Availability at such time, the Borrower shall repay the amount of such excess
upon demand by the Swingline Lender, which payment shall be applied first to the
Swingline Loans, second to the Revolving Credit Loans and thereafter to the Bid
Rate Loans.

                       (v)   Each Bank acknowledges and agrees that its
obligation to refund Swingline Loans with Revolving Credit Loans in accordance
with the terms of this Section 2.8 is absolute and unconditional and shall not
be affected by any circumstance whatsoever, including, in any event,
non-satisfaction of any conditions set forth in this Agreement pertaining to
advances of Revolving Credit Loans hereunder, except to the limited extent
expressly referred to in the first sentence of Section 2.8(a). Further, each
Bank agrees and acknowledges that if, prior to the refunding of any outstanding
Swingline Loans pursuant to this Section 2.8, one of the events described in
Sections 14.1(g) or (h) shall have

                                      -40-
<Page>

occurred, each Bank will, on the date the applicable Revolving Credit Loan would
have been made pursuant to Section 2.8(c)(i) or (ii), purchase an undivided
participating interest in the Swingline Loan to be refunded in an amount equal
to its Commitment Percentage of such Swingline Loan Amount. Each Bank will
immediately transfer to the Swingline Lender, in immediately available funds,
the amount of its participation. Whenever, at any time after the Swingline
Lender has received from any Bank such Bank's participating interest in a
Swingline Loan, the Swingline Lender receives any payment on account thereof,
the Swingline Lender will distribute to such Bank its participating interest in
such amount (appropriately adjusted, in the case of interest payments, to
reflect the period of time during which such Bank's participating interest was
outstanding and funded).

                       (vi)  Each Bank's Commitment Percentage applicable to any
Swingline Loan shall be identical to its Commitment Percentage applicable to
Revolving Credit Loans.

    Section 2.9.   BID RATE ADVANCES.

                   (a) Each Bank severally agrees that, on the terms and
conditions set forth in this Agreement, the Borrower may request and receive Bid
Rate Advances under this Section 2.9 from time to time on any Business Day
during the period from the date hereof until the date occurring 30 days prior to
the Maturity Date in the manner set forth below; PROVIDED, HOWEVER, that:

                       (i)   following the making of each Bid Rate Advance, the
                   aggregate principal amount of all Revolving Credit Loans then
                   outstanding, PLUS the aggregate amount of all Swingline Loans
                   then outstanding, PLUS the aggregate amount of all Bid Rate
                   Advances then outstanding (including the requested Bid Rate
                   Advance), PLUS the Maximum Drawing Amount and, without
                   double-counting the portion, if any, of any Letter of Credit
                   which is drawn and included in the Revolving Credit Loans or
                   the Maximum Drawing Amount, PLUS all outstanding
                   Reimbursement Obligations at such time, shall not exceed the
                   lesser of (A) the Total Commitment in effect at such time or
                   (B) the Borrowing Base Availability in effect at such time;

                       (ii)  at no time shall the aggregate amount of all Bid
                   Rate Advances then outstanding (including the requested Bid
                   Rate Advance) exceed the Bid Rate Maximum Amount; and

                       (iii) at the time the Borrower requests a Bid Rate
                   Advance and after giving effect to the making thereof, no
                   Default or Event of Default has occurred and is continuing.

                                      -41-
<Page>

                   (b) The procedures for the solicitation and acceptance of Bid
Rate Loans are set forth below (with the references to time of day meaning
Boston, Massachusetts time):

                       (i)   The Borrower may request a Bid Rate Advance under
                   this Section 2.9(b) by giving the Agent irrevocable notice,
                   in the form attached hereto as Exhibit D-2 (a "Bid Rate
                   Advance Borrowing Notice"), specifying the date and aggregate
                   amount of the proposed Bid Rate Advance, the maturity date
                   for repayment of each Bid Rate Loan to be made as part of
                   such Bid Rate Advance (which maturity date may not be earlier
                   than, in the case of an Absolute Rate Auction, the date
                   occurring one day, and in the case of an Indexed Rate
                   Auction, the date occurring seven days, after the date of the
                   related Bid Rate Advance or later than, in either case, the
                   earlier of the day occurring 180 days after the date of such
                   Bid Rate Advance and the Maturity Date), and any other terms
                   to be applicable to such Bid Rate Advance, not later than
                   11:00 a.m. (A) in the case of an Absolute Rate Auction, one
                   (1) Business Day prior to the date of the proposed Bid Rate
                   Advance, and (B) in the case of an Indexed Rate Auction, four
                   (4) Business Days prior to the date of the proposed Bid Rate
                   Advance. The Agent shall, promptly following its receipt of a
                   Bid Rate Advance Borrowing Notice under this Section 2.9(b),
                   notify each Bank of such request by sending such Bank a copy
                   of such Bid Rate Advance Borrowing Notice.

                       (ii)  Each Bank may, if, in its sole discretion, it
                   elects to do so, irrevocably offer to make one or more Bid
                   Rate Loans to the Borrower as part of such proposed Bid Rate
                   Advance at a rate or rates of interest specified by such Bank
                   in its sole discretion, by providing written notice to the
                   Agent (which shall give prompt notice thereof to the
                   Borrower), before 12:00 p.m. (or if such Bank is serving as
                   the Agent, before 11:30 a.m.) on (A) the date of such
                   proposed Bid Rate Advance, in the case of an Absolute Rate
                   Auction, and (B) the date that is three Business Days before
                   the date of such proposed Bid Rate Advance, in the case of an
                   Indexed Rate Auction, in the form of Exhibit D-3 attached
                   hereto (the "Competitive Bid Notice") of the minimum amount
                   and maximum amount of each Bid Rate Loan which such Bank
                   would be willing to make as part of such proposed Bid Rate
                   Advance (which amounts may, subject to the proviso to the
                   first sentence of Section 2.9(a), exceed such Bank's
                   Commitment) and the rate or rates of interest therefor.

                       Any Competitive Bid Notice shall be disregarded and given
                   no effect if it contains qualifying or conditional language,
                   proposes terms and conditions other than or in addition to
                   those set forth in the applicable Bid

                                      -42-
<Page>

                   Rate Advance Borrowing Notice or arrives after the time set
                   forth above for its receipt by the Agent.

                       (iii) The Borrower shall, in turn, before (A) 1:00 p.m.
                   on the date of such proposed Bid Rate Advance, in the case of
                   an Absolute Rate Auction, and (B) 1:00 p.m. three Business
                   Days before the date of such proposed Bid Rate Advance, in
                   the case of an Indexed Rate Auction, either:

                             (x) cancel such Bid Rate Advance by giving the
                       Agent notice to that effect, or

                             (y) accept one or more of the offers made by any
                       Bank or Banks pursuant to Section 2.9(b), in its sole
                       discretion and subject to Section 2.9(d), by giving
                       notice, in the form of EXHIBIT D-4 attached hereto, to
                       the Agent of the amount of each Bid Rate Loan to be made
                       by each Bank as part of such Bid Rate Advance, and reject
                       any remaining offers made by Banks pursuant to Section
                       2.9(b)(ii) by giving the Agent notice to that effect.

                       (iv)  If the Borrower notifies the Agent that such Bid
                   Rate Advance is canceled pursuant to Section 2.9(b)(iii)(x)
                   above, the Agent shall give prompt notice thereof to the
                   Banks and such Bid Rate Advance shall not be made.

                       (v)   If the Borrower accepts one or more of the offers
                   made by any Bank or Banks pursuant to Section 2.9(b)(iii)(y),
                   the Agent shall in turn promptly notify (A) each Bank that
                   has made an offer as described in Section 2.9(b)(ii) of the
                   date, and aggregate amount of such Bid Rate Advance and
                   whether or not any offer or offers made by such Bank pursuant
                   to Section 2.9(b)(ii) have been accepted by the Borrower and
                   (B) each Bank that is to make a Bid Rate Loan as part of such
                   Bid Rate Advance, of the amount of each Bid Rate Loan to be
                   made by such Bank as part of such Bid Rate Advance. Each Bank
                   that is to make a Bid Rate Loan as part of such Bid Rate
                   Advance shall, not later than the specified remittance time
                   (as set forth in the notice received from the Agent pursuant
                   to clause (B) of the preceding sentence) on the date of such
                   Bid Rate Advance specified in the notice received from the
                   Agent pursuant to clause (B) of the preceding sentence, make
                   available to the Agent such Bank's portion of such Bid Rate
                   Advance, in same day funds. After receipt by the Agent of
                   such funds and provided that the conditions in Section 13 are
                   satisfied and the Borrower has delivered to the Agent the
                   certificate referred to in Section 2.4(iv)(c) as if all
                   references in Section 2.4(iv)(c) to Revolving Credit Loans
                   were to Bid Rate Loans, the Agent will make such funds
                   available to the

                                      -43-
<Page>

                   Borrower upon execution and delivery to the applicable Bank
                   (with a copy to the Agent) by the Borrower of a Bid Rate Note
                   evidencing such Bid Rate Loan (and the provisions set forth
                   in the last two sentences of Section 2.2 relating to
                   Revolving Credit Notes shall apply equally to the Bid Rate
                   Notes). Promptly after each Bid Rate Advance the Agent will
                   notify each Bank of the Bid Rate Advance.

                       (vi)  If the Borrower accepts one or more of the offers
                   made by any Bank or Banks pursuant to Section 2.9(b)(iii)(y)
                   and fails to borrow any Bid Rate Loan so accepted, the
                   Borrower shall indemnify the Bank funding such Loan against
                   any loss or expense incurred by reason of the liquidation or
                   reemployment of deposits or other funds acquired by such Bank
                   to fund or maintain such unborrowed Bid Rate Loans,
                   including, without limitation, Eurodollar Breakage Costs or
                   other compensation as provided in Section 5.8.

                       (vii) A Bid Rate Advance fee of $750.00 shall be payable
                   by the Borrower to the Agent, for the account of the Agent,
                   with respect to and concurrently with the delivery of each
                   Bid Rate Advance Borrowing Notice.

                   (c) Each Bid Rate Advance shall be in an aggregate amount not
less than $5,000,000 or an integral multiple of $1,000,000 in excess thereof,
and, following the making of each Bid Rate Advance, the Borrower shall be in
compliance with the limitation set forth in the proviso to Section 2.9(a).

                   (d) Each acceptance by the Borrower pursuant to Section
2.9(b)(iii)(y) of the offers made in response to a Bid Rate Advance Borrowing
Notice shall be treated as an acceptance of such offers in ascending order of
the rates or margins, as applicable, at which the same were made but if, as a
result thereof, two or more offers at the same such rate or margin would be
partially accepted, then the amounts of the Bid Rate Loans in respect of which
such offers are accepted shall be treated as being the amounts which bear the
same proportion to one another as the respective amounts of the Bid Rate Loans
so offered bear to one another but, in each case, rounded as the Agent may
consider necessary to ensure that the amount of each such Bid Rate Loan is
$5,000,000 or an integral multiple of $1,000,000 in excess thereof.

                   (e) Within the limits and on the conditions set forth in this
Section 2.9, the Borrower may from time to time borrow under this Section 2.9,
repay pursuant to Section 2.9(f), and reborrow under this Section 2.9.

                   (f) The Borrower hereby absolutely and unconditionally
promises to pay to the Agent for the account of each Bank which has made a Bid
Rate Loan to it, on the maturity date of such Bid Rate Loan (such maturity date
being that specified by the

                                      -44-
<Page>

Borrower for repayment of such Bid Rate Loan in the related Bid Rate Advance
Borrowing Notice) or such earlier date to which the maturity of such Bid Rate
Loan has been accelerated hereunder, the then unpaid principal amount of such
Bid Rate Loan and all accrued but unpaid interest thereon. The Borrower shall
have no right to prepay any principal amount of any Bid Rate Loan unless, and
then only on the terms, specified by the Borrower for such Bid Rate Loan in the
related Bid Rate Advance Borrowing Notice and subject to payment of Eurodollar
Breakage Costs and Section 5.8.

                   (g) The Borrower shall, and hereby absolutely and
unconditionally promises to, pay interest on the unpaid principal amount of each
Bid Rate Loan made to it, from the date of such Bid Rate Loan to the date the
principal amount of such Bid Rate Loan is repaid in full, at the rate of
interest for such Bid Rate Loan specified by the Bank making such Bid Rate Loan
in the related notice submitted by such Bank pursuant to Section 2.9(b)(ii),
payable on the interest payment date or dates specified by the Borrower for such
Bid Rate Loan in the related Bid Rate Advance Borrowing Notice and on any date
on which such Bid Rate Loan is prepaid, whether by acceleration or otherwise,
and at maturity. In the event the term of any Bid Rate Loan shall be longer than
three months, interest thereon shall be payable not less frequently than once
each three-month period during such term. Interest on Bid Rate Loans shall be
calculated for actual days elapsed on the basis of a 360-day year.

    Section 2.10.  INCREASES IN TOTAL COMMITMENT. The Borrower shall have the
right to cause the Total Commitment to increase by an amount not at any time
exceeding $200,000,000 (the "Increase"), in which event the Agent will amend
SCHEDULE 2 to reflect the increased Commitment of each Bank, if any, that has
agreed in writing to an increase and to add any third party financial
institution that may have become a party to, and a "Bank" under, this Agreement
in connection with the Increase; PROVIDED, HOWEVER, that it shall be a condition
precedent to the effectiveness of the Increase that the Increase Conditions
shall have been satisfied. In the event that the Increase results in any change
to the Commitment Percentage of any Bank, then on the effective date of such
Increase in the Total Commitment (i) any new Bank, and any existing Bank whose
Commitment has increased, shall pay to the Agent such amounts as are necessary
to fund its new or increased Commitment Percentage of all existing Revolving
Credit Loans, (ii) the Agent will use the proceeds thereof to pay to all Banks
whose Commitment Percentage is decreasing such amounts as are necessary so that
each such Bank's participation in existing Revolving Credit Loans will be equal
to its adjusted Commitment Percentage, and (iii) if the effective date of such
Increase in the Total Commitment occurs on a date other than the last day of an
Interest Period applicable to any outstanding Eurodollar Rate Loan, the Borrower
will be responsible for Eurodollar Breakage Costs and any other amounts payable
pursuant to Section 5.8 on account of the payments made pursuant to clause (ii)
above.

                                      -45-
<Page>

    Section 2.11.  EXTENSION OF REVOLVING CREDIT MATURITY DATE. At least 30 days
but in no event more than 90 days prior to January 17, 2006, the Borrower, by
written notice to the Agent (with copies for each Bank), may request an
extension of the Maturity Date by a period of one year from the Maturity Date
then in effect (the "Extension"). The Extension shall become effective on
January 17, 2006 so long as (i) the Borrower has paid to the Agent on such date,
for the ratable accounts of the Banks, an extension fee in an amount equal to 20
basis points on the Total Commitment in effect on such date, and (ii) no Default
or Event of Default has occurred and is continuing on such date and all
representations and warranties contained in the Loan Documents shall be true and
correct as of such date (except (i) to the extent of changes resulting from
transactions contemplated or not prohibited by this Agreement or the other Loan
Documents (including, without limitation, the fact that a Real Estate Asset may
cease to be a Borrowing Base Property pursuant to the terms of this Agreement)
and changes occurring in the ordinary course of business, (ii) to the extent
that such representations and warranties relate expressly to an earlier date and
(iii) to the extent otherwise represented by the Borrower with respect to the
representation set forth in Section 7.10). The notice referred to in the first
sentence of this Section 2.11 shall constitute and shall be deemed to be a
certification by the Borrower as to the truth and accuracy of the statements
contained in clause (ii) of the preceding sentence.

    Section 3.     LETTERS OF CREDIT.

    Section 3.1.   LETTER OF CREDIT COMMITMENTS.

                   Section 3.1.1. COMMITMENT TO ISSUE LETTERS OF CREDIT. Subject
to the terms and conditions hereof and the execution and delivery by the
Borrower of a letter of credit application on the Fronting Bank's customary form
as part of a Completed Loan Request (a "Letter of Credit Application"), the
Fronting Bank on behalf of the Banks and in reliance upon the agreement of the
Banks set forth in Section 3.1.4 and upon the representations and warranties of
the Borrower contained herein, agrees, in its individual capacity, to issue,
extend and renew for the account of the Borrower one or more letters of credit
(individually, a "Letter of Credit"), in such form as may be requested from time
to time by the Borrower and reasonably agreed to by the Fronting Bank; PROVIDED,
HOWEVER, that, after giving effect to such Completed Loan Request, (a) the
Maximum Drawing Amount plus all Reimbursement Obligations (to the extent, if
any, not yet deemed a Revolving Credit Loan pursuant to Section 3.3), shall not
exceed $100,000,000 at any one time and (b) the sum of (i) the Maximum Drawing
Amount and, without double counting, all Reimbursement Obligations (to the
extent, if any, not yet deemed a Revolving Credit Loan pursuant to Section 3.3)
and (ii) the amount of all Loans (including Swingline Loans and Bid Rate Loans)
outstanding shall not exceed the lesser of (x) the Total Commitment in effect at
such time and (y) the Borrowing Base Availability at such time.

                   Section 3.1.2. LETTER OF CREDIT APPLICATIONS. Each Letter of
Credit Application shall be completed to the reasonable satisfaction of the
Agent and the Fronting Bank. In

                                      -46-
<Page>

the event that any provision of any Letter of Credit Application shall be
inconsistent with any provision of this Agreement (including provisions
applicable to a Completed Loan Request) or shall impose additional financial or
other material obligations (other than technical, administrative and ministerial
obligations, whether relating to the mechanics of a draw under a Letter of
Credit or otherwise), then the provisions of this Agreement shall, to the extent
of any such inconsistency or additional material obligation, govern.

                   Section 3.1.3. TERMS OF LETTERS OF CREDIT. Each Letter of
Credit issued, extended or renewed hereunder shall, among other things, (i)
provide for the payment of sight drafts for honor thereunder when presented in
accordance with the terms thereof and when accompanied by the documents
described therein, and (ii) have an expiry date no later than the date which is
fourteen (14) days prior to the Maturity Date. Each Letter of Credit so issued,
extended or renewed shall be subject to the Uniform Customs.

                   Section 3.1.4. OBLIGATIONS OF BANKS WITH RESPECT TO LETTERS
OF CREDIT. Each Bank severally agrees that it shall be absolutely liable,
without regard to the occurrence of any Default or Event of Default or any other
condition precedent whatsoever, to the extent of such Bank's Commitment
Percentage, to reimburse the Fronting Bank on demand pursuant to Section 3.3 for
the amount of each draft paid by the Fronting Bank under each Letter of Credit
to the extent that such amount is not reimbursed by the Borrower pursuant to
Section 3.2 (such agreement for a Bank being called herein the "Letter of Credit
Participation" of such Bank). Each such payment made by a Bank shall be treated
as a purchase by such Bank of a participation in the Fronting Bank's interest in
such Letter of Credit and each Bank shall share, in accordance with its
respective Commitment Percentage, in any interest which accrues and is payable
by the Borrower pursuant to Section 3.2 or otherwise in connection with such
Letter of Credit.

                   Section 3.1.5. FRONTING BANK. Notwithstanding the definition
of Fronting Bank, in the event that the Borrower reasonably determines that it
would be beneficial to have a Letter of Credit issued by a Bank with a higher
rating than Fleet has at any applicable time of reference (as determined by
Moody's or S&P), or for any other reason acceptable to the Agent, the Borrower
shall have the right to elect any Bank having a higher rating than Fleet (or
such other applicable Bank) as the Fronting Bank for that particular Letter of
Credit, PROVIDED that no Bank other than Fleet shall be required to be a
Fronting Bank.

    Section 3.2.   REIMBURSEMENT OBLIGATION OF THE BORROWER. In order to induce
the Fronting Bank to issue, extend and renew each Letter of Credit and the Banks
to participate therein, the Borrower hereby agrees, except as contemplated in
Section 3.3, to reimburse or pay to the Fronting Bank, for the account of the
Fronting Bank or (as the case may be) the Banks, with respect to each Letter of
Credit issued, extended or renewed by the Fronting Bank hereunder,

                   (a) except as otherwise expressly provided in Section 3.2(b)
and (c) or Section 3.3, promptly upon notification by the Fronting Bank or the
Agent that any draft presented

                                      -47-
<Page>

under such Letter of Credit is honored by the Fronting Bank, or the Fronting
Bank otherwise makes a payment with respect thereto, (i) the amount paid by the
Fronting Bank under or with respect to such Letter of Credit, and (ii) any
amounts payable pursuant to Section 5.5 under, or with respect to, such Letter
of Credit,

                   (b) upon the reduction (but not termination) of the Total
Commitment to an amount less than the then Maximum Drawing Amount (after taking
into account all outstanding Loans and Reimbursement Obligations, if any
(without double counting)), an amount equal to such difference, which amount
shall be held by the Agent in an interest-bearing account (with interest to be
added to such account) as cash collateral for the benefit of the Banks and the
Agent for all Reimbursement Obligations, and

                   (c) upon the termination of the Total Commitment, or the
acceleration of the Reimbursement Obligations with respect to all Letters of
Credit in accordance with Section 14, an amount equal to the then Maximum
Drawing Amount on all Letters of Credit, which amount shall be held by the Agent
in an interest-bearing account (with interest to be added to such account) as
cash collateral for the benefit of the Banks and the Agent for all Reimbursement
Obligations.

    Each such payment shall be made to the Agent for the benefit of the Banks at
the Agent's Head Office in immediately available funds. Interest on any and all
amounts not converted to a Revolving Credit Loan pursuant to Section 3.3 and
remaining unpaid by the Borrower under this Section 3.2 at any time from the
date such amounts become due and payable (whether as stated in this Section 3.2,
by acceleration or otherwise) until payment in full (whether before or after
judgment) shall be payable to the Agent for the benefit of the Banks on demand
at the rate specified in Section 5.9 for overdue principal on the Loans.

    Section 3.3.   LETTER OF CREDIT PAYMENTS; FUNDING OF A LOAN. If any draft
shall be presented or other demand for payment shall be made under any Letter of
Credit, the Fronting Bank will use its best efforts to notify the Borrower and
the Banks, on or before the date the Fronting Bank intends to honor such
drawing, of the date and amount of the draft presented or demand for payment and
of the date and time when it expects to pay such draft or honor such demand for
payment and, except to the extent the amount of such draft becomes a Revolving
Credit Loan as set forth in this Section 3.3, Borrower shall reimburse Agent, as
set forth in Section 3.2. Notwithstanding anything contained in Section 3.2 or
this Section 3.3 to the contrary, however, unless Borrower shall have notified
the Agent and Fronting Bank prior to 11:00 a.m. (New York time) on the Business
Day immediately prior to the date of such drawing that Borrower intends to
reimburse Fronting Bank for the amount of such drawing with funds other than the
proceeds of Revolving Credit Loans, Borrower shall be deemed to have timely
given a Completed Loan Request pursuant to Section 2.4 to Agent, requesting a
Prime Rate Loan on the date on which such drawing is honored and in an amount
equal to the amount of such drawing. The Borrower may thereafter convert any
such Prime Rate Loan to a Revolving Credit Loan of another Type in accordance
with Section 2.5. Each Bank shall, in accordance with Section 2.6, make
available such Bank's

                                      -48-
<Page>

Commitment Percentage of such Revolving Credit Loan to Agent, the proceeds of
which shall be applied directly by Agent to reimburse Fronting Bank for the
amount of such draw. In the event that any Bank fails to make available to Agent
the amount of such Bank's Commitment Percentage of such Revolving Credit Loan on
the date of any drawing, Agent shall be entitled to recover such amount on
demand from such Bank plus any additional amounts payable under Section 2.6(b)
in the event of a late funding by a Bank. The Fronting Bank is irrevocably
authorized by the Borrower and each of the Banks to honor draws on each Letter
of Credit by the beneficiary thereof in accordance with the terms of such Letter
of Credit. The responsibility of the Agent to the Borrower and the Banks shall
be only to determine that the documents (including each draft) delivered under
each Letter of Credit in connection with such presentment shall be in conformity
in all material respects with such Letter of Credit.

    Section 3.4.   OBLIGATIONS ABSOLUTE. The Borrower's obligations under this
Section 3 shall be absolute and unconditional under any and all circumstances
and irrespective of the occurrence of any Default or Event of Default or any
condition precedent whatsoever or any setoff, counterclaim or defense to payment
which the Borrower may have or have had against the Agent, any Bank or any
beneficiary of a Letter of Credit. The Borrower further agrees with the Agent
and the Banks that the Agent and the Banks shall not be responsible for, and the
Borrower's Reimbursement Obligations under Section 3.2 shall not be affected by,
among other things, the validity or genuineness of documents or of any
endorsements thereon (so long as the documents delivered under each Letter of
Credit in connection with such presentment shall be in the form required by, and
in conformity in all material respects with, such Letter of Credit), even if
such documents should in fact prove to be in any or all respects invalid,
fraudulent or forged, or any dispute between or among the Borrower, the
beneficiary of any Letter of Credit or any financing institution or other party
to whom any Letter of Credit may be transferred, or any claims or defenses
whatsoever of the Borrower against the beneficiary of any Letter of Credit or
any such transferee. The Agent and the Banks shall not be liable for any error,
omission, interruption or delay in transmission, dispatch or delivery of any
message or advice, however transmitted, in connection with any Letter of Credit.
The Borrower agrees that any action taken or omitted by the Agent or any Bank
under or in connection with each Letter of Credit and the related drafts and
documents, if done in good faith and absent gross negligence, shall be binding
upon the Borrower and shall not result in any liability on the part of the Agent
or any Bank to the Borrower.

    Section 3.5.   RELIANCE BY ISSUER. To the extent not inconsistent with
Section 3.4, the Agent and any Fronting Bank shall be entitled to rely, and
shall be fully protected in relying upon, any Letter of Credit, draft, writing,
resolution, notice, consent, certificate, affidavit, letter, cablegram,
telegram, telecopy, telex or teletype message, statement, order or other
document believed by it to be genuine and correct and to have been signed, sent
or made by the proper Person or Persons and upon advice and statements of legal
counsel, independent accountants and other experts selected by the Agent. The
Agent and any Fronting Bank shall be fully justified in failing or refusing to
take any action under this Section 3

                                      -49-
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(other than the issuance of a Letter of Credit pursuant to a Letter of Credit
Application and otherwise in accordance with the terms of this Agreement) unless
it shall first have received such advice or concurrence of the Majority Banks
(or such other number or percentage of the Banks as may be required by this
Agreement) as it reasonably deems appropriate or it shall first be indemnified
to its reasonable satisfaction by the Banks against any and all liability and
expense which may be incurred by it by reason of taking or continuing to take
any such action. The Agent and any Fronting Bank shall in all cases be fully
protected by the Banks in acting, or in refraining from acting, under this
Section 3 in accordance with a request of the Majority Banks(or such other
number or percentage of the Banks as may be required by this Agreement), and
such request and any action taken or failure to act pursuant thereto shall be
binding upon the Banks and all future holders of the Notes or of a Letter of
Credit Participation.

    Section 3.6.   LETTER OF CREDIT FEE. The Borrower shall pay to the Agent a
fee (in each case, a "Letter of Credit Fee") in an amount equal to the
Applicable L/C Percentage of the undrawn amount of each outstanding Letter of
Credit, which fee (a) shall be payable quarterly in arrears on the first day of
each calendar quarter for the immediately preceding calendar quarter, with a
final payment on the Maturity Date or any earlier date on which the Commitments
shall terminate (which Letter of Credit Fee shall be pro-rated for any calendar
quarter in which such Letter of Credit is issued, drawn upon or otherwise
reduced or terminated) and (b) shall be for the accounts of the Banks as
follows: (i) an amount equal to 0.125% per annum of the Letter of Credit Fee
shall be for the account of the Fronting Bank and (ii) the remainder of the
Letter of Credit Fee shall be for the accounts of the Banks (including the
Fronting Bank) PRO RATA in accordance with their respective Commitment
Percentages.

    Section 4.     REPAYMENT OF THE LOANS.

    Section 4.1.   MATURITY. In addition to, and without limiting, the
provisions of Section 2.8(b) and Section 2.9(f), the Borrower promises to pay on
the Maturity Date, and there shall become absolutely due and payable on the
Maturity Date, all unpaid principal of the Revolving Credit Loans and each other
Loan, if any, outstanding on such date, together with any and all accrued and
unpaid interest thereon, the unpaid balance of the Facility Fee accrued through
such date, and any and all other unpaid amounts due under this Agreement, the
Notes or any other of the Loan Documents.

    Section 4.2.   OPTIONAL REPAYMENTS OF REVOLVING CREDIT LOANS. The Borrower
shall have the right, at its election, to prepay the outstanding amount of the
Revolving Credit Loans, in whole or in part, at any time without penalty or
premium; PROVIDED that the outstanding amount of any Eurodollar Rate Loans may
not be prepaid unless the Borrower pays the Eurodollar Breakage Costs for each
Eurodollar Rate Loan so prepaid at the time of such prepayment. The Borrower
shall give the Agent (with copies to the Agent for each Bank), no later than
10:00 a.m., Boston, Massachusetts time, at least two (2) Business Days' prior
written notice of any prepayment pursuant to this Section 4.2 of any

                                      -50-
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Prime Rate Loans, and at least four (4) Eurodollar Business Days' notice of any
proposed prepayment pursuant to this Section 4.2 of Eurodollar Rate Loans,
specifying the proposed date of prepayment of Revolving Credit Loans and the
principal amount to be prepaid. Each such partial prepayment of the Loans shall
be in an amount equal to $500,000 or an integral multiple of $100,000 in excess
thereof or, if less, the outstanding balance of the Revolving Credit Loans then
being repaid, shall be accompanied by the payment of all charges, if any,
outstanding on all Revolving Credit Loans so prepaid and of all accrued interest
on the principal prepaid to the date of payment, and shall be applied, in the
absence of instruction by the Borrower, first to the principal of Prime Rate
Loans and then to the principal of Eurodollar Rate Loans.

    Section 4.3    MANDATORY REPAYMENT OF LOANS. If at any time the sum of the
outstanding amount of the Loans, PLUS the Maximum Drawing Amount, PLUS without
double-counting any Revolving Credit Loans, the outstanding Reimbursement
Obligations, if any, exceeds the lesser of (i) the Total Commitment at such
time, or (ii) the Borrowing Base Availability at such time, the Borrower shall,
within fifteen (15) days after receiving notice of such excess from the Agent
(i) pay to the Agent an amount in cash necessary to eliminate such excess, such
amount to be applied, in the absence of instruction by the Borrower, (x) first
to the repayment of Swingline Loans, second to the repayment of Revolving Credit
Loans and third to the repayment of Bid Rate Loans and (y) with respect to any
such payments of Revolving Credit Loans, first to the principal of Prime Rate
Loans and then to the principal of Eurodollar Rate Loans, or (ii) add one (1) or
more Real Estate Assets to the Borrowing Base which have Borrowing Base Values,
in the aggregate, sufficient to eliminate such excess.

    Section 5.     CERTAIN GENERAL PROVISIONS.

    Section 5.1.   FUNDS FOR PAYMENTS.

                   (a) All payments of principal, interest, fees, and any other
amounts due hereunder or under any of the other Loan Documents shall be made to
the Agent, for the respective accounts of the Banks or (as the case may be) the
Agent, at the Agent's Head Office, in each case in Dollars and in immediately
available funds. The Borrower shall make each payment of principal of and
interest on the Loans and of fees hereunder and Reimbursement Obligations which
are not converted to a Loan hereunder not later than 1:00 p.m. (Boston,
Massachusetts time) on the due date thereof.

                   (b) All payments by the Borrower hereunder and under any of
the other Loan Documents shall be made without setoff or counterclaim and free
and clear of and without deduction for any taxes, levies, imposts, duties,
charges, fees, deductions, withholdings, compulsory liens, restrictions or
conditions of any nature now or hereafter imposed or levied by any jurisdiction
or any political subdivision thereof or taxing or other authority therein unless
the Borrower is compelled by law to make such deduction or withholding. If the
Borrower is compelled by law to make any such deduction or

                                      -51-
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withholding with respect to any amount payable by it hereunder or under any of
the other Loan Documents (except with respect to taxes on the income or profits
of the Agent or any Bank), the Borrower shall pay to the Agent, for the account
of the Banks or (as the case may be) the Agent, on the date on which such amount
is due and payable hereunder or under such other Loan Document, such additional
amount in Dollars as shall be necessary to enable the Banks to receive the same
net amount which the Banks would have received on such due date had no such
obligation been imposed upon the Borrower. The Borrower will deliver promptly to
the Agent (with copies to the Agent for each Bank) certificates or other valid
vouchers for all taxes or other charges deducted from or paid with respect to
payments made by the Borrower hereunder or under such other Loan Document.

    Section 5.2.   COMPUTATIONS. All computations of interest on the Loans and
of other fees to the extent applicable shall be based on a 360-day year and paid
for the actual number of days elapsed. Except as otherwise provided in the
definition of the term "Interest Period" with respect to Eurodollar Rate Loans,
whenever a payment hereunder or under any of the other Loan Documents becomes
due on a day that is not a Business Day, the due date for such payment shall be
extended to the next succeeding Business Day, and interest shall accrue during
such extension. The outstanding amount of the Loans as reflected on the Note
Records or record attached to any other Note from time to time shall constitute
prima facie evidence of the principal amount thereof.

    Section 5.3.   INABILITY TO DETERMINE EURODOLLAR RATE. In the event, prior
to the commencement of any Interest Period relating to any Eurodollar Rate Loan,
the Agent shall reasonably and in good faith determine that adequate and
reasonable methods do not exist for ascertaining the Eurodollar Rate that would
otherwise determine the rate of interest to be applicable to any Eurodollar Rate
Loan during any Interest Period, the Agent shall forthwith give notice of such
determination (which shall be conclusive and binding on the Borrower) to the
Borrower and the Banks. In such event (a) any Loan Request with respect to
Eurodollar Rate Loans shall be automatically withdrawn and shall be deemed a
request for Prime Rate Loans, (b) each Eurodollar Rate Loan will automatically,
on the last day of the then current Interest Period applicable thereto, become a
Prime Rate Loan, and (c) the obligations of the Banks to make Eurodollar Rate
Loans shall be suspended, in each case unless and until the Agent reasonably and
in good faith determines that the circumstances giving rise to such suspension
no longer exist, whereupon the Agent shall so notify the Borrower and the Banks.

    Section 5.4.   ILLEGALITY. Notwithstanding any other provisions herein, if
any present or future law, regulation, treaty or directive or in the
interpretation or application thereof shall make it unlawful for any Bank to
make or maintain Eurodollar Rate Loans, such Bank shall forthwith give notice of
such circumstances to the Borrower and thereupon (a) the Commitment of such Bank
to make Eurodollar Rate Loans or convert Prime Rate Loans to Eurodollar Rate
Loans shall forthwith be suspended and (b) such Bank's Commitment Percentage of
Eurodollar Rate Loans then outstanding shall be converted

                                      -52-
<Page>

automatically to Prime Rate Loans on the last day of each Interest Period
applicable to such Eurodollar Rate Loans or within such earlier period as may be
required by law, all until such time as it is no longer unlawful for such Bank
to make or maintain Eurodollar Rate Loans. Subject to the limitations set forth
in Section 5.7, the Borrower hereby agrees promptly to pay the Agent for the
account of such Bank, upon demand, any additional amounts necessary to
compensate such Bank for any costs incurred by such Bank in making any
conversion required by this Section 5.4 prior to the last day of an Interest
Period with respect to a Eurodollar Rate Loan, including any interest or fees
payable by such Bank to lenders of funds obtained by it in order to make or
maintain its Eurodollar Rate Loans hereunder.

    Section 5.5.   ADDITIONAL COSTS, ETC. If any present or future applicable
law, which expression, as used herein, includes statutes, rules and regulations
thereunder and interpretations thereof by any competent court or by any
governmental or other regulatory body or official charged with the
administration or the interpretation thereof and requests, directives,
instructions and notices at any time or from time to time hereafter made upon or
otherwise issued to any Bank or the Agent by any central bank or other fiscal,
monetary or other authority (whether or not having the force of law, but if not
having the force of law, then generally applied by the Banks or the Agent with
respect to similar loans), shall:

                   (a) subject any Bank or the Agent to any tax, levy, impost,
duty, charge, fee, deduction or withholding of any nature with respect to this
Agreement, the other Loan Documents, any Letters of Credit, such Bank's
Commitment or the Loans (other than taxes based upon or measured by the income
or profits of such Bank or the Agent), or

                   (b) materially change the basis of taxation (except for
changes in taxes on income or profits) of payments to any Bank of the principal
of or the interest on any Loans or any other amounts payable to the Agent or any
Bank under this Agreement or the other Loan Documents, or

                   (c) impose or increase or render applicable (other than to
the extent specifically provided for elsewhere in this Agreement) any special
deposit, reserve, assessment, liquidity, capital adequacy or other similar
requirements (whether or not having the force of law) against assets held by, or
deposits in or for the account of, or loans by, or letters of credit issued by,
or commitments of an office of any Bank, or

                   (d) impose on any Bank or the Agent any other conditions or
requirements with respect to this Agreement, the other Loan Documents, any
Letters of Credit, the Loans, such Bank's Commitment, or any class of loans,
letters of credit or commitments of which any of the Loans or such Bank's
Commitment forms a part;

and the result of any of the foregoing is

                                      -53-
<Page>

                       (i)   to increase the cost to any Bank of making,
                   funding, issuing, renewing, extending or maintaining any of
                   the Loans or such Bank's Commitment or any Letter of Credit,
                   or

                       (ii)  to reduce the amount of principal, interest,
                   Reimbursement Obligation or other amount payable to such Bank
                   or the Agent hereunder on account of such Bank's Commitment,
                   any Letter of Credit or any of the Loans, or

                       (iii) to require such Bank or the Agent to make any
                   payment or to forego any interest or Reimbursement Obligation
                   or other sum payable hereunder, the amount of which payment
                   or foregone interest or Reimbursement Obligation or other sum
                   is calculated by reference to the gross amount of any sum
                   receivable or deemed received by such Bank or the Agent from
                   the Borrower hereunder,

then, and in each such case, the Borrower will, within thirty (30) days after
notice by the Agent or such Bank (such notice to be given promptly by the Agent
or such Bank upon the making of any such determination), at any time and from
time to time and as often as the occasion therefor may arise, but subject to the
limitations set forth in Section 5.7, pay to such Bank or the Agent such
additional amounts as such Bank or the Agent shall determine in good faith to be
sufficient to compensate such Bank or the Agent for such additional cost,
reduction, payment or foregone interest or other sum, PROVIDED that such Bank or
the Agent is generally imposing similar charges on its other similarly situated
borrowers.

    Section 5.6.   CAPITAL ADEQUACY. If any future law, governmental rule,
regulation, policy, guideline or directive (whether or not having the force of
law, but if not having the force of law, then generally applied by the Banks
with respect to similar loans) or the interpretation thereof by a court or
governmental authority with appropriate jurisdiction affects the amount of
capital required or expected to be maintained by banks or bank holding companies
and any Bank or the Agent determines that the amount of capital required to be
maintained by it is increased by or based upon the existence of Loans made or
deemed to be made pursuant hereto, then such Bank or the Agent may notify the
Borrower of such fact, and the Borrower shall pay to such Bank or the Agent from
time to time, within thirty (30) days after notice by the Agent or such Bank
(such notice to be given promptly by the Agent or such Bank upon the making of
any such determination), as an additional fee payable hereunder, but subject to
the limitations set forth in Section 5.7, such amount as such Bank or the Agent
shall determine reasonably and in good faith and certify in a notice to the
Borrower to. be an amount that will adequately compensate such Bank in light of
these circumstances for its increased costs of maintaining such capital. Each
Bank and the Agent shall allocate such cost increases among its customers in
good faith and on an equitable basis, and will not charge the Borrower unless it
is generally imposing a similar charge on its other similarly situated
borrowers.

                                      -54-
<Page>

    Section 5.7.   CERTIFICATE; LIMITATIONS. A certificate setting forth any
additional amounts payable pursuant to Section Section 5.5 or 5.6 and a brief
explanation of such amounts which are due, including reasonably detailed
information regarding the method and calculation of such amount, submitted by
any Bank or the Agent to the Borrower, shall be PRIMA FACIE evidence that such
amounts are due and owing. Notwithstanding anything to the contrary contained in
this Article 5, (i) to the extent reasonably possible, each Bank shall designate
an alternate lending office in the continental United States to make the Loans
in order to reduce any liability of Borrower to such Bank under Section Section
5.4, 5.5 or 5.6 or to avoid the unavailability of a Eurodollar Rate Loan, so
long as such designation is not disadvantageous to such Bank, and (ii) the
Borrower shall not be obligated to compensate any Bank pursuant to Section
Section 5.4, 5.5 or 5.6 for any amounts attributable to any period which is more
than one (1) year prior to the date of delivery of the certificate set forth in
the first sentence of this Section 5.7.

    Section 5.8.   INDEMNITY. In addition to the other provisions of this
Agreement regarding such matters, the Borrower agrees to indemnify the Agent and
each Bank and to hold the Agent and each Bank harmless from and against any
loss, cost or expense (including loss of the spread to which such Bank would
have been entitled through the end of the applicable Interest Period in excess
of the applicable interest rate(s) then in effect) that the Agent or such Bank
may sustain or incur as a consequence of (a) a default by the Borrower in the
payment of any principal amount of or any interest on any Eurodollar Rate Loans
as and when due and payable, including any such loss or expense arising from
interest or fees payable by the Agent or such Bank to lenders of funds obtained
by it in order to maintain its Eurodollar Rate Loans, (b) the failure by the
Borrower to make a borrowing or conversion after the Borrower has given a
Completed Loan Request for a Eurodollar Rate Loan or a Conversion Request for a
Eurodollar Rate Loan, and (c) the making of any payment of a Eurodollar Rate
Loan or the making of any conversion of any such Loan to a Prime Rate Loan on a
day that is not the last day of the applicable Interest Period with respect
thereto, including interest or fees payable by the Agent or a Bank to lenders of
funds obtained by it in order to maintain any such Eurodollar Rate Loans;
PROVIDED, HOWEVER, that the Borrower shall not be required to so indemnify any
Bank pursuant to clause (b) above during and for any period of time when such
Bank has wrongfully failed or refused to fund its proportionate share of a Loan
in accordance with the terms of this Agreement and is a Delinquent Bank.

    Section 5.9.   INTEREST ON OVERDUE AMOUNTS. Overdue principal and (to the
extent permitted by applicable law) interest on the Loans and all other overdue
amounts payable hereunder or under any of the other Loan Documents shall bear
interest payable on demand at a rate per annum equal to three percent (3%) PLUS
the Prime Rate until such amount shall be paid in full (after as well as before
judgment). In addition, the Borrower shall pay a late charge equal to three
percent (3%) of any amount of interest charges on the Loans which is not paid
within ten (10) days of the date when due.

                                      -55-
<Page>

    Section 6.     RECOURSE OBLIGATIONS. The Obligations are full recourse
obligations of the Borrower, and all of the respective assets and properties of
the Borrower shall be available for the payment in full in cash and performance
of the Obligations. In no event shall BPI have any personal liability hereunder
or under any of the other Loan Documents, either individually or as general
partner of BPLP or any other Borrower, by application of applicable law or
otherwise, except to the extent BPI misappropriates funds, rents or insurance
proceeds or engages in gross negligence, willful misconduct or fraud.

    Section 7.     REPRESENTATIONS AND WARRANTIES. The Borrower for itself and
for BPI insofar as any such statements relate to BPI represents and warrants to
the Banks all of the statements contained in this Section 7.

    Section 7.1.   AUTHORITY, ETC.

                   (a) ORGANIZATION: GOOD STANDING.

                            (i)  The Borrower is a limited partnership, general
                       partnership, nominee trust or limited liability company,
                       as the case may be, duly organized, validly existing and
                       in good standing under the laws of its state of
                       organization, unless the failure to be so does not relate
                       to BPLP or BPI and is a Non-Material Breach; the Borrower
                       has all requisite limited partnership, general
                       partnership, trust, limited liability company or
                       corporate, as the case may be, power to own its
                       respective properties and conduct its respective business
                       as now conducted and as presently contemplated, unless
                       any such failure to have any of the foregoing does not
                       relate to BPLP or BPI and is a Non-Material Breach; and
                       the Borrower is in good standing as a foreign entity and
                       is duly authorized to do business in the jurisdictions
                       where the Borrowing Base Properties owned or
                       ground-leased by it are located and in each other
                       jurisdiction where such qualification is necessary except
                       where a failure to be so qualified in such other
                       jurisdiction would not have a materially adverse effect
                       on any of their respective businesses, assets or
                       financial conditions.

                            (ii) BPI is a corporation duly organized, validly
                       existing and in good standing under the laws of the State
                       of Delaware; each Subsidiary of BPI is duly organized,
                       validly existing and in good standing as a corporation,
                       nominee trust, limited liability company, limited
                       partnership or general partnership, as the case may be,
                       under the laws of the state of its organization, unless
                       the failure to be so does not relate to BPLP and is a
                       Non-Material Breach; BPI and each of its Subsidiaries has
                       all requisite corporate, trust,

                                      -56-
<Page>

                       limited liability company, limited partnership or general
                       partnership, as the case may be, power to own its
                       respective properties and conduct its respective business
                       as now conducted and as presently contemplated, unless
                       any such failure to have any of the foregoing does not
                       relate to BPLP or BPI and is a Non-Material Breach; and
                       BPI is in good standing as a foreign entity and is duly
                       authorized to do business in the jurisdictions where such
                       qualification is necessary (including in the Commonwealth
                       of Massachusetts) except where a failure to be so
                       qualified in such other would not have a materially
                       adverse effect on the business, assets or financial
                       condition of BPI.

                   (b) CAPITALIZATION. The outstanding equity of BPLP is
comprised of a general partner interest and limited partner interests, all of
which have been duly issued and are outstanding and fully paid and
non-assessable. All of the issued and outstanding general partner interests of
the BPLP are owned and held of record by BPI. There are no outstanding
securities or agreements exchangeable for or convertible into or carrying any
rights to acquire a general partner interest in BPLP. There are no outstanding
commitments, options, warrants, calls or other agreements (whether written or
oral) binding on BPLP or BPI which require or could require BPLP or BPI to sell,
grant, transfer, assign, mortgage, pledge or otherwise dispose of any general
partner interest in BPLP. Except as set forth in the Agreement of Limited
Partnership of BPLP, no general partner interests of BPLP are subject to any
restrictions on transfer or any partner agreements, voting agreements, trust
deeds, irrevocable proxies; or any other similar agreements or interests
(whether written or oral). For so long as any Borrower which is a Wholly-owned
Subsidiary is a Borrower, BPLP owns, directly or indirectly, at least a majority
(by number of votes or controlling interests) of the outstanding voting
interests and at least 99% of the economic interests in each of the Borrowers
other than BPLP. All of the Preferred Creditor Equity which exists as of the
date of this Agreement, and each of the agreements or other documents entered
into and/or setting forth the terms, rights and restrictions applicable to any
such Preferred Creditor Equity, are listed and described on SCHEDULE 7.1(B)
attached hereto. All of the agreements and other documents relating to the
Preferred Equity in effect on the Closing Date have been furnished to the Agent.

                   (c) DUE AUTHORIZATION. The execution, delivery and
performance of this Agreement and the other Loan Documents to which the Borrower
or BPI is or is to become a party and the transactions contemplated hereby and
thereby (i) are within the authority of the Borrower and BPI, (ii) have been
duly authorized by all necessary proceedings on the part of the Borrower or BPI
and any general partner thereof, (iii) do not materially conflict with or result
in any breach or contravention of any provision of law, statute, rule or
regulation to which the Borrower or BPI is subject or any judgment, order, writ,
injunction, license or permit applicable to the Borrower or BPI, unless any such
conflict, breach or contravention does not relate to BPLP or BPI and is a
Non-Material Breach, (iv) do not conflict with any provision of the agreement of
limited

                                      -57-
<Page>

partnership, any certificate of limited partnership, the charter documents or
by-laws of the Borrower or BPI or any general partner thereof, and (v) do not
contravene any provisions of, or constitute Default or Event of Default
hereunder or a failure to comply with any term, condition or provision of, any
other agreement, instrument, judgment, order, decree, permit, license or
undertaking binding upon or applicable to the Borrower or BPI or any of the
Borrower's or BPI's properties (except for any such failure to comply under any
such other agreement, instrument, judgment, order, decree, permit, license, or
undertaking as would not materially and adversely affect the condition
(financial or otherwise), properties, business or results of operations of BPLP,
BPI or, taken as a whole, the BP Group) or result in the creation of any
mortgage, pledge, security interest, lien, encumbrance or charge upon any of the
properties or assets of the Borrower or BPI.

                   (d) ENFORCEABILITY. Each of the Loan Documents to which the
Borrower or BPI is a party has been duly executed and delivered and constitutes
the legal, valid and binding obligations of the Borrower and BPI, as the case
may be, subject only to applicable bankruptcy, insolvency, reorganization,
moratorium or other laws relating to or affecting generally the enforcement of
creditors' rights and to the fact that the availability of the remedy of
specific performance or injunctive relief is subject to the discretion of the
court before which any proceeding therefor may be brought.

    Section 7.2.   GOVERNMENTAL APPROVALS. The execution, delivery and
performance by the Borrower of this Agreement and by the Borrower and BPI of the
other Loan Documents to which the Borrower or BPI is or is to become a party and
the transactions contemplated hereby and thereby do not require (i) the approval
or consent of any governmental agency or authority other than those already
obtained or those which would not have a material adverse effect on BPLP, BPI
or, taken as a whole, the BP Group, or (ii) filing with any governmental agency
or authority, other than filings which will be made with the SEC when and as
required by law or deemed appropriate by BPI.

    Section 7.3.   TITLE TO PROPERTIES; LEASES.

    The Borrower and BPI each has good fee or leasehold title to all of its
respective properties, assets and rights of every name and nature purported to
be owned by it, including, without limitation, that:

                   (a) As of the Closing Date (with respect to Borrowing Base
Properties designated as such on the Closing Date) or the date of designation as
a Borrowing Base Properties (with respect to Borrowing Base Properties acquired
and/or designated as such after the Closing Date), and in each case to the best
of its knowledge thereafter (but only for so long as such Real Estate Assets
continue to be Borrowing Base Properties), the Borrower holds good and clear
record and marketable fee simple or leasehold title to (or an undivided
condominium interest in) the Borrowing Base Properties, subject to no Liens,
except for Permitted Liens and, in the case of any ground-leased Borrowing Base
Property, the terms of such ground lease, as the same may then or thereafter be
amended

                                      -58-
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from time to time in a manner consistent with the minimum term for ground leases
set forth in the definition of "Real Estate Assets" in Section 1.1 above.

                   (b) The Borrower and BPI will, as of the Closing Date, own
all of the assets as reflected in the financial statements of the Borrower and
BPI described in Section 7.4, the Registration Statement, the Prospectus, the
preliminary Prospectus and any so-called follow-on prospectus or acquired since
the date of such financial statements (except property and assets sold or
otherwise disposed of in the ordinary course of business since that date).

    Section 7.4.   FINANCIAL STATEMENTS. The following financial statements have
been furnished to each of the Banks:

                   The consolidated balance sheet of BPI and its Subsidiaries as
of December 31, 2001 (together with the unaudited consolidated balance sheet of
BPI and its Subsidiaries as of September 30, 2002), and their related
consolidated statements of income, changes in shareholders' equity and cash
flows for the fiscal year or other period then ended, as applicable, and setting
forth in comparative form the figures as of the end of and for the previous
fiscal year or other period, as applicable, prepared in accordance with GAAP
and, with respect to the December 31, 2001 statements, accompanied by an
auditor's report prepared without qualification by the Accountants
(collectively, the "Initial Financial Statements"). The Initial Financial
Statements fairly present the financial condition of BPI and its Subsidiaries as
at the close of business on the date thereof and the results of operations for
the fiscal year or other period then ended, as applicable. There are no
contingent liabilities of BPI or any of its Subsidiaries as of such date
involving material amounts, known to the officers of BPI or any of its
Subsidiaries not disclosed in said Initial Financial Statements.

    Section 7.5    NO MATERIAL CHANGES, ETC. Since the Financial Statement Date,
there has occurred no materially adverse change in the financial condition or
business of BPLP, BPI or, taken as a whole, the BP Group, other than changes in
the ordinary course of business that have not had any materially adverse effect
either individually or in the aggregate on the business or financial condition
of BPLP, BPI or, taken as a whole, the BP Group. Between the Financial Statement
Date and the Closing Date, there has been no material adverse change to the Net
Operating Income of any Real Estate Asset that is a Borrowing Base property on
the Closing Date.

    Section 7.6.   FRANCHISES, PATENTS, COPYRIGHTS, ETC. Except to the extent
the failure or breach of such representation or warranty constitutes a
Non-Material Breach, the Borrower, BPI and each of their respective Subsidiaries
possess all franchises, patents, copyrights, trademarks, trade names, licenses
and permits, and rights in respect of the foregoing, adequate for the conduct of
their respective businesses substantially as now conducted without known
conflict with any rights of others, including all material Permits.

                                      -59-
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    Section 7.7    LITIGATION. Except as stated on SCHEDULE 7.7, there are no
actions, suits, proceedings or investigations of any kind pending or, to the
Borrower's knowledge, threatened against the Borrower, BPI or any of their
respective Subsidiaries before any court, tribunal or administrative agency or
board that, if adversely determined, might, either individually or in the
aggregate, materially adversely affect the properties, assets, financial
condition or business of BPLP, BPI or, taken as a whole, the BP Group, or
materially impair the right of BPLP, BPI or, taken as a whole, the BP Group, to
carry on their respective businesses substantially as now conducted by them, or
result in any substantial liability not adequately covered by insurance, or for
which adequate reserves are not maintained, as reflected in the applicable
consolidated financial statements or SEC Filings of the Borrower and BPI, or
which question the validity of this Agreement or any of the other Loan
Documents, or any action taken or to be taken pursuant hereto or thereto.

    Section 7.8.   NO MATERIALLY ADVERSE CONTRACTS, ETC. Neither the Borrower,
BPI nor any of their respective Subsidiaries is subject to any charter,
corporate, partnership or other legal restriction, or any judgment, decree,
order, rule or regulation that has or is reasonably expected in the future to
have (and with respect solely to any restriction on the timing of any sale or
refinancing of a Real Estate Asset which would be an acceptable Lien under the
definition of "Unencumbered Asset" contained in an Organizational Document, such
expectation existed at the time such restriction was imposed) a materially
adverse effect on the respective businesses, assets or financial conditions of
BPLP, BPI or, taken as a whole, the BP Group. None of the Borrower, BPI or any
of their respective Subsidiaries is a party to any contract or agreement that
has or is expected, in the judgment of their respective officers, to have any
materially adverse effect on the respective businesses of the BPLP, BPI or,
taken as a whole, the BP Group.

    Section 7.9.   COMPLIANCE WITH OTHER INSTRUMENTS, LAWS, ETC. Neither the
Borrower, BPI nor any of their respective Subsidiaries is in violation of any
provision of its partnership agreement or charter, as the case may be, or any
respective agreement or instrument to which it may be subject or by which it or
any of its properties may be bound or any decree, order, judgment, statute,
license, rule or regulation, in any of the foregoing cases in a manner that
could result, individually or in the aggregate, in the imposition of substantial
penalties or materially and adversely affect the financial condition, properties
or businesses of the BPLP, BPI or, taken as a whole, the BP Group.

    Section 7.10.  TAX STATUS. (i) Each of the Borrower, BPI and their
respective Subsidiaries (a) has made or filed all federal, state and local
income and all other tax returns, reports and declarations required by any
jurisdiction to which it is subject, (b) has paid all taxes and other
governmental assessments and charges shown or determined to be due on such
returns, reports and declarations, except those being contested in good faith
and by appropriate proceedings, and (c) has set aside on its books provisions
reasonably adequate for the payment of all taxes for periods subsequent to the
periods to which such

                                      -60-
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returns, reports or declarations apply, and (ii) there are no unpaid taxes in
any material amount claimed to be due by the taxing authority of any
jurisdiction, and the respective officers of the Borrower and BPI and their
respective Subsidiaries know of no basis for any such claim.

    Section 7.11   NO EVENT OF DEFAULT. No Default or Event of Default has
occurred and is continuing.

    Section 7.12.  INVESTMENT COMPANY ACTS. None of the Borrower, BPI or any of
their respective Subsidiaries is an "investment company", or an "affiliated
company" or a "principal underwriter" of an "investment company", as such terms
are defined in the Investment Company Act of 1940.

    Section 7.13.  ABSENCE OF UCC FINANCING STATEMENTS, ETC. Except for
Permitted Liens and except to the extent the failure or breach of such
representation and warranty constitutes a Non-Material Breach, there is no
financing statement, security agreement, chattel mortgage, real estate mortgage,
equipment lease, financing lease, option, encumbrance or other document filed or
recorded with any filing records, registry, or other public office, that
purports to cover, affect or give notice of any present or possible future lien
or encumbrance on, or security interest in, any Borrowing Base Property. Neither
the Borrower nor BPI has pledged or granted any lien on or security interest in
or otherwise encumbered or transferred any of their respective interests in any
Subsidiary who is a Borrower (including in the case of BPI, its interests in
BPLP), unless such pledge, lien or security interest relates only to a Borrower
other than BPLP and is a Non-Material Breach.

    Section 7.14.  ABSENCE OF LIENS. The Borrower is the owner of or the holder
of a ground leasehold interest in the Borrowing Base Properties free from any
Lien, except for Permitted Liens.

    Section 7.15.  CERTAIN TRANSACTIONS. [Intentionally Omitted.]

    Section 7.16.  EMPLOYEE BENEFIT PLANS; MULTIEMPLOYER PLANS; GUARANTEED
PENSION PLANS. Except as disclosed in the SEC Filings or on SCHEDULE 7.16, none
of the Borrower, BPI nor any ERISA Affiliate maintains or contributes to any
Employee Benefit Plan, Multiemployer Plan or Guaranteed Pension Plan.

    Section 7.17.  REGULATIONS U AND X. No portion of any Loan is to be used,
and no portion of any Letter of Credit is to be obtained, for the purpose of
purchasing or carrying any "margin security" or "margin stock" as such terms are
used in Regulations U and X of the Board of Governors of the Federal Reserve
System, 12 C.F.R. Parts 221 and 224.

    Section 7.18.  ENVIRONMENTAL COMPLIANCE. The Borrower has caused Phase I and
other environmental assessments (collectively, the "Environmental Reports") to
be conducted

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and/or taken other steps to investigate the past and present environmental
condition and usage of the Real Estate Assets. Based upon such Environmental
Reports, to the Borrower's knowledge, except as identified in such Environmental
Reports, the Borrower makes the following representations and warranties:

                   (a) None of the Borrower, its Subsidiaries, BPI or any
operator of the Real Estate Assets or any portion thereof, or any operations
thereon is in material violation, or alleged material violation, of any
judgment, decree, order, law, license, rule or regulation pertaining to
environmental matters, including without limitation, those arising under the
Resource Conservation and Recovery Act ("RCRA"), the Comprehensive Environmental
Response, Compensation and Liability Act of 1980 as amended ("CERCLA"), the
Superfund Amendments and Reauthorization Act of 1986 ("SARA"), the Federal Clean
Water Act, the Federal Clean Air Act, the Toxic Substances Control Act, or any
state or local statute, regulation, ordinance, order or decree relating to
health, safety or the environment (hereinafter "Environmental Laws"), which
violation or alleged violation has, or its remediation would have, by itself or
when aggregated with all such other violations or alleged violations, a material
adverse effect on the business, assets or financial condition of the Borrower
and its Subsidiaries, taken as a whole, or constitutes a Disqualifying
Environmental Event with respect to any of the Borrowing Base Properties.

                   (b) None of the Borrower, BPI or any of their respective
Subsidiaries has received written notice from any third party, including,
without limitation, any federal, state or local governmental authority, (i) that
it has been identified by the United States Environmental Protection Agency
("EPA) as a potentially responsible party under CERCLA with respect to a site
listed on the National Priorities List, 40 C.F.R. Part 300 Appendix B (1986),
(ii) that any hazardous waste, as defined by 42 U.S.C. Section 9601(5), any
hazardous substances as defined by 42 U.S.C. Section 9601(14), any pollutant or
contaminant as defined by 42 U.S.C. Section 9601(33) or any toxic substances,
oil or hazardous materials or other chemicals or substances regulated by any
Environmental Laws ("Hazardous Substances") which it has generated, transported
or disposed of have been found at any site at which a federal, state or local
agency or other third party has conducted or has ordered that the Borrower, BPI
or any of their respective Subsidiaries conduct a remedial investigation,
removal or other response action pursuant to any Environmental Law, or (iii)
that it is or shall be a named party to any claim, action, cause of action,
complaint, or legal or administrative proceeding (in each case, contingent or
otherwise) arising out of any third party's incurrence of costs, expenses,
losses or damages of any kind whatsoever in connection with the release of
Hazardous Substances, which event described in any such notice would have a
material adverse effect on the business, assets or financial condition of the
Borrower and its Subsidiaries, taken as a whole, or constitutes a Disqualifying
Environmental Event with respect to any of the Borrowing Base Properties.

                   (c) (i) No portion of the Real Estate Assets has been used
for the handling, processing, storage or disposal of Hazardous Substances except
in material

                                      -62-
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accordance with applicable Environmental Laws; and no underground tank or other
underground storage receptacle for Hazardous Substances is located on any
portion of any Real Estate Assets except in material accordance with applicable
Environmental Laws, (ii) in the course of any activities conducted by the
Borrower, BPI, their respective Subsidiaries or the operators of their
respective properties or any ground or space tenants on any Real Estate Asset,
no Hazardous Substances have been generated or are being used on such Real
Estate Asset except in material accordance with applicable Environmental Laws,
(iii) there has been no present or, to the best of Borrower's knowledge, past
releasing, spilling, leaking, pumping, pouring, emitting, emptying, discharging,
injecting, escaping, disposing or dumping (a "Release") or threatened Release of
Hazardous Substances on, upon, into or from the Real Estate Assets in violation
of applicable Environmental Laws, (iv) to the best of Borrower's knowledge,
there have been no Releases in violation of applicable Environmental Laws upon,
from or into any real property in the vicinity of any of the Real Estate Assets
which, through soil or groundwater contamination, may have come to be located on
such Real Estate Asset, and (v) to the best of Borrower's Knowledge, any
Hazardous Substances that have been generated on any of the Real Estate Assets
during ownership thereof by the Borrower, BPI, their respective Subsidiaries or
the operations of their respective properties have been transported off-site
only in compliance with all applicable Environmental Laws; any of which events
described in clauses (i) through (v) above would have a material adverse effect
on the business, assets or financial condition of BPLP, BPI, or taken as a
whole, the BP Group, or constitutes a Disqualifying Environmental Event with
respect to any of the Borrowing Base Properties. Notwithstanding that the
representations contained herein are limited to the knowledge of the Borrower,
any such limitation shall not affect the covenants specified in Section 8.11 or
elsewhere in this Agreement.

                   (d) None of the Borrower, BPI or any of the Real Estate
Assets is subject to any applicable Environmental Law requiring the performance
of Hazardous Substances site assessments, or the removal or remediation of
Hazardous Substances, or the giving of notice to any governmental agency or the
recording or delivery to other Persons of an environmental disclosure document
or statement, by virtue of the transactions set forth herein and contemplated
hereby, or as a condition to the effectiveness of any other transactions
contemplated hereby.

    Section 7.19.  SUBSIDIARIES. SCHEDULE 7.19 sets forth, as of the Closing
Date, all of the respective Subsidiaries of BPLP, each other Borrower and BPI.

    Section 7.20.  LOAN DOCUMENTS. All of the representations and warranties by
or on behalf of the Borrower and BPI and their respective Subsidiaries made in
this Agreement and in the other Loan Documents or any document or instrument
delivered to the Agent or the Banks pursuant to or in connection with any of
such Loan Documents are true and correct in all material respects and do not
include any untrue statement of a material fact or omit to state a material fact
required to be stated or necessary to make such representations and warranties
not materially misleading.

                                      -63-
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    Section 7.21.  REIT STATUS. BPI has not taken any action that would prevent
it from maintaining its qualification as a REIT for its tax years ended December
31, 1997, December 31, 1998, December 31, 1999, December 31, 2000, December 31,
2001 or December 31, 2002 or from maintaining such qualification at all times
during the term of this Agreement.

    Section 8.     AFFIRMATIVE COVENANTS OF THE BORROWER AND BPI. The Borrower
for itself and on behalf of BPI and their respective Subsidiaries (if and to the
extent expressly included in subsections contained in this Section 8) covenants
and agrees that, so long as any Loan, Letter of Credit or Note is outstanding or
any Bank has any obligation to make any Loans or any Bank has any obligation to
issue, extend or renew any Letters of Credit:

    Section 8.1.   PUNCTUAL PAYMENT. The Borrower will duly and punctually pay
or cause to be paid the principal and interest on the Loans and all interest,
fees, charges and other amounts provided for in this Agreement and the other
Loan Documents, all in accordance with the terms of this Agreement and the
Notes, and the other Loan Documents.

    Section 8.2.   MAINTENANCE OF OFFICE. Each of the Borrower and BPI will
maintain its chief executive office in Boston, Massachusetts, or at such other
place in the United States of America as each of them shall designate by written
notice to the Agent to be delivered within fifteen (15) days of any change of
chief executive office, where, subject to Section 22, notices, presentations and
demands to or upon the Borrower and BPI in respect of the Loan Documents may be
given or made.

    Section 8.3.   RECORDS AND ACCOUNTS. Each of the Borrower and BPI will (a)
keep, and cause each of its Subsidiaries to keep, true and accurate records and
books of account in which full, true and correct entries in all material
respects will be made in accordance with GAAP and (b) maintain adequate accounts
and reserves for all taxes (including income taxes), contingencies, depreciation
and amortization of its properties and the properties of its Subsidiaries; all
of such reserves may be unfunded.

    Section 8.4.   FINANCIAL STATEMENTS, CERTIFICATES AND INFORMATION. The
Borrower will deliver and cause BPI to deliver (as applicable) to the Agent
(with copies to the Agent for each Bank):

                   (a) as soon as practicable, but in any event not later than
ninety (90) days after the end of each fiscal year of BPI, the audited
consolidated balance sheet of BPI and its Subsidiaries at the end of such year,
and the related audited consolidated statements of income, changes in
shareholder's equity and cash flows for the year then ended, in each case,
setting forth in comparative form the figures as of the end of and for the
previous fiscal year and all such statements to be in reasonable detail,
prepared in accordance with GAAP, and, in each case, accompanied by an auditor's
report prepared

                                      -64-
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without qualification by the Accountants (and the Borrower also shall deliver
the foregoing for BPLP on a consolidated basis);

                   (b) as soon as practicable, but in any event not later than
forty-five (45) days after the end of each of its March 31, June 30 and
September 30 fiscal quarters, copies of the unaudited consolidated balance sheet
of BPI and its Subsidiaries, as at the end of such quarter, and the related
unaudited consolidated statements of income, changes in shareholders' equity and
cash flows for the portion of BPI's fiscal year then elapsed, all in reasonable
detail and prepared in accordance with GAAP (which may be provided by inclusion
in the Form 10-Q of BPI filed with the SEC for such period provided pursuant to
clause (i) below), together with a certification by the principal financial or
accounting officer of the Borrower and BPI that the information contained in
such financial statements fairly presents the financial position of BPI and its
Subsidiaries on the date thereof (subject to year-end adjustments none of which
shall be materially adverse) (and the Borrower also shall deliver the foregoing
for BPLP on a consolidated basis);

                   (c) Upon the request of the Agent and as soon as practicable,
but in any event not later than ninety (90) days after the end of each of its
fiscal years, statements of Net Operating Income and outstanding Indebtedness as
at the end of such fiscal year and for the fiscal year then ended in respect of
each Real Estate Asset (including each Borrowing Base Property), each prepared
in accordance with GAAP consistent with the definitions of Net Operating Income
and outstanding Indebtedness used in this Agreement and a summary rent roll in
respect of each Borrowing Base Property, in each case certified by the chief
financial or accounting officer of the Borrower as true and correct in all
material respects;

                   (d) Upon the request of the Agent and as soon as practicable,
but in any event not later than forty-five (45) days after the end of each of
the fiscal quarters of the Borrower, (1) copies of the unaudited statements of
Net Operating Income and outstanding Indebtedness as at the end of such quarter
and for the portion of the fiscal year then elapsed in respect of each Real
Estate Asset (including each Borrowing Base Property), each prepared in
accordance with GAAP consistent with the definitions of Net Operating Income and
outstanding Indebtedness used in this Agreement and certified by the chief
financial or accounting officer of the Borrower to present fairly the Net
Operating Income and outstanding Indebtedness in respect of each such Real
Estate Asset and (ii) an occupancy analysis in respect of each Real Estate Asset
(including each Borrowing Base Property) certified by the chief financial
officer of the Borrower to be true and complete in all material respects;

                   (e) simultaneously with the delivery of the financial
statements referred to in subsections (a) and (b) above, a statement in the form
of EXHIBIT C-2 hereto signed by the chief financial or accounting officer of the
Borrower and (if applicable) reconciliations to reflect changes in GAAP since
the date of such financial statements;

                                      -65-
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                   (f) promptly as they become available, a copy of each report
(including any so-called management letters) submitted to the Borrower, BPI or
any of their respective subsidiaries by the Accountants in connection with each
annual audit of the books of the Borrower, BPI or such Subsidiary by such
Accountants or in connection with any interim audit thereof pertaining to any
phase of the business of the Borrower, BPI or any such Subsidiary;

                   (g) contemporaneously with (or promptly after) the filing or
mailing thereof, copies of all material of a financial nature sent to the
holders of any Indebtedness of the Borrower (other than the Loans) for borrowed
money, to the extent that the information or disclosure contained in such
material refers to or could reasonably be expected to have a material adverse
effect on the business, assets, financial condition or prospects, or operations
of BPLP, BPI or, taken as a whole, the BP Group;

                   (h) contemporaneously with the filing or mailing thereof,
copies of all material of a financial nature filed with the SEC or sent to the
stockholders of BPI;

                   (i) as soon as practicable, but in any event not later than
ninety (90) days after the end of each fiscal year of BPI, copies of the Form
10-K statement filed by BPI with the SEC for such fiscal year, and as soon as
practicable, but in any event not later than fifty (50) days after the end of
each fiscal quarter of BPI copies of the Form 10-Q statement filed by BPI with
the SEC for such fiscal quarter, PROVIDED that, in either case, if the SEC has
granted an extension for the filing of such statements, BPI shall deliver such
statements to the Agent within ten (10) days after the filing thereof with the
SEC;

                   (j) from time to time such other financial data and
information about the Borrower, BPI, their respective Subsidiaries, the Real
Estate Assets and the Partially-Owned Real Estate Holding Entities as the Agent
or any Bank (through the Agent) may reasonably request, including without
limitation complete rent rolls, existing environmental reports, and insurance
certificates with respect to the Real Estate Assets (including the Borrowing
Base Properties);

                   (k) in the case of the Borrower and BPI, as soon as
practicable, but in any event not later than ninety (90) days after the end of
each of their respective fiscal years, PRO FORMA projections for the next three
fiscal years;

                   (l) together with the financial statements delivered pursuant
to Section 8.4(a), a certification by the chief financial or accounting officer
of the Borrower of the state and federal taxable income of BPI and its
Subsidiaries as of the end of the applicable fiscal year; and

                   (m) in the event that the definition of "funds from
operations" is revised by the Board of Governors of the National Association of
Real Estate Investment

                                      -66-
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Trusts, a report, certified by the chief financial or accounting officer of the
Borrower, of the "funds from operations" of the Borrower based on the definition
as in effect on the date of this Agreement and based on the definition as so
revised from time to time, which such report shall be delivered to the Agent
(with copies to the Agent for each Bank) with the financial statements required
to be delivered pursuant to Section 8.4(b) above; and

                   (n) as soon as practicable, but in any event not later than
ninety (90) days after the end of the fiscal year of BPLP, the unaudited balance
sheet of BPLP at the end of each such year, and the related unaudited statements
of income, changes in partners' capital and cash flows for the year then ended,
in each case setting forth in comparative form the figures for the previous
fiscal year and all such statements to be in reasonable detail, prepared in
accordance with GAAP, together with a certification by the principal financial
or accounting officer of BPLP that the information contained in such financial
statements fairly presents the financial position of BPLP on the date thereof,
and as soon as practicable, but in any event not later than forty-five (45) days
after the end of each of the March 31, June 30 and September 30 fiscal quarters
of BPLP, the unaudited balance sheet of BPLP at the end of each such quarter,
and the related unaudited statements of income, changes in partners' capital and
cash flows for the quarter then ended, in each case setting forth in comparative
form the figures for the previous fiscal quarter and all such statements to be
in reasonable detail, prepared in accordance with GAAP, together with a
certification by the principal financial or accounting officer of BPLP that the
information contained in such financial statements fairly presents the financial
position of BPLP on the date thereof (subject to year-end adjustments none of
which shall be materially adverse).

    Section 8.5.   NOTICES.

                   (a) DEFAULTS. The Borrower will, and will cause BPI, as
applicable, to, promptly after obtaining knowledge of the same, notify the Agent
in writing (with copies to the Agent for each Bank) of the occurrence of any
Default or Event of Default or Non-Material Breach. If any Person shall give any
notice or take any other action in respect of (x) a claimed Default (whether or
not constituting an Event of Default) under this Agreement or (y) a claimed
failure by the Borrower, BPI or any of their respective Subsidiaries, as
applicable, to comply with any term, condition or provision of or under any
note, evidence of Indebtedness, indenture or other obligation in excess of
$10,000,000, individually or in the aggregate, to which or with respect to which
any of them is a party or obligor, whether as principal or surety, and such
failure to comply would permit the holder of such note or obligation or other
evidence of Indebtedness to accelerate the maturity thereof, which acceleration
would have a material adverse effect on BPLP, BPI or, taken as a whole, the BP
Group or the Borrower shall forthwith give written notice thereof to the Agent
and each of the Banks, describing the notice or action and the nature of the
claimed failure to comply.

                                      -67-
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                   (b) ENVIRONMENTAL EVENTS. The Borrower will, and will cause
BPI to, promptly give notice in writing to the Agent (with copies to the Agent
for each Bank) (i) upon Borrower's or BPI's obtaining knowledge of any material
violation (as determined by the Borrower or BPI in the exercise of its
reasonable discretion) of any Environmental Law regarding any Real Estate Asset
or Borrower's or BPI's operations, (ii) upon Borrower's or BPI's obtaining
knowledge of any known Release of any Hazardous Substance at, from, or into any
Real Estate Asset which it reports in writing or is reportable by it in writing
to any governmental authority and which is material in amount or nature or which
could materially affect the value of such Real Estate Asset, (iii) upon
Borrower's or BPI's receipt of any notice of material violation of any
Environmental Laws or of any material Release of Hazardous Substances in
violation of any Environmental Laws or any matter that may be a Disqualifying
Environmental Event with respect to any of the Borrowing Base Properties,
including a notice or claim of liability or potential responsibility from any
third party (including without limitation any federal, state or local
governmental officials) and including notice of any formal inquiry, proceeding,
demand, investigation or other action with regard to (A) Borrower's or BPI's or
any other Person's operation of any Real Estate Asset, (B) contamination on,
from or into any Real Estate Asset, or (C) investigation or remediation of
off-site locations at which Borrower or BPI or any of its predecessors are
alleged to have directly or indirectly disposed of Hazardous Substances, or (iv)
upon Borrower's or BPI's obtaining knowledge that any expense or loss has been
incurred by such governmental authority in connection with the assessment,
containment, removal or remediation of any Hazardous Substances with respect to
which Borrower or BPI or any Partially-Owned Real Estate Entity may be liable or
for which a lien may be imposed on any Real Estate Asset; any of which events
described in clauses (i) through (iv) above would have a material adverse effect
on the business, assets or financial condition of the Borrower and its
Subsidiaries, taken as a whole, or constitutes a Disqualifying Environmental
Event with respect to any of the Borrowing Base Properties. As of the date
hereof, the Borrower has notified the Agent and the Banks of the matters
referenced on SCHEDULE 8.5(B), to the extent such matters are disclosed in the
Form 10-K referred to therein.

                   (c) NOTIFICATION OF CLAIMS AGAINST BORROWING BASE PROPERTIES.
The Borrower will, and will cause each Subsidiary to, promptly upon becoming
aware thereof, notify the Agent in writing (with copies to the Agent for each
Bank) of any setoff, claims, withholdings or other defenses to which any of the
Borrowing Base Properties are subject, which (i) would have a material adverse
effect on (x) the business, assets or financial condition of BPLP, BPI or, taken
as a whole, the BP Group, or (y) the value of any such Borrowing Base Property,
or (ii) with respect to such Borrowing Base Property, constitute a Disqualifying
Environmental Event, a Disqualifying Structural Event or a Lien subject to the
bonding or insurance requirement of Section 9.2(viii).

                   (d) NOTICE OF LITIGATION AND JUDGMENTS. The Borrower will,
and will cause BPI and their respective Subsidiaries, to give notice to the
Agent in writing (with copies to the Agent for each Bank) within fifteen (15)
days of becoming aware of any

                                      -68-
<Page>

litigation or proceedings threatened in writing or any pending litigation and
proceedings an adverse determination in which could materially affect BPLP, BPI
or taken as a whole, the BP Group, or any Borrowing Base Property or to which
the Borrower, BPI or any of their respective Subsidiaries is or is to become a
party involving an uninsured claim against the Borrower, BPI or any of their
respective Subsidiaries that could reasonably be expected to have a materially
adverse effect on BPLP, BPI or, taken as a whole, the BP Group, the respective
properties, business, assets, financial condition or prospects or on the value
or operation of the Borrowing Base Properties and stating the nature and status
of such litigation or proceedings. The Borrower will, and will cause each of BPI
and their respective Subsidiaries to, give notice to the Agent and each of the
Banks, in writing, in form and detail reasonably satisfactory to the Agent and
each of the Banks, within ten (10) days of any judgment not covered by
insurance, final or otherwise, against the Borrower, BPI or any of such
Subsidiaries in an amount in excess of $5,000,000.

                   (e) ACQUISITION OF REAL ESTATE ASSETS. The Borrower shall
notify the Agent (with copies to the Agent for each Bank) in its financial
reports delivered pursuant to Section Section 8.4(a) and (b) of the acquisition
of Real Estate Assets during the applicable quarter by the Borrower or any other
member of the BP Group (other than BPI) (whether or not such acquisition was
made with proceeds of the Loans), which notice shall include, at the Agent's
request, with respect to each such Real Estate Asset, its address, a brief
description and recent photograph, a rent roll summary, a PRO FORMA and historic
(if available) income statement and a summary of the key business terms of such
acquisition, PROVIDED that the failure of the Borrower to provide such notice to
the Agent shall not constitute a Default or Event of Default hereunder.

                   (f) INSOLVENCY EVENTS. The Borrower shall notify the Agent in
writing (with copies to the Agent for each Bank) promptly after the occurrence
of any of the events described in Section 14.1(g) or (h) with respect to any
member of the BP Group other than BPLP and BPI.

    Section 8.6.   EXISTENCE OF BORROWER; MAINTENANCE OF PROPERTIES. The
Borrower will do or cause to be done all things necessary to, and shall,
preserve and keep in full force and effect its respective existence in its
jurisdiction of organization and will do or cause to be done all things
necessary to preserve and keep in full force all of its respective rights and
franchises and those of its respective Subsidiaries each of which in the good
faith judgment of BPLP may be necessary to properly and advantageously conduct
the businesses conducted by it. The Borrower (a) will cause all necessary
repairs, renewals, replacements, betterments and improvements to be made to all
Real Estate Assets owned or controlled by it, all as in the judgment of the
Borrower may be necessary so that the business carried on in connection
therewith may be properly and advantageously conducted at all times, subject to
the terms of the applicable Leases and partnership agreements or other entity
charter documents, and in any event, will keep all of the Real Estate Assets
(for so long as such Real Estate Assets are owned by the Borrower or any of its
Subsidiaries) in a condition consistent with the Real Estate Assets currently
owned or

                                      -69-
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controlled by the Borrower or its Subsidiaries, (b) will cause all of its other
properties and those of its Subsidiaries (to the extent controlled by the
Borrower) used or useful in the conduct of its business or the business of its
Subsidiaries to be maintained and kept in good condition, repair and working
order and supplied with all necessary equipment, (c) will not permit BPI to
directly own or lease any Real Estate Asset (except only 100 East Pratt Street,
Baltimore, Maryland so long as all of the economic benefits of such Real Estate
Asset contractually flow to BPLP), and (d) will, and will cause each of its
Subsidiaries to continue to engage primarily in the businesses now conducted by
it and in related businesses, all of the foregoing to the extent necessary to
comply with the other terms and conditions set forth in this Agreement, and in
the case of clauses (a) and (b) above, except to the extent that the failure to
comply with the provisions thereof constitutes a Non-Material Breach.

    Section 8.7.   EXISTENCE OF BPI; MAINTENANCE OF REIT STATUS OF BPI;
MAINTENANCE OF PROPERTIES;. The Borrower will cause BPI to do or cause to be
done all things necessary to preserve and keep in full force and effect BPI's
existence as a Delaware corporation. The Borrower will cause BPI at all times
(i) to maintain its status as a REIT and not to take any action which could lead
to its disqualification as a REIT and (ii) to continue to be listed on a
nationally-recognized stock exchange. Without limitation of Section 9.3(f), the
Borrower will cause BPI not to engage in any business other than the business of
acting as a REIT and serving as the general partner and limited partner of the
Borrower, and as a member, partner or stockholder of Subsidiaries of the
Borrower, including Boston Properties LLC (PROVIDED that BPI's percentage equity
interest in any such Subsidiary shall not exceed 1%), and matters directly
relating thereto, and shall cause BPI to (x) conduct all or substantially all of
its business operations through the Borrower or through subsidiary partnerships
or other entities in which the Borrower owns at least 99% of the economic
interests and (y) own no real property or material personal property other than
(1) through its ownership interests in the Borrower and its Subsidiaries,
including Boston Properties LLC, in compliance with the terms hereof, and (2)
contracts and agreements of the nature described in Schedule 9.1(e). The
Borrower will cause BPI (a) to cause all of its properties and those of its
Subsidiaries used or useful in the conduct of its business or the business of
its Subsidiaries to be maintained and kept in good condition, repair and working
order, and supplied with all necessary equipment, (b) to cause to be made all
necessary repairs, renewals, replacements, betterments and improvements thereof,
all as in the judgment of BPI may be necessary so that the business carried on
in connection therewith may be properly and advantageously conducted at all
times and (c) to cause each of its Subsidiaries to continue to engage primarily
in the businesses now conducted by it and in related businesses, in each case
under clauses (a), (b) and (c) above to the extent, in the good faith judgment
of BPI, necessary to properly and advantageously conduct the businesses being
conducted by it.

    Section 8.8.   INSURANCE. The Borrower will, and will cause BPI to, maintain
with respect to its properties, and will cause each of its Subsidiaries to
maintain with financially sound and reputable insurers, insurance with respect
to such properties and its

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business against such casualties and contingencies as shall be in accordance
with the general practices of businesses engaged in similar activities in
similar geographic areas and in amounts, containing such terms, in such forms
and for such periods as may be reasonable and prudent, unless any failure to do
so does not relate to BPLP or BPI and is a Non-Material Breach.

    Section 8.9.   TAXES. The Borrower will, and will cause BPI and each of
their respective Subsidiaries to, pay or cause to be paid real estate taxes,
other taxes, assessments and other governmental charges against the Real Estate
Assets before the same become delinquent and will duly pay and discharge, or
cause to be paid and discharged, before the same shall become overdue, all
taxes, assessments and other governmental charges imposed upon its sales and
activities, or any part thereof, or upon the income or profits therefrom, as
well as all claims for labor, materials, or supplies that if unpaid might by law
become a lien or charge upon any of the Real Estate Assets, unless any failure
to do so does not relate to BPLP or BPI and is a Non-Material Breach; PROVIDED
that any such tax, assessment, charge, levy or claim need not be paid if the
validity or amount thereof shall currently be contested in good faith by
appropriate proceedings and if the Borrower or BPI shall have set aside on its
books adequate reserves with respect thereto; and PROVIDED further that the
Borrower or BPI will pay all such taxes, assessments, charges, levies or claims
forthwith prior to the consummation of proceedings to foreclose any lien that
may have attached as security therefor. Promptly upon request by the Agent if
required for bank regulatory compliance purposes or similar bank purposes, the
Borrower will provide evidence of the payment of real estate taxes, other taxes,
assessments and other governmental charges against the Real Estate Assets in the
form of receipted tax bills or other form reasonably acceptable to the Agent, or
evidence of the existence of applicable contests as contemplated herein.

    Section 8.10. INSPECTION OF PROPERTIES AND BOOKS. (a) Subject to the rights
of tenants to limit or prohibit such access, as denoted in the applicable
leases, the Borrower will, and will cause BPI to, permit the Agent or any of the
Banks' other designated representatives upon no less than 24 hours notice (which
notice may be given orally or in writing), to visit and inspect any of the
properties of the Borrower, BPI or any of their respective Subsidiaries to
examine the books of account of the Borrower, BPI and their respective
Subsidiaries (and to make copies thereof and extracts therefrom) and to discuss
the affairs, finances and accounts of the Borrower, BPI and their respective
Subsidiaries with, and to be advised as to the same by, its officers, all at
such reasonable times and intervals as the Agent may reasonably request;
PROVIDED that, so long as no Event of Default has occurred and is continuing,
the Borrower shall only be responsible for the costs and expenses incurred by
the Agent in connection with such inspections.

                   (b) The Borrower hereby agrees that each of the Banks and the
Agent (and each of their respective, and their respective affiliates',
employees, officers, directors, agents and advisors (collectively,
"Representatives") is, and has been from the commencement of discussions with
respect to the facility established by the Agreement

                                      -71-
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(the "Facility"), permitted to disclose to any and all Persons, without
limitation of any kind, the structure and tax aspects (as such terms are used in
Code sections 6011 and 6111) of the Facility, and all materials of any kind
(including opinions or other tax analyses) that are or have been provided to
such Bank or the Agent related to such structure and tax aspects. In this
regard, each of the Banks and the Agent acknowledges and agrees that its
disclosure of the structure or tax aspects of the Facility is not limited in any
way by an express or implied understanding or agreement, oral or written
(whether or not such understanding or agreement is legally binding).
Furthermore, each of the Banks and the Agent acknowledges and agrees that it
does not know or have reason to know that its use or disclosure of information
relating to the structure or tax aspects of the Facility is limited in any other
manner (such as where the Facility is claimed to be proprietary or exclusive)
for the benefit of any other Person. Notwithstanding the foregoing (i) the Banks
and the Agent shall not disclose any materials or information of any kind or
nature whatsoever which are not specifically permitted to be disclosed in
accordance with the terms of this subparagraph (b) and (ii) in the event of any
change, amendment, modification or clarification of Code sections 6011 and/or
6111 (or any other applicable Section) or any Regulations promulgated
thereunder, or the issuance by any Person of any guidance on which the Banks,
the Agent and the Representatives are entitled to rely or are otherwise bound by
(including, by way of example only, private letter rulings), which in any way
limits or restricts what may be disclosed pursuant to the terms of this
paragraph, or otherwise establishes that such Code sections do not, or are not
intended to, apply to loan facilities such as the Facility (or other similar
transactions), the terms of this subparagraph (b) shall be deemed modified
thereby. In this regard, the Banks and the Agent intend that this transaction
will not be a "confidential transaction" under Code sections 6011, 6111 or 6112,
and the regulations promulgated thereunder.

                   (c) Notwithstanding anything to the contrary herein
(including, without limitation, the provisions of subparagraph (b) above),
neither the Agent nor any Bank may disclose to any Person any information that
constitutes material non-public information regarding the Borrower or its
securities for purposes of Regulation FD of the Securities and Exchange
Commission or any other federal or state securities laws (it being acknowledged
and agreed that the provisions of this Section 8.10 with respect to such
information are reasonably necessary to comply with said Regulation FD and/or
such other federal and state securities laws) (such information referred to
collectively herein as the "BORROWER INFORMATION"), except that each of the
Agent and each of the Banks may disclose Borrower Information (i) to any other
Bank, (ii) to any other person if reasonably incidental to the administration of
the Loans, (iii) upon the order of any court or administrative agency, (iv) upon
the request or demand of any regulatory agency or authority, (v) which has been
publicly disclosed other than as a result of a disclosure by the Agent or any
Bank which is not permitted by this Agreement, (vi) in connection with any
litigation to which the Agent, any Bank, or any other Representative may be a
party, (vii) to the extent reasonably required in connection with the exercise
of any remedy hereunder, (viii) to the Agent's or such Bank's Affiliates, legal
counsel and independent

                                      -72-
<Page>

auditors or other Represenatives, and (ix) to any actual or proposed participant
or Eligible Assignee of all or part of its rights hereunder.

                   (d) Each of the Banks and the Agent hereby agrees that the
Borrower (and its, and its affiliates', employees, officers, directors, advisors
and agents (collectively "Borrower Representatives") is, and has been from the
commencement of discussions with respect to the Facility, permitted to disclose
to any and all Persons, without limitation of any kind, the structure and tax
aspects (as such terms are used in Code sections 6011 and 6111) of the Facility,
and all materials of any kind (including opinions or other tax analyses) that
are or have been provided to the Borrower related to such structure and tax
aspects. In this regard, the Borrower acknowledges and agrees that its
disclosure of the structure or tax aspects of the Facility is not limited in any
way by an express or implied understanding or agreement, oral or written
(whether or not such understanding or agreement is legally binding).
Furthermore, each of the Borrower, each Bank and the Agent acknowledges and
agrees that it does not know or have reason to know that its use or disclosure
of information relating to the structure or tax aspects of the Facility is
limited in any other manner (such as where the Facility is claimed to be
proprietary or exclusive) for the benefit of any other Person.

                   (e) The provisions of this Section 8.10 supersede any
confidentiality obligations of the Borrower, the Agent or any of the Banks
relating to the Facility under any agreements between or among the Borrower and
the Agent and/or the Banks, as applicable. The parties hereto agree that any
such confidentiality obligations shall be deemed void AB INITIO.

    Section 8.11.  COMPLIANCE WITH LAWS, CONTRACTS, LICENSES, AND PERMITS. The
Borrower will, and will cause BPI to, comply with, and will cause each of their
respective Subsidiaries to comply with (a) all applicable laws and regulations
now or hereafter in effect wherever its business is conducted, including,
without limitation, all Environmental Laws and all applicable federal and state
securities laws, (b) the provisions of its partnership agreement or corporate
charter and other charter documents and by-laws, as applicable, (c) all material
agreements and instruments to which it is a party or by which it or any of its
properties may be bound (including the Real Estate Assets and the Leases) and
(d) all applicable decrees, orders, and judgments, unless such non-compliance
does not relate to BPLP or BPI and constitutes a Non-Material Breach. If at any
time while any Loan or Note or Letter of Credit is outstanding or the Banks have
any obligation to make Loans or issue Letters of Credit hereunder, any Permit
shall become necessary or required in order that the Borrower may fulfill any of
its obligations hereunder, the Borrower and BPI and their respective
Subsidiaries will immediately take or cause to be taken all reasonable steps
within the power of the Borrower or BPI, as applicable, to obtain such Permit
and furnish the Agent with evidence thereof.

    Section 8.12.  USE OF PROCEEDS. Subject at all times to the other provisions
of this Agreement, the Borrower will use the proceeds of the Loans solely for
working capital

                                      -73-
<Page>

and general corporate purposes. It is agreed by the Banks that, from time to
time, the Borrower may request proceeds of the Loans be used to refinance
certain secured mortgage Indebtedness of the Borrower, in which event, a portion
of the Loans equal to the amount of the advances made hereunder in connection
with such refinancing may, at Borrower's election, be secured by the refinanced
mortgage (a "Refinancing Mortgage"). Any such Refinancing Mortgage would be (i)
required to be in form and substance reasonably satisfactory to the Agent, (ii)
subject to customary terms and conditions reasonably satisfactory to the Agent,
(iii) amended and restated to provide for economic and other terms which are
identical to those of the Loans (e.g., the maturity date shall be amended to be
the Maturity Date hereunder and the interest rate and payment terms will be
amended to be the same as those hereunder, it being further acknowledged that
such modified interest rate may be based upon either a Revolving Credit Loan or
a Bid Rate Loan calculation, as elected by the Borrower pursuant to the terms
hereof) and (iv) subject to being released or transferred by the Agent at the
request of the Borrower. In addition, in connection with each Refinancing
Mortgage, the Agent would agree to provide, at the request of Borrower,
subordination, non-disturbance and attornment agreements in form and substance
reasonably satisfactory to Agent. No Real Estate Asset that is subject to a
Refinancing Mortgage will qualify as an Unencumbered Asset hereunder.

    Section 8.13.  ADDITION OF BORROWING BASE PROPERTY. Prior to the addition of
any Real Estate Asset to the Borrowing Base as a Borrowing Base Property, the
Borrower shall promptly deliver to the Agent (i) the Joinder Documents
(including the documents, instruments, certificates and agreements required
thereby). Upon satisfaction of the requirements of this Section 8.13, and
subject to the compliance of any such additional Borrowing Base Property with
the Borrowing Base Conditions, such Real Estate Asset shall be included as a
Borrowing Base Property.

    Section 8.14.  ADDITIONAL BORROWERS; SOLVENCY OF BORROWERS; REMOVAL OF
BORROWERS.

                   (a) If, after the Closing Date, BPLP wishes to designate as a
Borrowing Base Property a Real Estate Asset that otherwise qualifies as a
Borrowing Base Property but is owned or ground-leased by a Person other than the
Borrower, BPLP shall cause such Person (which Person must be a Wholly-owned
Subsidiary) to become a party to this Agreement and the other applicable Loan
Documents prior to such Real Estate Asset becoming a Borrowing Base Property
hereunder. The liability of each Borrower which is from time to time a Borrower
hereunder shall be joint and several with all other Borrowers for all
Obligations for so long as such Borrower is a Borrower hereunder (PROVIDED that
BPLP shall at all times be a Borrower hereunder). At any time and from time to
time but only for so long as no Default or Event of Default shall then exist,
BPLP may notify Agent, in writing (each, a "Release Notice"), that one (1) or
more Borrowing Base Properties are to be removed from the Borrowing Base. Such
Release Notice shall be accompanied by a Certificate of Compliance in the form
of EXHIBIT C-4, evidencing compliance. Immediately upon receipt of such Release
Notice and Certificate

                                      -74-
<Page>

of Compliance, such Borrowing Base Properties (each, a "Released Property")
shall be removed from the Borrowing Base and any Wholly-owned Subsidiary which
is the owner of a Released Property and which is then a Borrower (other than
BPLP) hereunder shall be released from its obligations hereunder (including the
Obligations), PROVIDED, HOWEVER, that any such release shall only be effective
as to Obligations arising after the applicable Release Notice (and the
Certificate of Compliance evidencing compliance) is received by Agent. BPLP will
not permit any Borrower (other than BPLP) that owns or ground leases any
Borrowing Base Property to have any Subsidiaries unless such Subsidiary's
business, obligations and undertakings are exclusively related to the business
of such Borrower.

                   (b) Each Borrower and BPI shall remain solvent at all times,
unless such failure to remain solvent does not relate to BPLP or BPI and is a
Non-Material Breach.

    Section 8.15.  FURTHER ASSURANCES. The Borrower will, and will cause BPI to,
cooperate with, the Agent and the Banks and execute such further instruments and
documents as the Banks or the Agent shall reasonably request to carry out to
their satisfaction the transactions contemplated by this Agreement and the other
Loan Documents.

    Section 8.16.  INTEREST RATE PROTECTION. In the event that the Borrower's
floating rate Indebtedness at any time exceeds forty-five percent (45%) of
Consolidated Total Indebtedness, the Borrower shall, upon the Agent's written
request (an "Agent Notice"), maintain in effect interest rate protection
arrangements (by means of hedging techniques or vehicles such as interest rate
swaps, interest rate caps, interest rate corridors or interest rate collars, in
each case to be capped at a rate reasonably satisfactory to the Agent and the
Majority Banks and otherwise in form and substance reasonably satisfactory to
the Agent) for a tenor and in an amount reasonably satisfactory to the Agent and
the Majority Banks, provided that the amount of interest rate protection
required shall not exceed, in any event, the amount of the Borrower's floating
rate Indebtedness which is in excess of forty-five percent (45%) of Consolidated
Total Indebtedness. Once obtained, the Borrower shall maintain such arrangements
in full force and effect as provided therein, and shall not, without the
approval of the Majority Banks, modify, terminate, or transfer such arrangements
during the period in which the Borrower's floating rate Indebtedness exceeds
forty-five percent (45%) of Consolidated Total Indebtedness with respect to any
specific related Agent Notice. The Borrower may, at its option, enter into
additional interest rate protection arrangements permitted pursuant to Section
9.3.

    Section 8.17.  ENVIRONMENTAL INDEMNIFICATION. The Borrower covenants and
agrees that it will indemnify and hold the Agent and each Bank, and each of
their respective Affiliates, harmless from and against any and all claims,
expense, damage, loss or liability incurred by the Agent or any Bank (including
all reasonable costs of legal representation incurred by the Agent or any Bank,
but excluding, as applicable, for the Agent or a Bank any claim, expense,
damage, loss or liability as a result of the gross

                                      -75-
<Page>

negligence or willful misconduct of the Agent or such Bank or any of their
respective Affiliates) relating to (a) any Release or threatened Release of
Hazardous Substances on any Real Estate Asset; (b) any violation of any
Environmental Laws with respect to conditions at any Real Estate Asset or the
operations conducted thereon; (c) the investigation or remediation of off-site
locations at which the Borrower, BPI or any of their respective Subsidiaries or
their predecessors are alleged to have directly or indirectly disposed of
Hazardous Substances; or (d) any action, suit, proceeding or investigation
brought or threatened with respect to any Hazardous Substances relating to Real
Estate Assets (including, but not limited to, claims with respect to wrongful
death, personal injury or damage to property). It is expressly acknowledged by
the Borrower that, notwithstanding the introductory paragraph of this Section 8,
this covenant of indemnification shall survive the repayment of the amounts
owing under the Notes and this Agreement and the termination of this Agreement
and the obligations of the Banks hereunder and shall inure to the benefit of the
Agent and the Banks and their respective Affiliates, their respective
successors, and their respective assigns under the Loan Documents permitted
under this Agreement.

    Section 8.18.  RESPONSE ACTIONS. The Borrower covenants and agrees that if
any Release or disposal of Hazardous Substances shall occur or shall have
occurred on any Real Estate Asset owned directly or indirectly by the Borrower
or BPI, in violation of applicable Environmental Laws, the Borrower will cause
the prompt containment and removal of such Hazardous Substances and remediation
of such wholly-owned Real Estate Asset as necessary to comply with all
Environmental Laws.

    Section 8.19.  ENVIRONMENTAL ASSESSMENTS. If the Agent in its good faith
judgment, after discussion with the Borrower and review of any environmental
reports provided by the Borrower, has reasonable grounds to believe that a
Disqualifying Environmental Event has occurred with respect to any one or more
of the Borrowing Base Properties, whether or not a Default or an Event of
Default shall have occurred, the Agent may, from time to time, for the purpose
of assessing and determining whether a Disqualifying Environmental Event has in
fact occurred, cause the Borrower to obtain one or more environmental
assessments or audits of such Borrowing Base Property prepared by a
hydrogeologist, an independent engineer or other qualified consultant or expert
approved by the Agent to evaluate or confirm (i) whether any Hazardous
Substances are present in the soil or water at such Borrowing Base Property and
(ii) whether the use and operation of such Borrowing Base Property complies with
all Environmental Laws. Environmental assessments may include without limitation
detailed visual inspections of such Borrowing Base Property including, without
limitation, any and all storage areas, storage tanks, drains, dry wells and
leaching areas, and, if and to the extent reasonable, appropriate and required
pursuant to applicable Environmental Laws, the taking of soil samples, surface
water samples and ground water samples, as well as such other investigations or
analyses as the Agent deems appropriate. All such environmental assessments
shall be at the sole cost and expense of the Borrower; provided, however, the
Agent may not require environmental assessments at the Borrower's expense, with
respect to any Borrowing

                                      -76-
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Base Property, more frequently than upon the occurrence of a Release on any
Borrowing Base Property.

    Section 8.20.  EMPLOYEE BENEFIT PLANS.

                   (a) NOTICE. The Borrower will, and will cause BPI to, notify
the Agent (with copies to the Agent for each Bank) within a reasonable period
after the establishment of any Employee Benefit Plan or Guaranteed Pension Plan
by any of them or any of their respective ERISA Affiliates other than those
disclosed in the SEC Filings and no Borrower will, or will permit BPI to,
establish any Employee Benefit Plan, Multiemployer Plan or Guaranteed Pension
Plan which could reasonably be expected to have a material adverse effect on
BPLP, BPI or, taken as a whole, the BP Group.

                   (b) IN GENERAL. Each Employee Benefit Plan maintained by the
Borrower, BPI or any of their respective ERISA Affiliates will be operated in
compliance in all material respects with the provisions of ERISA and, to the
extent applicable, the Code, including but not limited to the provisions
thereunder respecting prohibited transactions.

                   (c) TERMINABILITY OF WELFARE PLANS. With respect to each
Employee Benefit Plan maintained by the Borrower, BPI or any of their respective
ERISA Affiliates which is an employee welfare benefit plan within the meaning of
Section 3(l) or Section 3(2)(B) of ERISA, the Borrower, BPI, or any of their
respective ERISA Affiliates, as the case may be, has the right to terminate each
such plan at any time (or at any time subsequent to the expiration of any
applicable bargaining agreement) without liability other than liability to pay
claims incurred prior to the date of termination.

                   (d) UNFUNDED OR UNDERFUNDED LIABILITIES. The Borrower will
not, and will not permit BPI to, at any time, have accruing or accrued unfunded
or underfunded liabilities with respect to any Employee Benefit Plan, Guaranteed
Pension Plan or Multiemployer Plan, or permit any condition to exist under any
Multiemployer Plan that would create a withdrawal liability, which such
liability could, individually or in the aggregate, reasonably be expected to
have a material adverse effect on BPLP, BPI or, taken as a whole, the BP Group.

    Section 8.21.  NO AMENDMENTS TO CERTAIN DOCUMENTS. The Borrower will not,
and will not permit BPI to, at any time cause or permit its certificate of
limited partnership, agreement of limited partnership (including without
limitation the Agreement of Limited Partnership of the Borrower, articles of
incorporation, by-laws, operating agreement or other charter documents, as the
case may be, to be modified, amended or supplemented in any respect whatever,
without (in each case) the express prior written consent or approval of the
Agent, if such changes would affect BPI's REIT status or otherwise materially
adversely affect the rights of the Agent and the Banks hereunder or under any
other Loan Document.

                                      -77-
<Page>

    Section 9.     CERTAIN NEGATIVE COVENANTS OF THE BORROWER AND BPI. The
Borrower for itself and on behalf of BPI covenants and agrees that, so long as
any Loan, Letter of Credit or Note is outstanding or any Bank has any obligation
to make any Loans or any Bank has any obligation to issue, extend or renew any
Letters of Credit:

    Section 9.1.   RESTRICTIONS ON LIABILITIES. The Borrower and BPI may, and
may permit their respective Subsidiaries to, create, incur, assume, guarantee or
be or remain liable for, contingently or otherwise, any Liabilities other than
the specific Liabilities which are prohibited under this Section 9.1 (the
"Prohibited Liabilities"), it being agreed that neither the Borrower nor BPI
will, or will permit any Subsidiary to, create, incur, assume, guarantee or be
or remain liable for, contingently or otherwise, singularly or in the aggregate
for any of such Prohibited Liabilities, as follows:

                   (a) Unsecured Indebtedness (excluding the Obligations) which
is incurred under a revolving credit facility with a commercial bank, trust
company, or savings and loan association, PROVIDED that, in the event the
Borrower acquires a Real Estate Asset with respect to which there is any such
unsecured Indebtedness, the Borrower shall have a period of 90 days in which to
repay such Indebtedness in full;

                   (b) Indebtedness which would result in a Default or Event of
Default under Section 10,

                   (c) An aggregate amount in excess of $10,000,000 at any one
time in respect of taxes, assessments, governmental charges or levies and claims
for labor, materials and supplies (other than in respect of properties owned by
Partially-Owned Real Estate Holding Entities) for which payment therefor is
required to be made in accordance with the provisions of Section 8.9 and such
payment is due and delinquent and which is not being contested diligently and in
good faith;

                   (d) An aggregate amount in excess of $10,000,000 at any one
time in respect of uninsured judgments or awards, with respect to which the
applicable periods for taking appeals have expired, or with respect to which
final and unappealable judgments or awards have been rendered, and such
judgments or awards remain unpaid for more than thirty (30) days; and

                   (e) With respect to BPI only, any and all Liabilities other
than (i) the Liabilities existing as of the Closing Date of the kind or nature
described on SCHEDULE 9.1(E), (ii) Liabilities incurred by BPI in the ordinary
course of business and which are of the same or similar kind or nature to those
permitted under subclause (i) above, (iii) Liabilities incurred by BPI in
connection with its maintenance of corporate status, preparation of SEC filings,
accountants' fees and similar administrative matters, and (iv) other Liabilities
incurred by BPI of the same or similar kind or nature as currently exist,

                                      -78-
<Page>

so long as such Liabilities are not, individually or in the aggregate, material
to BPI, BPLP or, taken as a whole, the BP Group.

    The terms and provisions of this Section 9.1 are in addition to, and not in
limitation of, the covenants set forth in Section 10.

    Without limiting the foregoing, but subject to the other provisions of this
Agreement (including without limitation Section 10), Indebtedness Without
Recourse to any of the Credit Parties or any of their respective assets other
than their respective interests in the Real Estate Assets that are subject to
such Indebtedness Without Recourse is not restricted other than with respect to
BPI, as set forth in subclause (e) above.

    Section 9.2.   RESTRICTIONS ON LIENS, ETC. None of the Borrower, BPI and any
Wholly-owned Subsidiary will: (a) create or incur or suffer to be created or
incurred or to exist any lien, mortgage, pledge, attachment, security interest
or other rights of third parties of any kind upon any of the Borrowing Base
Properties, whether now owned or hereafter acquired (but only for so long as
they remain Borrowing Base Properties), or upon the income or profits therefrom;
(b) acquire, or agree or have an option to acquire, any property or assets upon
conditional sale or other title retention or purchase money security agreement,
device or arrangement in connection with the operation of the Borrowing Base
Properties; (c) suffer to exist for a period of more than thirty (30) days, with
respect to the Borrowing Base Properties, any taxes, assessments, governmental
charges and claims for labor, materials and supplies for which payment thereof
is not being contested or for which payment notwithstanding a contest is
required to be made in accordance with the provisions of Section 8.9 and has not
been timely made and, with respect to any individual Borrowing Base Property, is
in an amount in excess of the lesser of (i) $500,000 and (ii) three percent (3%)
of the fair market value of the applicable Borrowing Base Property; or (d) sell,
assign, pledge or otherwise transfer for security any accounts, contract rights,
general intangibles, chattel paper or instruments, with or without recourse,
relating to the Borrowing Base Properties (the foregoing items (a) through (d)
being sometimes referred to in this Section 9.2 collectively as "Liens"),
PROVIDED that the Borrower, BPI and any Wholly-owned Subsidiary may create or
incur or suffer to be created or incurred or to exist (but only, with respect to
BPI, as set forth in subclause (vi) below to the extent relating to the Real
Estate Asset located at 100 East Pratt Street, Baltimore, Maryland):

                   (i)    Liens securing taxes, assessments, governmental
charges or levies or claims for labor, material and supplies, the Indebtedness
with respect to which is not prohibited by Section 9.1(c) or Section 9.2(c);

                   (ii)   Liens arising out of deposits or pledges made in
connection with, or to secure payment of, worker's compensation, unemployment
insurance, old age pensions or other social security obligations; and deposits
with utility companies and other similar deposits made in the ordinary course of
business;

                                      -79-
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                   (iii)  Liens (other than affecting the Borrowing Base
Properties) in respect of judgments or awards, the Indebtedness with respect to
which is not prohibited by Section 9.1(d);

                   (iv)   encumbrances on properties consisting of easements,
rights of way, covenants, zoning and other land-use restrictions, building
restrictions, restrictions on the use of real property and defects and
irregularities in the title thereto; landlord's or lessor's Liens under Leases
to which the Borrower or any wholly-owned Subsidiary is a party or bound;
purchase options granted at a price not less than the market value of such
property; and other minor Liens or encumbrances on properties, none of which
interferes materially and adversely with the use of the property affected in the
ordinary conduct of the business of the Borrower, and which matters (x) do not
individually or in the aggregate have a material adverse effect on the business
of BPLP, BPI or, taken as a whole, the BP Group and (y) do not make title to
such property unmarketable by the conveyancing standards in effect where such
property is located;

                   (v)    any Leases;

                   (vi)   Liens and other encumbrances or rights of others which
exist on the date of this Agreement and which do not otherwise constitute a
breach of this Agreement, including, without limitation, Liens created by or
pursuant to the Organizational Documents of the Borrower with respect to a
restriction on sale or refinancing of a Real Estate Asset that would be an
acceptable Lien under the definition of "Unencumbered Asset", so long as all
such Liens, individually, or in the aggregate, do not have a material adverse
effect on BPLP, BPI or, taken as a whole, the BP Group; PROVIDED that nothing in
this clause (vi) shall be deemed or construed to permit an Borrowing Base
Property to be subject to a Lien to secure Indebtedness;

                   (vii)  as to Real Estate Assets which are acquired after the
date of this Agreement, Liens and other encumbrances or rights of others which
exist on the date of acquisition and which do not otherwise constitute a breach
of this Agreement; provided that nothing in this clause (vii) shall be deemed or
construed to permit a Borrowing Base Property to be subject to a Lien to secure
Indebtedness;

                   (viii) Liens affecting the Borrowing Base Properties in
respect of judgments or awards that are under appeal or have been in force for
less than the applicable period for taking an appeal, so long as execution is
not levied thereunder or in respect of which, at the time, a good faith appeal
or proceeding for review is being diligently prosecuted, and in respect of which
a stay of execution shall have been obtained pending such appeal or review;
PROVIDED that the Borrower shall have obtained a bond or insurance or made other
arrangements with respect thereto, in each case reasonably satisfactory to the
Agent;

                                      -80-
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                   (ix)   Liens securing Indebtedness for the purchase price of
capital assets (other than Real Estate Assets but including Indebtedness in
respect of Capitalized Leases for equipment and other equipment leases) to the
extent not otherwise prohibited by Section 9.1; and

                   (x)    other Liens (other than affecting the Borrowing Base
Properties) in connection with any Indebtedness permitted under Section 9.1.

                   Nothing contained in this Section 9.2 shall restrict or limit
the Borrower or any of their respective Wholly-owned Subsidiaries from creating
a Lien in connection with any Real Estate Asset which is not a Borrowing Base
Property and otherwise in compliance with the other terms of this Agreement.

                   BPI shall not create or incur or suffer to be created or
incurred any Lien on any of its directly-owned properties or assets, including,
in any event, its general partner interests and limited partner interests in the
Borrower.

    Section 9.3.   RESTRICTIONS ON INVESTMENTS. None of the Borrower, BPI, or
any of their respective Subsidiaries will make or permit to exist or to remain
outstanding any Investment except, with respect to the Borrower and its
Subsidiaries only, Investments in:

                   (a) marketable direct or guaranteed obligations of the United
States of America that mature within two (2) years from the date of purchase
(including investments in securities guaranteed by the United States of America
such as securities in so-called "overseas private investment corporations");

                   (b) demand deposits, certificates of deposit, bankers
acceptances and time deposits of United States banks having total assets in
excess of $1,000,000,000;

                   (c) securities commonly known as "commercial paper" issued by
a corporation organized and existing under the laws of the United States of
America or any state thereof that at the time of purchase have been rated and
the ratings for which are not less than "P 1" if rated by Moody's, and not less
than "A 1" if rated by S&P;

                   (d) Investments existing on the Closing Date and listed in
the SEC Filings or in the financial statements referred to in Section 7.4;

                   (e) other Investments hereafter in connection with the
acquisition and development of Permitted Properties by the Borrower or any
Wholly-owned Subsidiary of the Borrower, PROVIDED that the aggregate amounts
actually invested by Borrower (or if not invested directly by Borrower, actually
invested by an Affiliate of the Borrower for which the Borrower has any funding
obligation) and such Wholly-owned Subsidiary at any time as Development Costs in
Real Estate Assets Under Development (and without regard to any obligations of
the Borrower or such Subsidiary to provide funds which have

                                      -81-
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not yet been invested) will not exceed twenty-five percent (25%) of the Fair
Market Value of Real Estate Assets at the time of any such Investment;

                   (f) subject at all times to the restrictions of Section 9.7
hereof and subject to what is permitted in clause (e) above, so long as no Event
of Default has occurred and is continuing or would occur after giving effect
thereto, Investments (i) in Real Estate Assets, (ii) in interests in
Partially-Owned Real Estate Holding Entities, (iii) in the stock of or other
beneficial interests in Persons whose primary operations consist of the
ownership, development, operation or management of Real Estate Assets or the
ownership of Mortgages, or (iv) consisting of the acquisition of (A) contracts
for the management of real estate assets for third parties unrelated to the
Borrower, or (B) Mortgages, PROVIDED that the aggregate fair market value of
Borrower's and any such Subsidiary's interest in such other businesses
(excluding management and development businesses except to the extent of amounts
actually invested by the Borrower or any such Subsidiary therein) does not
exceed twenty-five percent (25%) of the Consolidated Total Adjusted Asset Value
at the time of any such Investment;

                   (g) any Investments now or hereafter made in any Wholly-owned
Subsidiary;

                   (h) Investments in respect of (1) equipment, inventory and
other tangible personal property acquired in the ordinary course of business,
(2) current trade and customer accounts receivable for services rendered in the
ordinary course of business and payable in accordance with customary trade
terms, (3) advances in the ordinary course of business to employees for travel
expenses, drawing accounts and similar expenditures, (4) prepaid expenses made
in the ordinary course of business;

                   (i) shares of so-called "money market funds" registered with
the SEC under the Investment Company Act of 1940 which maintain a level
per-share value, invest principally in marketable direct or guaranteed
obligations of the United States of America and agencies and instrumentalities
thereof, and have total assets in excess of $50,000,000;

                   (j) Investments made by the Borrower in businesses which are
not in the business of commercial real estate so long as such businesses have
real estate related purposes or such Investment is in connection with a real
estate related transaction, PROVIDED that the aggregate amounts actually
invested by the Borrower in such businesses shall not exceed two percent (2%) of
the Consolidated Total Adjusted Asset Value at the time of each such Investment.
Without limitation of the provisions of the foregoing sentence, the Banks
retroactively increase the amount of the waiver of the restrictions on
Investments set forth in Section 9.3 which is contained in the August 23, 1999
waiver letter in favor of the Borrower by $1,500,000; and

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                   (k) Investments made by the Borrower in Real Estate Assets
constituting multi-family, retail and parking properties, PROVIDED that the
aggregate amounts actually invested by the Borrower in such businesses which are
not ancillary or related to Permitted Properties, shall not exceed five percent
(5%) of the Consolidated Total Adjusted Asset Value at the time of each such
Investment.

    Notwithstanding the foregoing, BPI shall be permitted to make and maintain
(i) Investments in the Borrower, (ii) Investments in the Borrower's Subsidiaries
(including, without limitation, in Boston Properties LLC), PROVIDED that BPI's
percentage equity interest in any such Subsidiary shall not exceed 1%, (iii)
Investments which exist as of the date of this Agreement and are set forth on
SCHEDULE 9.3, and (iv) other Investments which would be permitted by the terms
of this Agreement, including Section 8.7 above. The Borrower shall cause BPI to
contribute to the Borrower, promptly upon, and in any event within 3 Business
Days of, BPI's receipt thereof, 100% of the aggregate proceeds received by BPI
in connection with any offering of stock or debt in BPI (net of fees and
expenses customarily incurred in such offerings).

    Section 9.4.   MERGER, CONSOLIDATION AND DISPOSITION OF ASSETS; ASSETS OF
BPI.

    None of the Borrower, BPI or any of their respective Subsidiaries will:

                   (a) become a party to any merger or consolidation without
prior written approval of the Majority Banks, except that so long as no Default
or Event of Default has occurred and is continuing, or would occur after giving
effect thereto, the merger or consolidation of one or more Persons with and into
the Borrower or BPI shall be permitted in connection with the acquisition of
Real Estate Assets if the Borrower or BPI, as the case may be, is the surviving
entity; PROVIDED that (i) if any such merger or consolidation involves BPI, the
assets acquired (including any equity interests) are, promptly after the
consummation of the acquisition, contributed to the Borrower or one of its
Subsidiaries and all liabilities assumed by BPI in connection with the
acquisition are assumed by the Borrower or such Subsidiary, and (ii) prior to
any such merger or consolidation (other than (x) the merger or consolidation of
one or more Wholly-owned Subsidiaries with and into the Borrower or (y) the
merger or consolidation of two or more Wholly owned Subsidiaries of the
Borrower), the Borrower shall provide to the Agent (with copies to the Agent for
each Bank) a statement in the form of EXHIBIT C-4 hereto signed by the chief
financial officer or treasurer of the Borrower and setting forth in reasonable
detail computations evidencing compliance with the covenants contained in
Section Section 10.1 through 10.7 and certifying, to the best knowledge of the
signatory, that no Default or Event of Default has occurred and is continuing,
or would occur and be continuing after giving effect to such merger or
consolidation and all liabilities, fixed or contingent, pursuant thereto; or

                   (b) without limitation of the other provisions of this
Agreement, and in particular, subject to the provisions of Section 14 relating
to the removal of a

                                      -83-
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Real Estate Asset from the Borrowing Base in connection with the curing of any
Default, Event of Default or Non-Material Breach, sell, transfer or otherwise
dispose of any Real Estate Assets or grant a Lien to secure Indebtedness
otherwise permitted hereunder unless no Default or Event of Default would exist
or occur and be continuing after giving effect to any such transaction.

    Section 9.5.   COMPLIANCE WITH ENVIRONMENTAL LAWS. None of the Borrower, BPI
or any Subsidiary will do any of the following: (a) use any of the Real Estate
Assets or any portion thereof as a facility for the handling, processing,
storage or disposal of Hazardous Substances except for quantities of Hazardous
Substances used in the ordinary course of business and in compliance with all
applicable Environmental Laws, (b) cause or permit to be located on any of the
Real Estate Assets any underground tank or other underground storage receptacle
for Hazardous Substances except in compliance with Environmental Laws, (c)
generate any Hazardous Substances on any of the Real Estate Assets except in
compliance with Environmental Laws, or (d) conduct any activity at any Real
Estate Asset or use any Real Estate Asset in any manner so as to cause a Release
in violation of applicable Environmental Laws; unless, with respect to clause
(d) above, any such occurrence would constitute a Non-Material Breach hereunder.

    Section 9.6.   DISTRIBUTIONS.

                   (a) The Borrower will not make (i) annual Distributions in
excess of 90% of "funds from operations"; (ii) Distributions in excess of 100%
of "funds from operations" for more than three consecutive fiscal quarters; or
(iii) any Distributions during any period after any monetary Event of Default
has occurred; PROVIDED, HOWEVER, (a) that the Borrower may at all times
(including while a monetary Event of Default is continuing) make Distributions
to the extent (after taking into account all available funds of BPI from all
other sources) required in order to enable BPI to continue to qualify as a REIT
and (b) in the event that the Borrower cures any such monetary default in clause
(iii) above and the Agent has accepted such cure prior to accelerating the Loan,
the limitation of clause (iii) above shall cease to apply with respect to such
monetary default. The Agent and the Banks acknowledge that, because
extraordinary gains are not included in "funds from operations", the
restrictions on Distributions do not restrict Distributions of extraordinary
gains, and such Distributions of extraordinary gains shall not be included in
the calculation of the percentages set forth above.

                   (b) BPI will not, during any period when any monetary Event
of Default has occurred and is continuing, make any Distributions in excess of
the Distributions required to be made by BPI in order to maintain its status as
a REIT.

    Section 9.7.   HOTEL PROPERTIES. At any time of determination, the hotel
properties shall not constitute more than 25% of the Consolidated Total Adjusted
Asset Value or more than 25% of the number of Real Estate Assets. The Agent
acknowledges that, on the Closing Date, there are one hundred forty two (142)
Real Estate Assets.

                                      -84-
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    Section 10.    FINANCIAL COVENANTS; COVENANTS REGARDING BORROWING BASE
PROPERTIES. The Borrower covenants and agrees that, so long as any Loan, Letter
of Credit or Note is outstanding or any Bank has any obligation to make any Loan
or any Bank has any obligation to issue, extend or renew any Letters of Credit:

    Section 10.1.  CONSOLIDATED TOTAL INDEBTEDNESS. As at the end of any fiscal
quarter, Consolidated Total Indebtedness on the last day of such quarter shall
not exceed 60% of Consolidated Total Adjusted Asset Value on the last day of
such quarter, PROVIDED that (i) for a single period of not more than five
consecutive fiscal quarters of the Borrower, Consolidated Total Indebtedness on
the last day of a fiscal quarter may exceed 60% of Consolidated Total Adjusted
Asset Value on the last day of such quarter (but in no event may it exceed 65%
of Consolidated Total Adjusted Asset Value), and (ii) in no event may such five
consecutive fiscal quarters include the fiscal quarter in which the Maturity
Date occurs or the fiscal quarter immediately preceding the fiscal quarter in
which the Maturity Date occurs. Such single five consecutive fiscal quarter
period shall commence with the first fiscal quarter for which the financial
statements pertaining to such quarter evidence Consolidated Total Indebtedness
in excess of 60% of Consolidated Total Adjusted Asset Value on the last day of
such quarter, and shall not be available to the Borrower again, whether or not
the Borrower utilized all five consecutive fiscal quarters.

    Section 10.2.  SECURED CONSOLIDATED TOTAL INDEBTEDNESS. As at the end of any
fiscal quarter, Secured Consolidated Total Indebtedness shall not exceed 55% of
Consolidated Total Adjusted Asset Value on the last day of such quarter.

    Section 10.3.  DEBT SERVICE COVERAGE. As at the end of any fiscal quarter,

                   (A)  the ratio of (i) Consolidated EBITDA for such quarter to
                        (ii) Consolidated Fixed Charges for such quarter
                        (inclusive of any Consolidated Fixed Charges
                        attributable to dividends and distributions (excluding
                        distributions on account of extraordinary gains) paid or
                        required to be paid in such quarter on the Preferred
                        Creditor Equity) shall not be less than 1.50 to 1.0; and

                   (B)  the ratio of (i) Consolidated EBITDA for such quarter to
                        (ii) Consolidated Fixed Charges for such quarter
                        (inclusive of any Consolidated Fixed Charges
                        attributable to dividends and distributions (excluding
                        distributions on account of extraordinary gains) paid or
                        required to be paid in such quarter on the Preferred
                        Equity) shall not be less than 1.30 to 1.0.

    Section 10.4.  [Reserved.]

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    Section 10.5.  NET WORTH. As at the end of any fiscal quarter or any other
date of measurement, the Consolidated Net Worth of the Borrower and its
Subsidiaries shall not be less than the sum of (i) $2,000,000,000 plus (ii) 75%
of the aggregate proceeds received by BPI (net of fees and expenses customarily
incurred in transactions of such type) in connection with any offering of stock
in BPI, PLUS (iii) 75% of the aggregate value of operating units issued by the
Borrower in connection with asset or stock acquisitions (valued at the time of
issuance by reference to the terms of the agreement pursuant to which such units
are issued), in each case after the Closing Date and on or prior to the date
such determination of Consolidated Net Worth is made.

    Section 10.6.  BORROWING BASE PROPERTIES.

                   (a) As at the end of any fiscal quarter or any other date of
measurement, the Borrower shall not permit Unsecured Consolidated Total
Indebtedness (exclusive of Accounts Payable, but including amounts outstanding
under any Loans and the aggregate undrawn face amount of all outstanding Letters
of Credit after giving effect to Loan Requests) to equal or exceed 60% of the
aggregate Borrowing Base Value, PROVIDED that in the event that Consolidated
Total Indebtedness exceeds 60% of Consolidated Total Adjusted Asset Value at any
time, the Borrower shall not permit the Unsecured Consolidated Total
Indebtedness (exclusive of Accounts Payable, but including the outstanding
principal amount of all Loans and the aggregate undrawn face amount of all
outstanding Letters of Credit after giving effect to Loan Requests) to equal or
exceed 55% of the aggregate Borrowing Base Value.

                   (b) No more than 20% of the Borrowing Base Value shall be
derived from any single Borrowing Base Property, PROVIDED that from the Closing
Date through June 30, 2004, 399 Park Avenue (to the extent that it otherwise
qualifies as a Borrowing Base Property) may constitute up to 48% of the
Borrowing Base Value. On July 1, 2004, or if earlier, on the date that 399 Park
Avenue constitutes less than 35% of the Borrowing Base Value, then two (2)
Borrowing Base Properties may constitute up to 55% of the Borrowing Base Value
and such two (2) Borrowing Base Properties (and no others) may exceed the 20%
individual Borrowing Base Property limit referred to above. To evidence
compliance with the foregoing, the Borrower shall submit to the Agent a
compliance certificate in the form of EXHIBIT C-5.

                   (c) For purposes of determining the Borrowing Base Value, the
Net Operating Income of any Borrowing Base Property acquired during such prior
fiscal quarter shall be adjusted on a pro-forma basis by projecting the Net
Operating Income generated by each such acquired Borrowing Base Property for the
portion of the quarter during which it was owned or ground-leased by the
Borrower over the entire quarter.

                   (d) Notwithstanding the Borrowing Base Conditions, in the
event that the Borrower desires to include any Unencumbered Asset in the
Borrowing Base that does not meet one or more of the Borrowing Base Conditions,
any such Unencumbered

                                      -86-
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Asset shall only be permitted to be included in the Borrowing Base in the event
that (i) the Borrower has submitted to the Agent a compliance certificate in the
form of EXHIBIT C-5, modified to reflect the non-conformity of the proposed
Borrowing Base Property, and (ii) the Majority Banks have provided the Borrower
with written approval, in their sole discretion, for such non-conforming
Unencumbered Asset to be included in the Borrowing Base. Upon any such written
approval by the Majority Banks, such Unencumbered Asset shall be considered a
Borrowing Base Property for all purposes hereunder, PROVIDED that on the date of
inclusion of any such Unencumbered Asset in the Borrowing Base (and thereafter
in accordance with the terms of this Agreement), such Unencumbered Asset is
otherwise in compliance with the Borrowing Base Conditions other than with
respect to the non-conformity as certified by the Borrower and approved by the
Majority Banks in the compliance certificate submitted by the Borrower under
clause (i) of the preceding sentence, and PROVIDED, FURTHER that there is
otherwise no Default or Event of Default existing upon the date of, or arising
as a result of, the inclusion of such Unencumbered Asset in the Borrowing Base.

    (e)            The Borrowing Base must at all times be comprised of at least
fifteen (15) Real Estate Assets.

    Section 10.7.  BORROWING BASE DEBT SERVICE COVERAGE RATIO. As of the end of
any fiscal quarter or any other date of measurement, the Borrowing Base Debt
Service Coverage Ratio shall not be less than 1.40 to 1.0.

    Section 11.    [Reserved.]

    Section 12.    CONDITIONS TO THE FIRST ADVANCE. The obligations of any Bank
to make the initial Revolving Credit Loans and of the Fronting Bank to issue any
initial Letters of Credit (and to maintain the existing outstanding Loans and
Letters of Credit) shall be subject to the satisfaction of the following
conditions precedent on or prior to the Closing Date:

    Section 12.1.  LOAN DOCUMENTS. Each of the Loan Documents shall have been
duly executed and delivered by the respective parties thereto and shall be in
full force and effect.

    Section 12.2.  CERTIFIED COPIES OF ORGANIZATION DOCUMENTS. The Agent shall
have received (i) from the Borrower a copy, certified as of a recent date by a
duly authorized officer of BPI, in its capacity as general partner of the
Borrower, to be true and complete, of the Agreement of Limited Partnership of
BPLP and any other Organizational Document or other agreement governing the
rights of the partners or other equity owners of the Borrower, and (ii) from BPI
a copy, certified as of a recent date by the appropriate officer of the State of
Delaware to be true and correct, of the corporate charter of BPI, in each case
along with any other organization documents of the Borrower or BPI and their

                                      -87-
<Page>

respective general partners, as the case may be, and each as in effect on the
date of such certification.

    Section 12.3.  BY-LAWS; RESOLUTIONS. All action on the part of the Borrower
and BPI necessary for the valid execution, delivery and performance by the
Borrower and BPI of this Agreement and the other Loan Documents to which any of
them is or is to become a party shall have been duly and effectively taken, and
evidence thereof satisfactory to the Banks shall have been provided to the
Agent. The Agent shall have received from BPI true copies of its by-laws and the
resolutions adopted by its board of directors authorizing the transactions
described herein and evidencing the due authorization, execution and delivery of
the Loan Documents to which BPI and/or the Borrower is a party, each certified
by the secretary as of a recent date to be true and complete.

    Section 12.4.  INCUMBENCY CERTIFICATE: AUTHORIZED SIGNERS. The Agent shall
have received from BPI an incumbency certificate, dated as of the Closing Date,
signed by a duly authorized officer of BPI and giving the name of each
individual who shall be authorized: (a) to sign, in the name and on behalf of
the Borrower and BPI, as the case may be, each of the Loan Documents to which
the Borrower or BPI is or is to become a party; (b) to make Loan and Conversion
Requests on behalf of the Borrower and (c) to give notices and to take other
action on behalf of the Borrower or BPI as applicable, under the Loan Documents.

    Section 12.5.  TITLE POLICIES. The Agent (on behalf of the Banks) shall have
received copies of the owner's title policies, if any, for all Borrowing Base
Properties for which the Agent has requested copies, and shall have been
permitted to review such other title policies at BPLP as it has requested prior
to the Closing Date.

    Section 12.6.  CERTIFICATES OF INSURANCE. The Agent shall have received, to
the extent available (and if not available on the Closing Date, within thirty
(30) days after the Closing Date) (a) current certificates of insurance as to
all of the insurance maintained by Borrower on the Borrowing Base Properties
(including flood insurance if necessary) from the insurer or an independent
insurance broker, identifying insurers, types of insurance, insurance limits,
and policy terms; and (b) such further information and certificates from
Borrower, its insurers and insurance brokers as the Agent may reasonably
request.

    Section 12.7.  HAZARDOUS SUBSTANCE ASSESSMENTS. To the extent requested by
the Agent, the Agent shall have received hazardous waste site assessment reports
running in favor of the Agent and the Banks concerning Hazardous Substances (or
the threat thereof) and asbestos with respect to the Borrowing Base Properties,
dated no earlier than July 31, 1996, from environmental engineers reasonably
acceptable to the Agent, such reports to be in form and substance satisfactory
to the Agent and each of the Banks.

    Section 12.8.  OPINION OF COUNSEL CONCERNING ORGANIZATION AND LOAN
DOCUMENTS. Each of the Banks and the Agent shall have received favorable
opinions addressed to the Banks

                                      -88-
<Page>

and the Agent in form and substance reasonably satisfactory to the Banks and the
Agent from Goodwin Procter LLP and state specific local counsel who are
reasonably satisfactory to Agent, each as counsel to the Borrower, BPI and their
respective Subsidiaries, with respect to applicable law, including, without
limitation, Massachusetts law and certain matters of Delaware law.

    Section 12.9.  [Reserved.]

    Section 12.10. STRUCTURAL CONDITION ASSURANCES. To the extent requested by
the Agent, the Agent and each of the Banks shall have received evidence
satisfactory to the Agent and each of the Banks as to the good physical
condition of the Buildings and that utilities and public water and sewer service
is available at the lot lines of the Borrowing Base Properties and connected
directly to the Buildings on the Borrowing Base Properties with all necessary
Permits.

    Section 12.11. FINANCIAL ANALYSIS OF BORROWING BASE PROPERTIES. Each of the
Banks shall have completed, to its satisfaction, a financial analysis of each
Borrowing Base Property, which analysis shall include, without limitation, a
review, with respect to each Borrowing Base Property, of (i) the most recent
rent rolls, (ii) three (3) year historical and projected operating statements,
(iii) cash flow projections, (iv) market data, (v) selected Leases, and (vi)
tenant financial statements, to the extent available. The costs and expenses
incurred by each Bank (other than the Agent) in conducting such analysis shall
be borne by such Bank; PROVIDED that the Borrower will furnish such materials to
the Banks at the Borrower's expense. The Borrower agrees that at the request of
any Bank it will furnish the materials described in this Section 12.11 to such
Bank after the Closing Date.

    Section 12.12. INSPECTION OF BORROWING BASE PROPERTIES. At the Agent's
election, the Agent shall have completed to its satisfaction, and at the
Borrower's expense, an inspection of the Borrowing Base Properties which the
Agent has not inspected in the one (1) year period prior to the Closing Date.

    Section 12.13. CERTIFICATIONS FROM GOVERNMENT OFFICIALS. The Agent shall
have received long-form certifications from government officials evidencing the
legal existence, good standing and foreign qualification of the Borrower and
BPI, along with a certified copy of the certificate of limited partnership of
the Borrower, all as of the most recent practicable date.

    Section 12.14. [Reserved.]

    Section 12.15. PROCEEDINGS AND DOCUMENTS. All proceedings in connection with
the transactions contemplated by this Agreement, the other Loan Documents and
all other documents incident thereto shall be satisfactory in form and substance
to each of the Banks and to the Agent's counsel, and the Agent, each of the
Banks and such counsel

                                      -89-
<Page>

shall have received all information and such counterpart originals or certified
or other copies of such documents as the Agent may reasonably request.

    Section 12.16. FEES. The Borrower shall have paid to the Agent, for the
accounts of the Banks or for its own account, as applicable, all of the fees and
expenses that are due and payable as of the Closing Date in accordance with this
Agreement and with any fee letter of even date herewith between the Borrower and
the Agent.

    Section 12.17. CLOSING CERTIFICATE; COMPLIANCE CERTIFICATE. The Borrower
shall have delivered a Closing Certificate to the Agent, the form of which is
attached hereto as EXHIBIT E. The Borrower shall have delivered a compliance
certificate in the form of EXHIBIT C-7 hereto evidencing compliance with the
covenants set forth in Section 10 on a PRO FORMA basis.

    Section 12.18. PARTNERSHIP DOCUMENTS. The Agent shall have received from the
Borrower true copies of all Partnership Documents.

    Section 12.19. RELEASE DOCUMENTS. The Agent shall have delivered to the
Borrower appropriate release documentation necessary to release all, if any,
security interests granted by the Borrower in the Borrowing Base Properties,
including, without limitation, appropriate releases of mortgages and deeds of
trust and UCC termination statements.

    Section 13.    CONDITIONS TO ALL BORROWINGS. The obligations of any Bank to
make any Loan and of any Bank to issue, extend or renew any Letter of Credit, in
each case, whether on or after the Closing Date, shall also be subject to the
satisfaction of the following conditions precedent:

    Section 13.1.  REPRESENTATIONS TRUE; NO EVENT OF DEFAULT; COMPLIANCE
CERTIFICATE. Each of the representations and warranties made by or on behalf of
the Borrower, BPI or any of their respective Subsidiaries contained in this
Agreement, the other Loan Documents or in any document or instrument delivered
pursuant to or in connection with this Agreement shall be true as of the date as
of which they were made and shall also be true at and as of the time of the
making of each Loan or the issuance, extension or renewal of each Letter of
Credit, with the same effect as if made at and as of that time (except (i) to
the extent of changes resulting from transactions contemplated or not prohibited
by this Agreement or the other Loan Documents (including, without limitation,
the fact that a Real Estate Asset may cease to be a Borrowing Base Property
pursuant to the terms of this Agreement) and changes occurring in the ordinary
course of business, (ii) to the extent that such representations and warranties
relate expressly to an earlier date and (iii) to the extent otherwise
represented by the Borrower with respect to the representation set forth in
Section 7.10); and no Default or Event of Default under this Agreement shall
have occurred and be continuing on the date of any Loan Request or on the
Drawdown Date of any Loan. Each of the Banks shall have received a certificate
of the Borrower signed by an authorized officer of the Borrower as provided in
Section 2.4(iv)(c).

                                      -90-
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    Section 13.2.  NO LEGAL IMPEDIMENT. No change shall have occurred any law or
regulations thereunder or interpretations thereof that in the reasonable
opinion, as determined in good faith, of the Agent or any Bank would make it
illegal for any Bank to make such Loan or to participate in the issuance,
extension or renewal of such Letter of Credit or, in the reasonable opinion, as
determined in good faith, of the Agent, would make it illegal to issue, extend
or renew such Loan or Letter of Credit.

    Section 13.3.  GOVERNMENTAL REGULATION. Each Bank shall have received such
statements in substance and form reasonably satisfactory to such Bank as such
Bank shall reasonably require in good faith for the purpose of compliance with
any applicable regulations of the Comptroller of the Currency or the Board of
Governors of the Federal Reserve System.

    Section 14.    EVENTS OF DEFAULT; ACCELERATION; ETC..

    Section 14.1.  EVENTS OF DEFAULT AND ACCELERATION. If any of the following
events ("Events of Default") shall occur:

                   (a) the Borrower shall fail to pay any principal of the Loans
when the same shall become due and payable;

                   (b) the Borrower shall fail to pay any interest on the Loans
or any other sums due hereunder or under any of the other Loan Documents
(including, without limitation, amounts due under Section 8.17) when the same
shall become due and payable, and such failure continues for three (3) days
(PROVIDED that in the case of such sums due other than for interest, the
Borrower shall have received from the Agent notice of the nature and amount of
such other amounts and that payment therefor is due);

                   (c) the Borrower, BPI or any of their respective Subsidiaries
shall fail to comply, or to cause BPI to comply, as the case may be, with any of
the respective covenants contained in the following:

                            (i)    Section 8.1 (except with respect to
                       principal, interest and other sums covered by clauses (a)
                       or (b) above);

                            (ii)   Section 8.5 (clauses (a) through (d)), unless
                       such failure is cured within fifteen (15) Business Days;

                            (iii)  Section 8.6 (as to the legal existence of
                       Borrower), unless such breach relates to a Borrower other
                       than BPLP and is a Non-Material Breach and Section 8.6
                       (as it relates to BPI);

                            (iv)   Section 8.7 (as to the legal existence and
                       REIT status of BPI or as it otherwise relates to BPI);

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                            (v)    Section 8.10, unless such failure is cured
                       within three (3) Business Days;

                            (vi)   Section 8.12;

                            (vii)  Section 8.13;

                            (viii) Section 8.14, unless, with respect solely to
                       the last sentence of clause (a) of Section 8.14, such
                       failure is cured within thirty (30) days;

                            (ix)   Section 8.16;

                            (x)    Section 9.1;

                            (xi)   Section 9.2 (pertaining to liens, mortgages,
                       pledges, attachments or other security interests with
                       respect to Borrowing Base Properties) unless (1) with
                       respect solely to such liens or attachments which are not
                       affirmatively created or incurred, such failure is cured
                       within thirty (30) days (with no double-counting of any
                       cure period set forth in Section 9.2) or (2) such failure
                       is a breach which is a Non-Material Breach or Section 9.2
                       (pertaining to BPI);

                            (xii)  Section 9.3;

                            (xiii) Section 9.4;

                            (xiv)  Section 9.6;

                            (xv)   Section 9.7; and

                            (xvi)  Section 10;

                   (d) the Borrower, BPI or any of their respective Subsidiaries
shall fail to perform, or to cause BPI to perform, any other term, covenant or
agreement contained herein or in any of the other Loan Documents (other than
those specified elsewhere in this Section 14) and such failure continues for
thirty (30) days after written notice of such failure from the Agent (such
notice not, however, being required for any failure with respect to which the
Borrower is otherwise obligated hereunder to notify the Agent or the Banks),
PROVIDED, HOWEVER, that if the Borrower is diligently and in good faith
prosecuting a cure of any such failure or breach that is capable of being cured
(all as determined by the Agent in its reasonable and good faith judgment), the
Borrower shall be permitted an

                                      -92-
<Page>

additional thirty (30) days (but in no event more than an aggregate of sixty
(60) days after any such initial written notice from the Agent) to effect such
cure;

                   (e) any representation or warranty made by or on behalf of
the Borrower, BPI or any of their respective Subsidiaries in this Agreement or
any of the other Loan Documents shall prove to have been false in any material
respect upon the date when made or deemed to have been made or repeated and the
same is not otherwise specified herein to be a Non-Material Breach;

                   (f) the Borrower or any of its Subsidiaries or, to the extent
of Recourse to the Borrower or such Subsidiaries thereunder, any of their
respective Affiliates, shall fail to pay at maturity, or within any applicable
period of grace, any obligation for borrowed money or credit received or in
respect of any Capitalized Leases (other than non-recourse obligations or
credit), which is in excess of $50,000,000, either individually or in the
aggregate, or fail to observe or perform any material term, covenant, condition
or agreement contained in any agreement, document or instrument by which it is
bound evidencing, securing or otherwise relating to such Recourse obligations,
evidencing or securing borrowed money or credit received or in respect of any
Capitalized Leases for such period of time (after the giving of appropriate
notice if required) as would permit the holder or holders thereof or of any
obligations issued thereunder in excess of $50,000,000, either individually or
in the aggregate, to accelerate the maturity thereof; PROVIDED, HOWEVER that
notwithstanding the foregoing, (i) no Event of Default shall occur pursuant to
this subparagraph (f) unless and until the holder or holders of such Recourse
Indebtedness have declared an event of default beyond any applicable notice and
grace periods, if any, on in excess of $50,000,000 of such Recourse Indebtedness
either individually or in the aggregate, and (ii) with respect solely to any
such Recourse Indebtedness of a Subsidiary or Affiliate of the Borrower (not
including any such Indebtedness which is Recourse to the Borrower), no Event of
Default shall occur pursuant to this subparagraph (f) if, upon the occurrence of
such event, the Borrower, promptly after obtaining knowledge of the same,
notifies the Agent in writing (with copies to the Agent for each Bank) of such
event and includes with such notice a Compliance Certificate in the form of
Exhibit C-6 evidencing to the satisfaction of the Agent that, as of the date
thereof, the Borrower is in compliance with all of the covenants set forth in
Section 10 after excluding such Subsidiary or Affiliate, and any Real Estate
Asset owned by such Subsidiary or Affiliate, from the calculation of such
covenants;

                   (g) any of BPLP, BPI or any of their respective Subsidiaries
shall make an assignment for the benefit of creditors, or admit in writing its
inability to pay or generally fail to pay its debts as they mature or become
due, or shall petition or apply for the appointment of a trustee or other
custodian, liquidator or receiver of any of BPLP, BPI or any of their respective
Subsidiaries or of any substantial part of the properties or assets of any of
such parties or shall commence any case or other proceeding relating to any of
the BPLP, BPI or any of their respective Subsidiaries under any bankruptcy,
reorganization, arrangement, insolvency, readjustment of debt, dissolution or
liquidation

                                      -93-
<Page>

or similar law of any jurisdiction, now or hereafter in effect, or shall take
any action to authorize or in furtherance of any of the foregoing, or if any
such petition or application shall be filed or any such case or other proceeding
shall be commenced against any of BPLP, BPI or any of their respective
Subsidiaries and (i) any of BPLP, BPI or any of their respective Subsidiaries
shall indicate its approval thereof, consent thereto or acquiescence therein or
(ii) any such petition, application, case or other proceeding shall continue
undismissed, or unstayed and in effect, for a period of ninety (90) days,
except, with respect solely to such parties other than BPLP and BPI, any of the
foregoing constitutes a Non-Material Breach;

                   (h) a decree or order is entered appointing any trustee,
custodian, liquidator or receiver or adjudicating any of BPLP, BPI or any of
their respective Subsidiaries bankrupt or insolvent, or approving a petition in
any such case or other proceeding, or a decree or order for relief is entered in
respect of any of BPLP, BPI or any of their respective Subsidiaries in an
involuntary case under federal bankruptcy laws as now or hereafter constituted,
except, with respect solely to such parties other than BPLP and BPI, any of the
foregoing constitutes a Non-Material Breach;

                   (i) there shall remain in force, undischarged, unsatisfied
and unstayed, for more than thirty (30) days, whether or not consecutive, any
uninsured final judgment against any of BPLP, BPI or any of their respective
Subsidiaries that, with other outstanding uninsured final judgments,
undischarged, unsatisfied and unstayed, against any of such parties exceeds in
the aggregate $10,000,000, except, with respect solely to such parties other
than BPLP and BPI, any of the foregoing constitutes a Non-Material Breach;

                   (j) any of the Loan Documents or any material provision of
any Loan Document shall be canceled, terminated, revoked or rescinded otherwise
than in accordance with the terms thereof or with the express prior written
agreement, consent or approval of the Agent, or any action at law, suit or in
equity or other legal proceeding to make unenforceable, cancel, revoke or
rescind any of the Loan Documents shall be commenced by or on behalf of the
Borrower or any of its Subsidiaries or BPI or any of its Subsidiaries, or any
court or any other governmental or regulatory authority or agency of competent
jurisdiction shall make a determination that, or issue a judgment, order, decree
or ruling to the effect that, any one or more of the Loan Documents is illegal,
invalid or unenforceable as to any material terms thereof;

                   (k) any "Event of Default" or default (after notice and
expiration of any period of grace, to the extent provided, as defined or
provided in any of the other Loan Documents, shall occur and be continuing;

                   (l) with respect to any Guaranteed Pension Plan, an ERISA
Reportable Event shall have occurred and the Majority Banks shall have
determined in their reasonable discretion that such event reasonably could be
expected to result in

                                      -94-
<Page>

liability of the Borrower or any of its Subsidiaries or BPI or any of its
Subsidiaries to the PBGC or such Guaranteed Pension Plan in an aggregate amount
exceeding $10,000,000 and such event in the circumstances occurring reasonably
could constitute grounds for the termination of such Guaranteed Pension Plan by
the PBGC or for the appointment by the appropriate United States District Court
of a trustee to administer such Guaranteed Pension Plan; or a trustee shall have
been appointed by the United States District Court to administer such Plan; or
the PBGC shall have instituted proceedings to terminate such Guaranteed Pension
Plan;

                   (m) subject to the Borrower's right to remove Real Estate
Assets from the Borrowing Base in accordance with the provisions set forth below
in this Section 14, the failure of any of the Real Estate Assets being included
from time to time as Borrowing Base Properties to comply with any of the
conditions set forth in the definition of Borrowing Base Properties; or

                   (n) without limitation of the other provisions of this
Section 14.1, BPI shall at any time fail to be the sole general partner of BPLP
or shall at any time be in contravention of any of the requirements contained in
Section 9.1(e) hereof, the last paragraph of Section 9.2 hereof, or Section 9.3
(including, without limitation, the last paragraph of Section 9.3);

                   then, and in any such event, so long as the same may be
continuing, the Agent may, and upon the request of the Majority Banks shall, by
notice in writing to the Borrower, declare all amounts owing with respect to
this Agreement, the Notes and the other Loan Documents and all Reimbursement
Obligations to be, and they shall thereupon forthwith become, immediately due
and payable without presentment, demand, protest or other notice of any kind,
all of which are hereby expressly waived by the Borrower, BPI and each of their
respective Subsidiaries; PROVIDED that in the event of any Event of Default
specified in Section 14.1(g) or 14.1(h), all such amounts shall become
immediately due and payable automatically and without any requirement of notice
from any of the Banks or the Agent or action by the Banks or the Agent.

                   For purposes of this Section 14, the term "Non-Material
Breach" shall refer to a breach of any representation, warranty or covenant
contained in this Agreement to which the term "Non-Material Breach" is expressly
applied herein, but only to the extent such breach does not (A) materially
adversely affect the business, properties or financial condition of BPLP, BPI
or, taken as a whole, the BP Group or (B) adversely affect the ability of BPLP,
BPI or, taken as a whole, the BP Group, to fulfill the Obligations to the Banks
and the Agent (including, without limitation, to repay all amounts outstanding
on the Loans, together with interest and charges thereon when due).

                   Notwithstanding the foregoing provisions of this Section 14.1
and in addition to the provisions set forth in the immediately preceding
paragraph, in the event of a Default, Event of Default or Non-Material Breach
arising as a result of the inclusion of any Real Estate Asset in the Borrowing
Base at any particular time of reference, if such Default,

                                      -95-
<Page>

Event of Default or Non-Material Breach is capable of being cured by the
exclusion of such Real Estate Asset from the Borrowing Base and from all other
covenant calculations under Section 10 or otherwise, the Borrower shall be
permitted a period not to exceed ten (10) days to submit to the Agent (with
copies to the Agent for each Bank) a compliance certificate in the form of
EXHIBIT C-4 hereto evidencing compliance with Section 2.1 and with all of the
covenants set forth in Section 10 (with calculations evidencing such compliance
after excluding from Borrowing Base Net Operating Income all of the Net
Operating Income generated by the Real Estate Asset to be excluded from the
Borrowing Base) and with the Borrowing Base Conditions, and otherwise certifying
that, after giving effect to the exclusion of such Real Estate Asset from the
Borrowing Base, no Default, Event of Default or Non-Material Breach will be
continuing.

    Section 14.2.  TERMINATION OF COMMITMENTS. If any one or more Events of
Default specified in Section 14.1(g) or Section 14.1(h) shall occur, any unused
portion of the Commitments or other commitments to extend credit hereunder shall
forthwith terminate and the Banks shall be relieved of all obligations to make
Loans to the Borrower and the Agent and any Fronting Bank shall be relieved of
all further obligations to issue, extend or renew Letters of Credit. If any
other Event of Default shall have occurred and be continuing, whether or not the
Banks shall have accelerated the maturity of the Loans pursuant to Section 14.1,
any Bank may, by notice to the Borrower, terminate the unused portion of that
Bank's Commitment or other commitment to extend credit hereunder, and upon such
notice being given such unused portion of such Commitment or other commitment
shall terminate immediately, such Bank shall be relieved of all further
obligations to make Loans, the Agent and any Fronting Bank shall be relieved of
all further obligations to issue, extend or renew Letters of Credit and the
Total Commitments shall be reduced accordingly. No such termination of a
Commitment or other commitment to extend credit hereunder shall relieve the
Borrower of any of the Obligations or any of its existing obligations to such
Bank arising under other agreements or instruments.

    Section 14.3.  REMEDIES. In the event that one or more Events of Default
shall have occurred and be continuing, whether or not the Banks shall have
accelerated the maturity of the Loans pursuant to Section 14.1, the Majority
Banks may direct the Agent to proceed to protect and enforce the rights and
remedies of the Agent and the Banks under this Agreement, the Notes, any or all
of the other Loan Documents or under applicable law by suit in equity, action at
law or other appropriate proceeding (including for the specific performance of
any covenant or agreement contained in this Agreement or the other Loan
Documents or any instrument pursuant to which the Obligations are evidenced and,
to the full extent permitted by applicable law, the obtaining of the EX PARTE
appointment of a receiver), and, if any amount shall have become due, by
declaration or otherwise, proceed to enforce the payment thereof or any other
legal or equitable right or remedy of the Agent and the Banks under the Loan
Documents or applicable law. No remedy herein conferred upon the Banks or the
Agent or the holder of any Note or purchaser of any Letter of Credit
Participation is intended to be exclusive of any other remedy and each and every
remedy shall be cumulative and shall be in addition to every other remedy

                                      -96-
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given hereunder or under any of the other Loan Documents or now or hereafter
existing at law or in equity or by statute or any other provision of law.

    Section 15.    SETOFF. Neither the Agent nor any of the Banks shall have any
right of set-off or the like with respect to the Obligations against any assets
of the Borrower, BPI, their respective Subsidiaries or any Partially-Owned
Entity.

    Section 16.    THE AGENT.

    Section 16.1.  AUTHORIZATION. (a) The Agent is authorized to take such
action on behalf of each of the Banks and to exercise all such powers as are
hereunder and under any of the other Loan Documents and any related documents
delegated to the Agent, together with such powers as are reasonably incident
thereto, PROVIDED that no duties or responsibilities not expressly assumed
herein or therein shall be implied to have been assumed by the Agent. The
relationship between the Agent and the Banks is and shall be that of agent and
principal only, and nothing contained in this Agreement or any of the other Loan
Documents shall be construed to constitute the Agent as a trustee or fiduciary
for any Bank.

                   (b) The Borrower, without further inquiry or investigation,
shall, and is hereby authorized by the Banks to, assume that all actions taken
by the Agent hereunder and in connection with or under the Loan Documents are
duly authorized by the Banks. The Banks shall notify Borrower of any successor
to Agent by a writing signed by Majority Banks, which successor shall be
reasonably acceptable to the Borrower so long as no Default or Event of Default
has occurred and is continuing. The Borrower acknowledges that any Bank which
acquires Fleet is acceptable as a successor to the Agent.

    Section 16.2.  EMPLOYEES AND AGENTS. The Agent may exercise its powers and
execute its duties by or through employees or agents and shall be entitled to
take, and to rely on, advice of counsel concerning all matters pertaining to its
rights and duties under this Agreement and the other Loan Documents. The Agent
may utilize the services of such Persons as the Agent in its sole discretion may
reasonably determine, and all reasonable fees and expenses of any such Persons
shall be paid by the Borrower.

    Section 16.3.  NO LIABILITY. Neither the Agent, nor any of its shareholders,
directors, officers or employees nor any other Person assisting them in their
duties nor any agent or employee thereof, shall be liable for any waiver,
consent or approval given or any action taken, or omitted to be taken, in good
faith by it or them hereunder or under any of the other Loan Documents, or in
connection herewith or therewith, or be responsible for the consequences of any
oversight or error of judgment whatsoever, except that the Agent may be liable
for losses due to its willful misconduct or gross negligence.

                                      -97-
<Page>

    Section 16.4.  NO REPRESENTATIONS. The Agent shall not be responsible for
the execution or validity or enforceability of this Agreement, the Notes, the
Letters of Credit, or any of the other Loan Documents or for the validity,
enforceability or collectibility of any such amounts owing with respect to the
Notes, or for any recitals or statements, warranties or representations made
herein or in any of the other Loan Documents or in any certificate or instrument
hereafter furnished to it by or on behalf of BPI or the Borrower or any of their
respective Subsidiaries, or be bound to ascertain or inquire as to the
performance or observance of any of the terms, conditions, covenants or
agreements in this Agreement or the other Loan Documents. The Agent shall not be
bound to ascertain whether any notice, consent, waiver or request delivered to
it by the Borrower or BPI or any holder of any of the Notes shall have been duly
authorized or is true, accurate and complete. The Agent has not made nor does it
now make any representations or warranties, express or implied, nor does it
assume any liability to the Banks, with respect to the credit worthiness or
financial condition of the Borrower or any of its Subsidiaries or BPI or any of
the Subsidiaries or any tenant under a Lease or any other entity. Each Bank
acknowledges that it has, independently and without reliance upon the Agent or
any other Bank, and based upon such information and documents as it has deemed
appropriate, made its own credit analysis and decision to enter into this
Agreement.

    Section 16.5.  PAYMENTS.

                   (a) A payment by the Borrower to the Agent hereunder or any
of the other Loan Documents for the account of any Bank shall constitute a
payment to such Bank. The Agent agrees to distribute to each Bank such Bank's
PRO RATA share of payments received by the Agent for the account of the Banks,
as provided herein or in any of the other Loan Documents. All such payments
shall be made on the date received, if before 1:00 p.m., and if after 1:00 p.m.,
on the next Business Day. If payment is not made on the day received, the funds
shall be invested by the Agent in overnight obligations, and interest thereon
paid PRO RATA to the Banks.

                   (b) If in the reasonable opinion of the Agent the
distribution of any amount received by it in such capacity hereunder, under the
Notes or under any of the other Loan Documents might involve it in material
liability, it may refrain from making distribution until its right to make
distribution shall have been adjudicated by a court of competent jurisdiction,
PROVIDED that the Agent shall invest any such undistributed amounts in overnight
obligations on behalf of the Banks and interest thereon shall be paid PRO RATA
to the Banks. If a court of competent jurisdiction shall adjudge that any amount
received and distributed by the Agent is to be repaid, each Person to whom any
such distribution shall have been made shall either repay to the Agent its
proportionate share of the amount so adjudged to be repaid or shall pay over the
same in such manner and to such Persons as shall be determined by such court.

                   (c) Notwithstanding anything to the contrary contained in
this Agreement or any of the other Loan Documents, any Bank that fails (i) to
make available

                                      -98-
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to the Agent its PRO RATA share of any Loan or to purchase any Letter of Credit
Participation or (ii) to adjust promptly such Bank's outstanding principal and
its PRO rata Commitment Percentage as provided in Section 2.1, shall be deemed
delinquent (a "Delinquent Bank") and shall be deemed a Delinquent Bank until
such time as such delinquency is satisfied. A Delinquent Bank shall be deemed to
have assigned any and all payments due to it from the Borrower, whether on
account of outstanding Loans, interest, fees or otherwise, to the remaining
nondelinquent Banks for application to, and reduction of, their respective PRO
RATA shares of all outstanding Loans. The Delinquent Bank hereby authorizes the
Agent to distribute such payments to the nondelinquent Banks in proportion to
their respective PRO RATA shares of all outstanding Loans. If not previously
satisfied directly by the Delinquent Bank, a Delinquent Bank shall be deemed to
have satisfied in full a delinquency when and if, as a result of application of
the assigned payments to all outstanding Loans of the nondelinquent Banks, the
Banks' respective PRO RATA shares of all outstanding Loans have returned to
those in effect immediately prior to such delinquency and without giving effect
to the nonpayment causing such delinquency.

    Section 16.6.  HOLDERS OF NOTES. The Agent may deem and treat the payee of
any Notes or the purchaser of any Letter of Credit Participation as the absolute
owner or purchaser thereof for all purposes hereof until it shall have been
furnished in writing with a different name by such payee or by a subsequent
holder, assignee or transferee.

    Section 16.7.  INDEMNITY. The Banks ratably and severally agree hereby to
indemnify and hold harmless the Agent and its Affiliates from and against any
and all claims, actions and suits (whether groundless or otherwise), losses,
damages, costs, expenses (including any expenses for which the Agent has not
been reimbursed by the Borrower as required by Section 17), and liabilities of
every nature and character arising out of or related to this Agreement, the
Notes, or any of the other Loan Documents or the transactions contemplated or
evidenced hereby or thereby, or the Agent's actions taken hereunder or
thereunder, except to the extent that any of the same shall be directly caused
by the Agent's willful misconduct or gross negligence.

    Section 16.8.  AGENT AS BANK. In its individual capacity as a Bank, Fleet
shall have the same obligations and the same rights, powers and privileges in
respect to its Commitment and the Loans made by it, and as the holder of any of
the Notes and as the purchaser of any Letter of Credit Participations, as it
would have were it not also the Agent.

    Section 16.9.  NOTIFICATION OF DEFAULTS AND EVENTS OF DEFAULT. Each Bank
hereby agrees that, upon learning of the existence of a Default or an Event of
Default, it shall (to the extent notice has not previously been provided)
promptly notify the Agent thereof. The Agent hereby agrees that upon receipt of
any notice under this Section 16.9 it shall promptly notify the other Banks of
the existence of such Default or Event of Default.

    Section 16.10. DUTIES IN THE CASE OF ENFORCEMENT. In case one or more Events
of Default have occurred and shall be continuing, and whether or not
acceleration of the

                                      -99-
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Obligations shall have occurred, the Agent shall, if (a) so requested by the
Majority Banks and (b) the Banks have provided to the Agent such additional
indemnities and assurances against expenses and liabilities as the Agent may
reasonably request, proceed to enforce the provisions of this Agreement and
exercise all or any such other legal and equitable and other rights or remedies
as it may have in respect of enforcement of the Banks' rights against the
Borrower and its Subsidiaries under this Agreement and the other Loan Documents.
The Majority Banks may direct the Agent in writing as to the method and the
extent of any such enforcement, the Banks (including any Bank which is not one
of the Majority Banks) hereby agreeing to ratably and severally indemnify and
hold the Agent harmless from all liabilities incurred in respect of all actions
taken or omitted in accordance with such directions, PROVIDED that the Agent
need not comply with any such direction to the extent that the Agent reasonably
believes the Agent's compliance with such direction to be unlawful or
commercially unreasonable in any applicable jurisdiction.

    Section 16.11. SUCCESSOR AGENT. Fleet, or any successor Agent, may resign as
Agent at any time by giving at least 30 days prior written notice thereof to the
Banks and to the Borrower. The Majority Banks may remove the Agent in the event
of the Agent's willful misconduct or gross negligence or in the event that the
Agent ceases to hold a Commitment under this Agreement. In addition, the
Borrower may remove the Agent in the event that the Agent holds (without
participation) less than the Minimum Commitment, PROVIDED that if the Agent
holds less than the Minimum Commitment at any time as a result of the merger or
consolidation of any of the other Banks or as a result of events other than the
sale by the Agent of any portion of its Commitment, the Agent shall have a
period of ninety (90) days after its failure to hold at least the Minimum
Commitment to cure such failure. Any such resignation or removal shall be
effective upon appointment and acceptance of a successor Agent, as hereinafter
provided. Upon any such resignation or removal, the Majority Banks shall have
the right to appoint a successor Agent, which is a Bank under this Agreement and
which holds at least the Minimum Commitment, PROVIDED that so long as no Default
or Event of Default has occurred and is continuing the Borrower shall have the
right to approve any successor Agent, which approval shall not be unreasonably
withheld. If, in the case of a resignation by the Agent, no successor Agent
shall have been so appointed by the Majority Banks and approved by the Borrower,
and shall have accepted such appointment, within thirty (30) days after the
retiring Agent's giving of notice of resignation, then the retiring Agent may,
on behalf of the Banks, appoint any one of the other Banks as a successor Agent.
The Borrower acknowledges that any Bank which acquires Fleet is acceptable as a
successor Agent. Upon the acceptance of any appointment as Agent hereunder by a
successor Agent, such successor Agent shall thereupon succeed to and become
vested with all the rights, powers, privileges and duties of the retiring or
removed Agent, and the retiring or removed Agent shall be discharged from all
further duties and obligations as Agent under this Agreement. After any Agent's
resignation or removal hereunder as Agent, the provisions of this Section 16
shall inure to its benefit as to any actions taken or omitted to be

                                      -100-
<Page>

taken by it while it was Agent under this Agreement. The Agent agrees that it
shall not assign any of its rights or duties as Agent to any other Person.

    Section 16.12. NOTICES. Any notices or other information required hereunder
to be provided to the Agent (with copies to the Agent for each Bank) shall be
forwarded by the Agent to each of the Banks on the same day (if practicable)
and, in any case, on the next Business Day following the Agent's receipt thereof

    Section 17.    EXPENSES. The Borrower agrees to pay (a) the reasonable costs
of producing and reproducing this Agreement, the other Loan Documents and the
other agreements and instruments mentioned herein, (b) the reasonable fees,
expenses and disbursements of the Agent's outside counsel or any local counsel
to the Agent incurred in connection with the preparation, administration or
interpretation of the Loan Documents and other instruments mentioned herein,
each closing hereunder, and amendments, modifications, approvals, consents or
waivers hereto or hereunder, (c) the fees, expenses and disbursements of the
Agent incurred by the Agent in connection with the preparation, administration
or interpretation of the Loan Documents and other instruments mentioned herein,
including, without limitation, the costs incurred by the Agent in connection
with its inspection of the Borrowing Base Properties (subject to Section 12.14),
and, without double-counting amounts under clause (b) above, the fees and
disbursements of the Agent's counsel in preparing the documentation, (d) the
fees, costs, expenses and disbursements of the Agent and its Affiliates incurred
in connection with the initial syndication and/or participations of the Loans
(whether occurring before or after the closing hereunder), including, without
limitation, reasonable legal fees, travel costs, costs of preparing syndication
materials and photocopying costs, PROVIDED that the Borrower shall not incur any
costs or fees of any kind in connection with any participation, sale or other
syndication of any portion of the Loans which occurs after the initial
syndication other than reasonable legal fees and expenses incurred in connection
with any participation, sale or syndication undertaken at the request of the
Borrower or (in addition to any other fees or expenses relating thereto) in
connection with an amendment or increase to the amount of the Total Commitment,
(e) all reasonable expenses (including reasonable attorneys' fees and costs,
which attorneys may be employees of any Bank or the Agent, and the fees and
costs of engineers, investment bankers, or other experts retained by any Bank or
the Agent in connection with any such enforcement proceedings) incurred by any
Bank or the Agent in connection with (i) the enforcement of or preservation of
rights under any of the Loan Documents against the Borrower or any of its
Subsidiaries or BPI or the administration thereof after the occurrence and
during the continuance of a Default or Event of Default (including, without
limitation, expenses incurred in any restructuring and/or "workout" of the
Loans), and (ii) any litigation, proceeding or dispute whether arising hereunder
or otherwise, in any way related to any Bank's or the Agent's relationship with
the Borrower or any of its Subsidiaries or BPI, (f) all reasonable fees,
expenses and disbursements of the Agent incurred in connection with UCC
searches, UCC terminations or mortgage discharges, and (g) all costs incurred by
the Agent in the future in connection with its inspection of the Borrowing Base
Properties, PROVIDED that

                                      -101-
<Page>

prior to the occurrence of an Event of Default, the Borrower shall not be
required to pay for more than one inspection of each Borrowing Base Property per
year. The covenants of this Section 17 shall survive the repayment of the
amounts owing under the Notes and this Agreement and the termination of this
Agreement and the obligations of the Banks hereunder.

    Section 18.    INDEMNIFICATION. The Borrower agrees to indemnify and hold
harmless the Agent and each of the Banks and the shareholders, directors,
agents, officers, subsidiaries and affiliates of the Agent and each of the Banks
from and against any and all claims, actions and suits, whether groundless or
otherwise, and from and against any and all liabilities, losses (including
amounts, if any, owing to any Bank pursuant to Section Section 5.4, 5.5, 5.6 and
5.8), settlement payments, obligations, damages and expenses of every nature and
character in connection therewith, arising out of this Agreement or any of the
other Loan Documents or the transactions contemplated hereby or thereby or which
otherwise arise in connection with the financing, including, without limitation,
(a) any actual or proposed use by the Borrower or any of its Subsidiaries of the
proceeds of any of the Loans, (b) the Borrower or any of its Subsidiaries
entering into or performing this Agreement or any of the other Loan Documents,
or (c) pursuant to Section 8.17, in each case including, without limitation, the
reasonable fees and disbursements of counsel and allocated costs of internal
counsel incurred in connection with any such investigation, litigation or other
proceeding, PROVIDED, HOWEVER, that the Borrower shall not be obligated under
this Section 18 to indemnify any Person for liabilities arising from such
Person's own gross negligence, willful misconduct or breach of this Agreement.
In litigation, or the preparation therefor, the Borrower shall be entitled to
select counsel reasonably acceptable to the Majority Banks, and the Agent (as
approved by the Majority Banks) shall be entitled to select their own
supervisory counsel, and, in addition to the foregoing indemnity, the Borrower
agrees to pay promptly the reasonable fees and expenses of each such counsel.
Prior to any settlement of any such litigation by the Banks, the Banks shall
provide the Borrower and BPI with notice and an opportunity to address any of
their concerns with the Banks, and the Banks shall not settle any litigation
without first obtaining Borrower's consent thereto, which consent shall not be
unreasonably withheld or delayed. If and to the extent that the obligations of
the Borrower under this Section 18 are unenforceable for any reason, the
Borrower hereby agrees to make the maximum contribution to the payment in
satisfaction of such obligations which is permissible under applicable law. The
provisions of this Section 18 shall survive the repayment of the amounts owing
under the Notes and this Agreement and the termination of this Agreement and the
obligations of the Banks hereunder and shall continue in full force and effect
as long as the possibility of any such claim, action, cause of action or suit
exists.

    Section 19.    SURVIVAL OF COVENANTS, ETC. All covenants, agreements,
representations and warranties made herein, in the Notes, in any of the other
Loan Documents or in any documents or other papers delivered by or on behalf of
the Borrower or any of its Subsidiaries or BPI pursuant hereto shall be deemed
to have been relied upon

                                      -102-
<Page>

by the Banks and the Agent, notwithstanding any investigation heretofore or
hereafter made by any of them, and shall survive the making by the Banks of any
of the Loans and the issuance, extension or renewal of any Letters of Credit, as
herein contemplated, and shall continue in full force and effect so long as any
Letter of Credit or any amount due under this Agreement or the Notes or any of
the other Loan Documents remains outstanding or any Bank has any obligation to
make any Loans or the Agent or any Fronting Bank has any obligation to issue,
extend or renew any Letter of Credit. The indemnification obligations of the
Borrower provided herein and in the other Loan Documents shall survive the full
repayment of amounts due and the termination of the obligations of the Banks
hereunder and thereunder to the extent provided herein and therein. All
statements contained in any certificate or other paper delivered to any Bank or
the Agent at any time by or on behalf of the Borrower or any of its Subsidiaries
or BPI pursuant hereto or in connection with the transactions contemplated
hereby shall constitute representations and warranties by the Borrower or such
Subsidiary or BPI hereunder.

    Section 20.    ASSIGNMENT; PARTICIPATIONS; ETC.

    Section 20.1.  CONDITIONS TO ASSIGNMENT BY BANKS. Except as provided herein,
each Bank may assign to one or more Eligible Assignees all or a portion of its
interests, rights and obligations under this Agreement (including all or a
portion of its Commitment Percentage and Commitment and the same portion of the
Loans at the time owing to it, the Notes held by it and its participating
interest in the risk relating to any Letters of Credit); PROVIDED that (a) the
Agent and, other than during an Event of Default, the Borrower each shall have
the right to approve any Eligible Assignee, which approval shall not be
unreasonably withheld or delayed, it being agreed that the Agent and the
Borrower must approve or reject a proposed Eligible Assignee within seven (7)
days of receiving a written request from any Bank for such approval (PROVIDED
that the request for approval, and the envelope in which it is delivered, is
conspicuously marked with the following legend: "REQUEST FOR APPROVAL -- TIME
SENSITIVE -- MUST RESPOND WITHIN SEVEN (7) DAYS") and if the Agent or the
Borrower fails to respond within such seven (7) day period, such request for
approval shall be deemed approved by the Agent or the Borrower, or both, as the
case may be, (b) each such assignment shall be of a constant, and not a varying,
percentage of all the assigning Bank's rights and obligations under this
Agreement, (c) subject to the provisions of Section 2.7, each Bank shall have at
all times an amount of its Commitment of not less than $10,000,000 unless
otherwise consented to by the Agent and, other than during an Event of Default,
the Borrower and (d) the parties to such assignment shall execute and deliver to
the Agent, for recording in the Register (as hereinafter defined), an assignment
and assumption, substantially in the form of EXHIBIT F hereto (an "Assignment
and Assumption"), together with any Notes subject to such assignment. Upon such
execution, delivery, acceptance and recording, from and after the effective date
specified in each Assignment and Assumption, which effective date shall be at
least two (2) Business Days after the execution thereof unless otherwise agreed
by the Agent (PROVIDED

                                      -103-
<Page>

any assignee has assumed the obligation to fund any outstanding Eurodollar Rate
Loans), (i) the assignee thereunder shall be a party hereto and, to the extent
provided in such Assignment and Assumption, have the rights and obligations of a
Bank hereunder and thereunder, and (ii) the assigning Bank shall, to the extent
provided in such assignment and upon payment to the Agent of the registration
fee referred to in Section 20.3, be released from its obligations under this
Agreement. Any such Assignment and Assumption shall run to the benefit of the
Borrower and a copy of any such Assignment and Assumption shall be delivered by
the Assignor to the Borrower.

    Notwithstanding the provisions of subclause (a) of the preceding paragraph,
any Bank may, without the consent of the Borrower, make an assignment otherwise
permitted hereunder to (x) another Bank, and (y) an Affiliate of such Bank,
PROVIDED that such Affiliate is an Eligible Assignee. Without limiting the
provisions of Section 17, with respect to an assignment by a Bank to its
Affiliate or to another Bank which does not require the consent of the Borrower,
unless such assignment occurs at the request of the Borrower, the Borrower shall
not be responsible for any costs or expenses attributable to such assignment,
all of which shall be payable by the assigning Bank.

    Section 20.2.  CERTAIN REPRESENTATIONS AND WARRANTIES; LIMITATIONS;
COVENANTS. By executing and delivering an Assignment and Assumption, the parties
to the assignment thereunder confirm to and agree with each other and the other
parties hereto as follows: (a) other than the representation and warranty that
it is the legal and beneficial owner of the interest being assigned thereby free
and clear of any adverse claim, the assigning Bank makes no representation or
warranty and assumes no responsibility with respect to any statements,
warranties or representations made in or in connection with this Agreement or
the execution, legality, validity, enforceability, genuineness, sufficiency or
value of this Agreement, the other Loan Documents or any other instrument or
document furnished pursuant hereto; (b) the assigning Bank makes no
representation or warranty and assumes no responsibility with respect to the
financial condition of the Borrower and its Subsidiaries or BPI or any other
Person primarily or secondarily liable in respect of any of the Obligations, or
the performance or observance by the Borrower and its Subsidiaries or BPI or any
other Person primarily or secondarily liable in respect of any of the
Obligations of any of their obligations under this Agreement or any of the other
Loan Documents or any other instrument or document furnished pursuant hereto or
thereto; (c) such assignee confirms that it has received a copy of this
Agreement, together with copies of the most recent financial statements referred
to in Section 7.4 and Section 8.4 and such other documents and information as it
has deemed appropriate to make its own credit analysis and decision to enter
into such Assignment and Assumption; (d) such assignee will, independently and
without reliance upon the assigning Bank, the Agent or any other Bank and based
on such documents and information as it shall deem appropriate at the time,
continue to make its own credit decisions in taking or not taking action under
this Agreement; (e) such assignee represents and warrants that it is an Eligible
Assignee; (f) such assignee appoints and authorizes the Agent to take such
action as agent on its behalf and to exercise such powers under this Agreement
and the other Loan Documents as are

                                      -104-
<Page>

delegated to the Agent by the terms hereof or thereof, together with such powers
as are reasonably incidental thereto; (g) such assignee agrees that it will
perform in accordance with their terms all of the obligations that by the terms
of this Agreement are required to be performed by it as a Bank; (h) such
assignee represents and warrants that it is legally authorized to enter into
such Assignment and Assumption; and (i) such assignee acknowledges that it has
made arrangements with the assigning Bank satisfactory to such assignee with
respect to its pro rata share of Letter of Credit Fees in respect of outstanding
Letters of Credit.

    Section 20.3.  REGISTER. The Agent shall maintain a copy of each Assignment
and Assumption delivered to it and a register or similar list (the "Register")
for the recordation of the names and addresses of the Banks and the Commitment
Percentages of, and principal amount of the Loans owing to, the Banks from time
to time. The entries in the Register shall be conclusive, in the absence of
manifest error, and the Borrower, the Agent and the Banks may treat each Person
whose name is recorded in the Register as a Bank hereunder for all purposes of
this Agreement. The Register shall be available for inspection by the Borrower
and the Banks at any reasonable time and from time to time upon reasonable prior
notice. Upon each such recordation, the assigning Bank agrees to pay to the
Agent a registration fee in the sum of $2,500.

    Section 20.4.  NEW NOTES. Upon its receipt of an Assignment and Assumption
executed by the parties to such assignment, together with each Note subject to
such assignment, the Agent shall (a) record the information contained therein in
the Register, and (b) give prompt notice thereof to the Borrower and the Banks
(other than the assigning Bank). Unless done simultaneously with the Assignment
and Assumption, within two (2) Business Days after receipt of such notice, the
Borrower, at its own expense, (i) shall execute and deliver to the Agent, in
exchange for each surrendered Revolving Credit Note, a new Revolving Credit Note
and Swingline Note or Bid Rate Note, if applicable, to the order of such
Eligible Assignee in an amount equal to the amount assumed by such Eligible
Assignee pursuant to such Assignment and Assumption and, if the assigning Bank
has retained some portion of its obligations hereunder, a new Revolving Credit
Note and other Note, if applicable, to the order of the assigning Bank in an
amount equal to the amount retained by it hereunder and (ii) shall deliver an
opinion from counsel to the Borrower in substantially the form delivered on the
Closing Date pursuant to Section 12.9 as to such new Notes. Such new Notes shall
provide that they are replacements for the surrendered Notes, shall be in an
aggregate principal amount equal to the aggregate principal amount of the
surrendered Notes, shall be dated the effective date of such Assignment and
Assumption and shall otherwise be in substantially the form of the assigned
Notes. The surrendered Notes shall be canceled and returned to the Borrower.

    Section 20.5.  PARTICIPATIONS. Each Bank may sell participations to one or
more banks or other entities in all or a portion of such Bank's rights and
obligations under this Agreement and the other Loan Documents; provided that (a)
each such participation shall be in an amount of not less than $10,000,000, (b)
any such sale or participation shall not

                                      -105-
<Page>

affect the rights and duties of the selling Bank hereunder to the Borrower and
the Agent and the Bank shall continue to exercise all approvals, disapprovals
and other functions of a Bank, (c) the only rights granted to the participant
pursuant to such participation arrangements with respect to waivers, amendments
or modifications of, or approvals under, the Loan Documents shall be the rights
to approve waivers, amendments or modifications that would reduce the principal
of or the interest rate on any Loans, extend the term or increase the amount of
the Commitment of such Bank as it relates to such participant, reduce the amount
of any fees to which such participant is entitled or extend any regularly
scheduled payment date for principal or interest, and (d) no participant shall
have the right to grant further participations or assign its rights, obligations
or interests under such participation to other Persons without the prior written
consent of the Agent, which consent shall not be unreasonably withheld.

    Section 20.6.  PLEDGE BY LENDER. Notwithstanding any other provision of this
Agreement, any Bank at no cost to the Borrower may at any time pledge all or any
portion of its interest and rights under this Agreement (including all or any
portion of its Notes) to any of the twelve Federal Reserve Banks organized under
Section 4 of the Federal Reserve Act, 12 U.S.C. Section 341. No such pledge or
the enforcement thereof shall release the pledgor Bank from its obligations
hereunder or under any of the other Loan Documents.

    Section 20.7.  NO ASSIGNMENT BY BORROWER. The Borrower shall not assign or
transfer any of its rights or obligations under any of the Loan Documents
without prior Unanimous Bank Approval.

    Section 20.8.  DISCLOSURE. The Borrower agrees that, in addition to
disclosures made in accordance with standard banking practices, any Bank may
disclose information obtained by such Bank pursuant to this Agreement to
assignees or participants and potential assignees or participants hereunder. Any
such disclosed information shall be treated by any assignee or participant with
the same standard of confidentiality set forth in Section 8.10.

    Section 20.9.  SYNDICATION. The Borrower acknowledges that each of the Agent
and the Arranger intends, and shall have the right, by itself or through its
Affiliates, to syndicate or enter into co-lending arrangements with respect to
the Loans and the Total Commitment pursuant to this Section 20, and the Borrower
agrees to cooperate with the Agent's and the Arranger's and their Affiliate's
syndication and/or co-lending efforts, such cooperation to include, without
limitation, the provision of information reasonably requested by potential
syndicate members.

    Section 21.    NOTICES, ETC. Except as otherwise expressly provided in this
Agreement, all notices and other communications made or required to be given
pursuant to this Agreement or the Notes or any Letter of Credit Applications
shall be in writing and shall be delivered in hand, mailed by United States
registered or certified first class mail, postage prepaid, sent by overnight
courier, or sent by facsimile and confirmed by delivery via courier or postal
service, addressed as follows:

                                      -106-
<Page>

                   (a) if to the Borrower or BPI, at Boston Properties, Inc.,
111 Huntington Avenue, Boston, Massachusetts 02199, Attention: Mr. Douglas T.
Linde, Senior Vice President and Chief Financial Officer, with a copy to the
General Counsel of BPLP at the address for the Borrower set forth above and to
Ross D. Gillman, Esq., Goodwin Procter LLP, 599 Lexington Avenue, New York, New
York 10022, or to such other address for notice as the Borrower or BPI shall
have last furnished in writing to the Agent;

                   (b) if to the Agent, to the Real Estate Finance Department at
100 Federal Street, Boston, Massachusetts 02110, with a copy to Robert C. Avil,
Director, Fleet National Bank, 115 Perimeter Center Place, Suite 500, Atlanta,
Georgia 30346, or such other address for notice as the Agent shall have last
furnished in writing to the Borrower, with a copy to Michael J. Haroz, Esq.,
Goulston & Storrs, 400 Atlantic Avenue, Boston, Massachusetts 02110-3333, or at
such other address for notice as the Agent shall last have furnished in writing
to the Person giving the notice; and

                   (c) if to any Bank, at such Bank's address set forth ON
SCHEDULE 2 hereto, or such other address for notice as such Bank shall have last
furnished in writing to the Person giving the notice.

Any such notice or demand shall be deemed to have been duly given or made and to
have become effective (i) if delivered by hand, overnight courier, or facsimile
to the party to which it is directed, at the time of the receipt thereof by such
party or the sending of such facsimile and (ii) if sent by registered or
certified first-class mail, postage prepaid, on the third Business Day following
the mailing thereof.

    Section 22.    BPLP AS AGENT FOR THE BORROWER. The Borrower (other than
BPLP) hereby appoints BPLP as its agent with respect to the receiving and giving
of any notices, requests, instructions, reports, certificates (including,
without limitation, compliance certificates), schedules, revisions, financial
statements or any other written or oral communications hereunder. The Agent and
each Bank is hereby entitled to rely on any communications given or transmitted
by BPLP as if such communication were given or transmitted by each and every
Borrower; PROVIDED HOWEVER, that any communication given or transmitted by any
Borrower other than BPLP shall be binding with respect to such Borrower. Any
communication given or transmitted by the Agent or any Bank to BPLP shall be
deemed given and transmitted to each and every Borrower.

    Section 23.    GOVERNING LAW; CONSENT TO JURISDICTION AND SERVICE. THIS
AGREEMENT AND EACH OF THE OTHER LOAN DOCUMENTS, EXCEPT AS OTHERWISE SPECIFICALLY
PROVIDED THEREIN, ARE CONTRACTS UNDER THE LAWS OF THE COMMONWEALTH OF
MASSACHUSETTS AND SHALL FOR ALL PURPOSES BE CONSTRUED IN ACCORDANCE WITH AND
GOVERNED BY THE LAWS OF SUCH COMMONWEALTH (EXCLUDING THE

                                      -107-
<Page>

LAWS APPLICABLE TO CONFLICTS OR CHOICE OF LAW). EACH OF THE BORROWER AND ITS
SUBSIDIARIES AGREES THAT ANY SUIT FOR THE ENFORCEMENT OF THIS AGREEMENT OR ANY
OF THE OTHER LOAN DOCUMENTS MAY BE BROUGHT IN THE COURTS OF THE COMMONWEALTH OF
MASSACHUSETTS SITTING IN SUFFOLK COUNTY OR ANY FEDERAL COURT SITTING IN THE
EASTERN DISTRICT OF MASSACHUSETTS AND CONSENTS TO THE NON-EXCLUSIVE JURISDICTION
OF SUCH COURTS AND THE SERVICE OF PROCESS IN ANY SUCH SUIT BEING MADE UPON THE
BORROWER OR ITS SUBSIDIARIES BY MAIL AT THE ADDRESS SPECIFIED IN Section 21. THE
BORROWER AND ITS SUBSIDIARIES HEREBY WAIVE ANY OBJECTION THAT ANY OF THEM MAY
NOW OR HEREAFTER HAVE TO THE VENUE OF ANY SUCH SUIT OR ANY SUCH COURT OR THAT
SUCH SUIT IS BROUGHT IN AN INCONVENIENT COURT.

    Section 24.    HEADINGS. The captions in this Agreement are for convenience
of reference only and shall not define or limit the provisions hereof.

    Section 25.    COUNTERPARTS. This Agreement and any amendment hereof may be
executed in several counterparts and by each party on a separate counterpart,
each of which when so executed and delivered shall be an original, and all of
which together shall constitute one instrument. In proving this Agreement it
shall not be necessary to produce or account for more than one such counterpart
signed by the party against whom enforcement is sought.

    Section 26.    ENTIRE AGREEMENT, ETC. The Loan Documents and any other
documents executed in connection herewith or therewith express the entire
understanding of the parties with respect to the transactions contemplated
hereby. Neither this Agreement nor any term hereof may be changed, waived,
discharged or terminated, except as provided in Section 27.

    Section 27.    WAIVER OF JURY TRIAL AND CERTAIN DAMAGE CLAIMS. EXCEPT TO THE
EXTENT EXPRESSLY PROHIBITED BY LAW, THE BORROWER AND ITS SUBSIDIARIES HEREBY
WAIVE THEIR RESPECTIVE RIGHTS TO A JURY TRIAL WITH RESPECT TO ANY ACTION OR
CLAIM ARISING OUT OF ANY DISPUTE IN CONNECTION WITH THIS AGREEMENT, THE NOTES OR
ANY OF THE OTHER LOAN DOCUMENTS, ANY RIGHTS OR OBLIGATIONS HEREUNDER OR
THEREUNDER OR THE PERFORMANCE OF SUCH RIGHTS AND OBLIGATIONS. EXCEPT TO THE
EXTENT EXPRESSLY PROHIBITED BY LAW, THE BORROWER AND ITS SUBSIDIARIES HEREBY
WAIVE ANY RIGHT ANY OF THEM MAY HAVE TO CLAIM OR RECOVER IN ANY LITIGATION
REFERRED TO IN THE PRECEDING SENTENCE ANY SPECIAL, EXEMPLARY, PUNITIVE OR
CONSEQUENTIAL DAMAGES OR ANY DAMAGES OTHER THAN, OR IN ADDITION TO, ACTUAL
DAMAGES, INCLUDING ANY DAMAGES PURSUANT TO M.G.L. C. 93A ET SEQ. EACH OF

                                      -108-
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THE BORROWER AND ITS SUBSIDIARIES (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR
ATTORNEY OF ANY BANK OR THE AGENT HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT
SUCH BANK OR THE AGENT WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE
THE FOREGOING WAIVERS AND (B) ACKNOWLEDGES THAT THE AGENT AND THE BANKS HAVE
BEEN INDUCED TO ENTER INTO THIS AGREEMENT AND THE OTHER LOAN DOCUMENTS TO WHICH
THEY ARE PARTIES BY, AMONG OTHER THINGS, THE WAIVERS AND CERTIFICATIONS
CONTAINED HEREIN.

    Section 28.    CONSENTS, AMENDMENTS, WAIVERS, ETC. Except as otherwise
expressly provided in this Agreement, any consent or approval required or
permitted by this Agreement may be given, and any term of this Agreement or of
any of the other Loan Documents may be amended, and the performance or
observance by the Borrower or BPI or any of their respective Subsidiaries of any
terms of this Agreement or the other Loan Documents or the continuance of any
Default or Event of Default may be waived (either generally or in a particular
instance and either retroactively or prospectively) with, but only with, the
written consent of the Majority Banks.

    Notwithstanding the foregoing, Unanimous Bank Approval shall be required for
any amendment, modification or waiver of this Agreement that:

                            (i)   reduces or forgives any principal of any
                       unpaid Loan or any interest thereon (including any
                       interest "breakage" costs) or any fees due any Bank
                       hereunder, or permits any prepayment not otherwise
                       permitted hereunder; or

                            (ii)  changes the unpaid principal amount of any
                       Loan, reduces the rate of interest applicable to any
                       Loan, or reduces any fee payable to the Banks hereunder;
                       or

                            (iii) changes the date fixed for any payment of
                       principal of or interest on any Loan (including, without
                       limitation, any extension of the Maturity Date) or any
                       fees payable hereunder (including, without limitation,
                       the waiver of any monetary Event of Default); or

                            (iv)  changes the amount of any Bank's Commitment
                       (other than pursuant to an assignment permitted under
                       Section 20.1) or increases the amount of the Total
                       Commitment except as permitted hereunder; or

                            (v)   modifies any provision herein or in any other
                       Loan Document which by the terms thereof expressly
                       requires Unanimous Bank Approval; or

                                      -109-
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                            (vi)  changes the definitions of Majority Banks,
                       Required Banks or Unanimous Bank Approval.

    No waiver shall extend to or affect any obligation not expressly waived or
impair any right consequent thereon. No course of dealing or delay or omission
on the part of the Agent or the Banks or any Bank in exercising any right shall
operate as a waiver thereof or otherwise be prejudicial to such right or any
other rights of the Agent or the Banks. No notice to or demand upon the Borrower
shall entitle the Borrower to other or further notice or demand in similar or
other circumstances.

    Notwithstanding the foregoing, the Required Banks shall be required for any
amendment, modification or waiver of this agreement that:

                            (i)   amends any of the covenants contained in
                       Section 10.1 through Section 10.7, inclusive or amends
                       any of the definitions which are financial terms
                       contained therein, or

                            (ii)  amends any of the provisions governing funding
                       contained in Section 2, or

                            (iii) changes the rights, duties or obligations of
                       the Agent specified in Section 16 (PROVIDED that no
                       amendment or modification to such Section 16 or to the
                       fee payable to the Agent under this Agreement may be made
                       without the prior written consent of the Agent and that
                       the waiver of any fee payable to the Agent shall require
                       only the consent of the Agent).

    In addition, no amendment or modification to or waiver of the provisions of
Section 2.8 may be made without the prior written consent of the Swingline
Lender and, without limitation of the provisions requiring Unanimous Bank
Approval or the consent of the Required Banks, no amendment or modification to
or waiver of the provisions of Section 2.9 may be made without the prior written
consent of those Banks holding more than 50% of the outstanding Bid Rate Loans
at the applicable time of reference.

    Section 29.    SEVERABILITY. The provisions of this Agreement are severable,
and if any one clause or provision hereof shall be held invalid or unenforceable
in whole or in part in any jurisdiction, then such invalidity or
unenforceability shall affect only such clause or provision, or part thereof, in
such jurisdiction, and shall not in any manner affect such clause or provision
in any other jurisdiction, or any other clause or provision of this Agreement in
any jurisdiction.

                                      -110-
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    Section 30.    INTEREST RATE LIMITATION. Notwithstanding anything herein to
the contrary, if at any time the interest rate applicable to any Loan, together
with all fees, charges and other amounts which are treated as interest on such
Loan under applicable law (collectively, the "Charges"), shall exceed the
maximum lawful rate (the "Maximum Rate") which may be contracted for, charged,
taken, received or reserved by the Bank holding such Loan in accordance with
applicable law, the rate of interest payable in respect of such Loan hereunder,
together with all Charges payable in respect thereof, shall be limited to the
Maximum Rate and, to the extent lawful, the interest and Charges that would have
been payable in respect of such Loan but were not payable as a result of the
operation of this Section 30 shall be cumulated and the interest and Charges
payable to such Bank in respect of other Loans or periods shall be increased
(but not above the Maximum Rate therefor) until such cumulated amount, together
with interest thereon at the Federal Funds Rate to the date of repayment, shall
have been received by such Bank.

                  (Remainder of page intentionally left blank)

                                      -111-
<Page>

    IN WITNESS WHEREOF, the undersigned have duly executed this Agreement as a
sealed instrument as of the date first set forth above.

                                 FLEET NATIONAL BANK,
                                 Individually and as Managing Administrative
                                 Agent

                                 By: /s/ Jeff Z. Aycock
                                    ------------------------------------------
                                 Name: Jeff Z. Aycock
                                 Title: Vice President

                                 BANK OF AMERICA, N.A.,
                                 Individually and as Syndication Agent

                                 By: /s/ Lesa J. Butler
                                    ------------------------------------------
                                 Name: Lesa J. Butler
                                 Title: Principal

                                 COMMERZBANK AG NEW YORK AND
                                 GRAND CAYMAN BRANCHES,
                                 Individually and as Co-Documentation Agent

                                 By: /s/ Christian Berry
                                    ------------------------------------------
                                 Name: Christian Berry
                                 Title: Vice President

                                 By: /s/ Douglas Traynor
                                    ------------------------------------------
                                 Name: Douglas Traynor
                                 Title: Senior Vice President

                       [Signatures continued on next page]

                                      -112-
<Page>

                                 JPMORGAN CHASE BANK,
                                 Individually and as Co-Documentation Agent

                                 By: /s/ Marc E. Costantino
                                    ------------------------------------------
                                 Name: Marc E. Costantino
                                 Title: Vice President

                                 WELLS FARGO BANK NATIONAL
                                 ASSOCIATION,
                                 Individually and as Co-Documentation Agent

                                 By: /s/ Douglas S. Novitch
                                    ------------------------------------------
                                 Name: Douglas S. Novitch
                                 Title: Authorized Officer

                                 PNC BANK, NATIONAL ASSOCIATION

                                 By: /s/ James Colella
                                    ------------------------------------------
                                 Name: James Colella
                                 Title: Vice President

                                 THE BANK OF NEW YORK

                                 By: /s/ Rick Laudisi
                                    ------------------------------------------
                                 Name: Rick Laudisi
                                 Title: Vice President

                       [Signatures continued on next page]

                                      -113-
<Page>

                                 CITICORP NORTH AMERICA, INC.

                                 By: /s/ Andrew Robinson
                                    ------------------------------------------
                                 Name: Andrew Robinson
                                 Title: Vice President

                                 BAYERISCHE HYPO-UND VEREINSBANK
                                 AG, NEW YORK BRANCH

                                 By: /s/ Helga Blum
                                    ------------------------------------------
                                 Name: Helga Blum
                                 Title: Director

                                 DEUTSCHE BANK TRUST COMPANY AMERICAS

                                 By: /s/ Linda Wang
                                    ------------------------------------------
                                 Name: Linda Wang
                                 Title: Vice President

                                 KEYBANK, N.A.

                                 By: /s/ John C. Scott
                                    ------------------------------------------
                                 Name: John C. Scott
                                 Title: Assistant Vice President

                       [Signatures continued on next page]

                                      -114-
<Page>

                                 DRESDNER BANK AG, NEW YORK AND
                                 GRAND CAYMAN BRANCHES

                                 By: /s/ Peter Tzelios
                                    ------------------------------------------
                                 Name: Peter Tzelios
                                 Title: Director

                                 By: /s/ David Sarner
                                    ------------------------------------------
                                 Name: David Sarner
                                 Title: Associate

                                 CITIZENS BANK

                                 By: /s/ Daniel Ouellette
                                    ------------------------------------------
                                 Name: Daniel Ouellette
                                 Title: Senior Vice President

                                      -115-
<Page>

                                 332 HARTWELL AVENUE, LEXINGTON, MA**

                                 MBZ-LEX TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 WALTHAM OFFICE CENTER, WALTHAM, MA

                                 ZEE EM TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

----------
** The designation of the specific Real Estate Asset or Assets owned by any
signatory to this Agreement or any other Loan Document is for informational
purposes only and does not in any way limit the joint and several liability of
each Borrower, for so long as it is a Borrower, for the Obligations.

                                      -116-
<Page>

                                 204 SECOND AVENUE, WALTHAM, MA

                                 WP TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 170 TRACER LANE, WALTHAM, MA

                                 TRACER LANE TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      -117-
<Page>

                                 33 HAYDEN AVENUE, LEXINGTON, MA

                                 HAYDEN OFFICE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 92 AND 100 HAYDEN AVENUE, LEXINGTON, MA

                                 92 HAYDEN AVENUE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      -118-
<Page>

                                 LEXINGTON OFFICE PARK, 420-430 BEDFORD STREET,
                                 LEXINGTON, MA

                                 ELANDZEE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 40-46 HARVARD STREET, WESTWOOD, MA

                                 40-46 HARVARD STREET TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      -119-
<Page>

                                 17 HARTWELL AVENUE, LEXINGTON, MA

                                 ZEE BEE TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 ONE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 ONE CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      -120-
<Page>

                                 THREE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 THREE CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 ELEVEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 ELEVEN CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      -121-
<Page>

                                 FOURTEEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 FOURTEEN CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 500 E STREET, S.W., WASHINGTON, D.C.

                                 SCHOOL STREET ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its sole general
                                      partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                      -122-
<Page>

                                 LONG WHARF MARRIOTT, BOSTON, MA

                                 DOWNTOWN BOSTON PROPERTIES TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 CAMBRIDGE CENTER MARRIOTT, CAMBRIDGE, MA

                                 TWO CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      -123-
<Page>

                                 DECOVERLY TWO, ROCKVILLE, MD

                                 DECOVERLY TWO LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its Managing Member

                                           By:  Boston Properties, Inc.,
                                                its general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 THE CANDLER BUILDING, 111 MARKET PLACE,
                                 BALTIMORE, MD

                                 CANDLER ASSOCIATES L.L.C.

                                 By:  Boston Properties Limited Partnership,
                                      its managing member

                                      By:  Boston Properties, Inc.,
                                           its general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      -124-
<Page>

                                 104 CARNEGIE CENTER, PRINCETON, NJ

                                 CARNEGIE CENTER ASSOCIATES

                                 By:  Boston Properties Limited Partnership, its
                                      general partner

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 105 CARNEGIE CENTER, PRINCETON, NJ

                                 CARNEGIE CENTER ASSOCIATES

                                 By:  Boston Properties Limited Partnership, its
                                      general partner

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      -125-
<Page>

                                 210 CARNEGIE CENTER, PRINCETON, NJ

                                 210 ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 211 CARNEGIE CENTER, PRINCETON, NJ

                                 211 ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                      -126-
<Page>

                                 CAMBRIDGE CENTER NORTH GARAGE, CAMBRIDGE, MA

                                 CAMBRIDGE CENTER NORTH TRUST

                                 By:  Boston Properties Limited Partnership, its
                                      beneficiary

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 9509 KEY WEST AVENUE, DECOVERLY SEVEN,
                                 ROCKVILLE, MD

                                 DECOVERLY SEVEN LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                      -127-
<Page>

                                 ONE TOWER CENTER, EAST BRUNSWICK, NJ

                                 SCV PARTNERS

                                 By:  BP III LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 201 CARNEGIE CENTER, PRINCETON, NJ

                                 PRINCETON CHILDCARE ASSOCIATES
                                 LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its sole general
                                      partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                      -128-
<Page>

                                 399 PARK AVENUE, NEW YORK, NY

                                 195 WEST STREET, WALTHAM, MA

                                 7435 BOSTON BOULEVARD, BUILDING ONE,
                                 SPRINGFIELD, VA

                                 7451 BOSTON BOULEVARD, BUILDING TWO,
                                 SPRINGFIELD, VA

                                 7374 BOSTON BOULEVARD, BUILDING FOUR,
                                 SPRINGFIELD, VA

                                 8000 GRAINGER COURT, BUILDING FIVE,
                                 SPRINGFIELD, VA

                                 7500 BOULEVARD, BUILDING SIX,
                                 SPRINGFIELD, VA

                                 7501 BOSTON BOULEVARD, BUILDING SEVEN,
                                 SPRINGFIELD, VA

                                 7601 BOSTON BOULEVARD, BUILDING EIGHT,
                                 SPRINGFIELD, VA

                                 7375 BOSTON BOULEVARD, BUILDING TEN,
                                 SPRINGFIELD, VA

                                 7300 BOSTON BOULEVARD, BUILDING THIRTEEN,
                                 SPRINGFIELD, VA

                                 8000 CORPORATE COURT, BUILDING ELEVEN,
                                 SPRINGFIELD, VA

                                 38 CABOT BOULEVARD, BUCKS COUNTY, PA

                                 365 HERNDON PARKWAY (SUGARLAND I),
                                 HERNDON, VA

                                 397 HERNDON PARKWAY (SUGARLAND II),
                                 HERNDON, VA

                                      -129-
<Page>

                                 164 LEXINGTON ROAD, BILLERICA, MA

                                 THE ARBORETUM, 12700 SUNRISE VALLEY DRIVE,
                                 RESTON, VA

                                 502 CARNEGIE CENTER, PRINCETON, NJ

                                 RESIDENCE INN, CAMBRIDGE, MA

                                 212 CARNEGIE CENTER, PRINCETON, NJ

                                 NEWPORT OFFICE CENTER, QUINCY, MA

                                 ORBITAL SCIENCES - PHASE I, DULLES, VA

                                 DECOVERLY THREE, 15204 OMEGA DRIVE, ROCKVILLE,
                                 MD

                                 7450 BOSTON BOULEVARD, BUILDING THREE,
                                 SPRINGFIELD, VA

                                 200 WEST STREET, WALTHAM, MA

                                 Broad Run Business Park Building E,
                                 MORAN ROAD, LEESBURG VA

                                 BOSTON PROPERTIES LIMITED PARTNERSHIP

                                 By:  Boston Properties, Inc., its sole general
                                      partner

                                      By: /s/ Douglas T. Linde
                                         -------------------(SEAL)
                                         Douglas T. Linde
                                         Senior Vice President and
                                         Chief Financial Officer

                       [Signatures continued on next page]

                                      -130-
<Page>

ACKNOWLEDGED AND AGREED:

BOSTON PROPERTIES, INC.

By: /s/ Douglas T. Linde
   -------------------(SEAL)
   Douglas T. Linde
   Senior Vice President and
   Chief Financial Officer

                                      -131-
<Page>

                                   SCHEDULE 1

                                  MBZ-LEX Trust
                                 ZEE EM Trust II
                                    WP Trust
                              Tracer Lane Trust II
                               Hayden Office Trust
                             92 Hayden Avenue Trust
                                 Elandzee Trust
                           40-46 Harvard Street Trust
                                ZEE BEE Trust II
                           One Cambridge Center Trust
                          Three Cambridge Center Trust
                          Eleven Cambridge Center Trust
                         Fourteen Cambridge Center Trust
                  School Street Associates Limited Partnership
                        Downtown Boston Properties Trust
                           Two Cambridge Center Trust
                        Decoverly Two Limited Partnership
                            Candler Associates L.L.C.
                           Carnegie Center Associates
                       210 Associates Limited Partnership
                       211 Associates Limited Partnership
                          Cambridge Center North Trust
                       Decoverly Seven Limited Partnership
                                  SCV Partners
               Princeton Childcare Associates Limited Partnership

                                      S1-1
<Page>

                                   SCHEDULE 2

<Table>
<Caption>
Bank                                            Commitment Amount            Commitment Percentage
----                                            -----------------            ---------------------
<S>                                                <C>                               <C>
Fleet National Bank                                $  68,500,000                     11.32%
One Federal Street
Boston, MA 02109

Bank of America, N.A.                              $  68,500,000                     11.32%
TX1-492-64-01
901 Main Street
64th Floor
Dallas, TX  75202-3714

Commerzbank AG New York and                        $  56,000,000                      9.26%
Grand Cayman Branches
2 World Financial Center
New York, NY  10281-1050

JPMorgan Chase Bank                                $  56,000,000                      9.26%
270 Park Avenue
New York, NY  10017

Wells Fargo Bank National Association              $  56,000,000                      9.26%
121 High Street, 5th Floor
Boston, MA  02110

PNC Bank, National Association                     $  40,000,000                      6.61%
One PNC Plaza
249 Fifth Avenue
Mail Stop P1-P0PP-19-2
Pittsburgh, PA  15222

The Bank of New York                               $  40,000,000                      6.61%
One Wall Street
New York, NY  10286

Bayerische Hypo- Und Vereinsbank                   $  40,000,000                      6.61%
  AG, New York Branch
150 East 42nd Street
New York, NY  10017-4679
</Table>

                                      S2-1
<Page>

<Table>
<S>                                                <C>                                <C>
Dresdner Bank AG, New York and Grand Cayman        $  40,000,000                      6.61%
  Branches
75 Wall Street
New York, NY  10005

Citicorp North America, Inc.                       $  40,000,000                      6.61%
399 Park Avenue, 16th Floor
New York, NY  10043

KeyBank, N.A.                                      $  40,000,000                      6.61%
127 Public Square
Cleveland, OH  44114

Deutsche Bank Trust Company Americas               $  35,000,000                      5.79%
c/o Deutsche Bank Securities, Inc.
200 Crescent Court
Suite 550
Dallas, TX  75201

Citizens Bank                                      $  25,000,000                      4.13%
28 State Street
Boston, MA  02109

TOTAL                                              $ 605,000,000                       100%
</Table>

                                      S2-2
<Page>

                                   SCHEDULE 3
                            BORROWING BASE PROPERTIES

32 Hartwell Avenue, Lexington, MA

Waltham Office Center, Waltham, MA

204 Second Avenue, Waltham, MA

170 Tracer Lane, Waltham, MA

33 Hayden Avenue, Lexington, MA

92 & 100 Hayden Avenue, Lexington, MA

Lexington Office Park, 420-430 Bedford Street, Lexington, MA

40-46 Harvard Street, Westwood, MA

17 Hartwell Avenue, Lexington, MA

One Cambridge Center, Cambridge, MA

Three Cambridge Center, Cambridge, MA

Eleven Cambridge Center, Cambridge, MA

Fourteen Cambridge Center, Cambridge, MA

500 E Street, S.W., Washington, D.C.

Long Wharf Marriott, Boston, MA

Cambridge Center Marriott, Cambridge, MA

Decoverly Two, Rockville, MD

Decoverly Seven, 9509 Key West Avenue, Rockville, MD

The Candler Building, 111 Market Place, Baltimore, MD

One Tower Center, East Brunswick, NJ

104 Carnegie Center, Princeton, NJ

105 Carnegie Center, Princeton, NJ

210 Carnegie Center, Princeton, NJ

211 Carnegie Center, Princeton, NJ

212 Carnegie Center, Princeton, NJ

                                      S3-1
<Page>

Cambridge Center North Garage, Cambridge, MA

195 West Street, Waltham, MA

7435 Boston Boulevard, Building One, Springfield, VA

7451 Boston Boulevard, Building Two, Springfield, VA

7374 Boston Boulevard, Building Four, Springfield, VA

8000 Grainger Court, Building Five, Springfield, VA

7500 Boston Boulevard, Building Six, Springfield, VA

7501 Boston Boulevard, Building Seven, Springfield, VA

7601 Boston Boulevard, Building Eight, Springfield, VA

7375 Boston Boulevard, Building Ten, Springfield, VA

8000 Corporate Court, Building Eleven, Springfield, VA

7300 Boston Boulevard, Building Thirteen, Springfield, VA

38 Cabot Boulevard, Bucks County, PA

365 Herndon Parkway (Sugarland I), Herndon, VA

397 Herndon Parkway (Sugarland II), Herndon, VA

164 Lexington Road, Billerica, MA

The Arboretum, 12700 Sunrise Valley Drive, Reston, VA

502 Carnegie Center, Princeton, NJ

Residence Inn, Cambridge, MA

Decoverly Three, 15204 Omega Drive, Rockville, MD

7450 Boston Boulevard, Building Three, Springfield, VA

200 West Street, Waltham, MA

Newport Office Park, Quincy, MA

Orbital Sciences-Phase I, Dulles, VA

399 Park Avenue, New York, NY

201 Carnegie Center, Princeton, NJ

Broad Run Business Park Building E, Moran Road, Leesburg, VA

                                      S3-2
<Page>

                                   SCHEDULE 4

                                 CBD PROPERTIES

1 Cambridge Center

3 Cambridge Center

8 Cambridge Center

10 Cambridge Center

11 Cambridge Center

14 Cambridge Center

Cambridge Center North Garage

Long Wharf Marriott Hotel

One Embarcadero Center

Two Embarcadero Center

Three Embarcadero Center

Four Embarcadero Center

Federal Reserve Building

Embarcadero Center West Tower

599 Lexington Avenue

Metropolitan Square

901 New York Avenue

1301 New York Avenue

Capital Gallery

280 Park Avenue

Prudential Tower

Antenna Income @ Pru Tower

101 Huntington Avenue

The Shops at the Prudential Center

                                      S4-1
<Page>

Lord & Taylors @ Prudential Center

Saks @ Prudential Center

Shaw's Supermarket @ Prudential Center (currently under development)

Prudential Center Garage

500 E Street

Sumner Square

875 Third Avenue

2300 N Street

111 Huntington Avenue

Times Square Tower (Site 1)

5 Times Square

University Place

399 Park Avenue

Citigroup Center

265 Franklin Street

Market Square North

                                      S4-2
<Page>

                                 SCHEDULE 7.1(b)

                            PREFERRED CREDITOR EQUITY

                                      None.

                                    S7.1(b)-1
<Page>

                                  SCHEDULE 7.7

                                   LITIGATION

                                      None.

                                     S7.7-1
<Page>

                                  SCHEDULE 7.16

                             EMPLOYEE BENEFIT PLANS

Boston Properties maintains a supplemental retirement plan for a very limited
number of specified non-senior executive officer employees. In addition, Boston
Properties is obligated to make contributions or other payments to retirement
plans on behalf of certain employees located in New York City pursuant to
collective bargaining agreements to which Boston Properties is bound. These
obligations are not, individually or in the aggregate, material to BPI, BPLP or,
taken as a whole, the BP Group.

                                     S7.16-1
<Page>

                                  SCHEDULE 7.19

                                  SUBSIDIARIES

                               See attached chart

                                     S7.19-1
<Page>

                                 SCHEDULE 8.5(b)

                              ENVIRONMENTAL MATTERS

          Those matters identified in the Form 10-K filed with BPI with the SEC
for fiscal year 2001 on pages 13-14 therein.

                                    S8.5(b)-1
<Page>

                                 SCHEDULE 9.1(e)

                                 BPI LIABILITIES

Liabilities relating to organizational matters (including liabilities of BPI as
the general partner of the Borrower and as a partner or member of subsidiaries
of the Borrower).

Liabilities relating to 100 East Pratt Street, Baltimore, Maryland.

Liabilities arising in connection with service contracts, management contracts,
employment and employee-benefit related agreements, letters of intent, brokerage
agreements, confidentiality agreements, development agreements and similar types
of agreements.

Liabilities arising in connection with litigation or other similar actions
arising in the ordinary course of business.

Liabilities of the same or similar kind or nature as those liabilities described
above which are not, individually or in the aggregate, material to BPI, BPLP or,
taken as a whole, the BP Group

                                    S9.1(e)-1
<Page>

                                  SCHEDULE 9.3

                                   INVESTMENTS

                 See attached chart (identical to Schedule 7.19)

                                     S9.3-1
<Page>

                                                                       EXHIBIT A

                             [AMENDED AND RESTATED]

                              REVOLVING CREDIT NOTE

$_______________                                         Date: ______________

    FOR VALUE RECEIVED, the undersigned Boston Properties Limited Partnership, a
Delaware limited partnership, and each of the other undersigned parties and
other parties who are or from time to time become a Borrower under (and as
defined in) the Revolving Credit Agreement referred to below ______________
(hereinafter, together with their respective successors in title and assigns,
collectively called the "Borrower"), by this promissory note (hereinafter,
called "this Note"), absolutely and unconditionally and jointly and severally
promise to pay to the order of (hereinafter, together with its successors in
title and assigns, called the "Bank"), the principal sum of
_______________________________ Million and 00/100 Dollars ($___________), or
so much thereof as shall have been advanced by the Bank to the Borrower by way
of Revolving Credit Loans under (and as defined in) the Revolving Credit
Agreement and shall remain outstanding, such payment to be made as hereinafter
provided, and to pay interest on the principal sum outstanding hereunder from
time to time from and after the date hereof until the said principal sum or the
unpaid portion thereof shall have become due and payable as hereinafter
provided.

    Capitalized terms used herein without definition shall have the meanings set
forth in the Revolving Credit Agreement.

    The unpaid principal (not at the time overdue) under this Note shall bear
interest at the rate or rates from time to time in effect under the Revolving
Credit Agreement. Accrued interest on the unpaid principal under this Note shall
be payable on the dates specified in the Revolving Credit Agreement.

    On the Maturity Date there shall become absolutely due and payable by the
Borrower hereunder, and the Borrower hereby promises to pay to the Bank, the
balance (if any) of the principal hereof then remaining unpaid, all of the
unpaid interest accrued hereon and all (if any) other amounts payable on or in
respect of this Note or the indebtedness evidenced hereby.

    Each overdue amount (whether of principal, interest or otherwise) payable on
or in respect of this Note or the indebtedness evidenced hereby shall (to the
extent permitted by applicable law) bear interest at the rates and on the terms
provided in the Revolving Credit Agreement. The unpaid interest accrued on each
overdue amount in accordance with the foregoing terms of this paragraph shall
become and be absolutely due and payable by the Borrower to Bank on demand by
the Agent. Interest on each overdue

                                       A-1
<Page>

amount will continue to accrue as provided by the foregoing terms of this
paragraph, and will (to the extent permitted by applicable law) be compounded
daily until the obligations of the Borrower in respect of the payment of such
overdue amount shall be discharged (whether before or after judgment).

    Each payment of principal, interest or other sum payable on or in respect of
this Note or the indebtedness evidenced hereby shall be made by the Borrower
directly to the Agent in Dollars, for the account of the Bank, at the Agent's
Head Office, on the due date of such payment, and in immediately available and
freely transferable funds. All payments on or in respect of this Note or the
indebtedness evidenced hereby shall be made without set-off or counterclaim and
free and clear of and without any deductions, withholdings, restrictions or
conditions of any nature.

    This Note is made and delivered by the Borrower to the Bank pursuant to a
Third Amended and Restated Revolving Credit Agreement, dated as of January __,
2003, among (i) the Borrower, (ii) the Banks party thereto and (iii) the Bank[,
in its capacity as a Bank and as Agent] (hereinafter, as originally executed,
and as varied, supplemented, amended and/or restated, called the "Revolving
Credit Agreement"). This Note evidences the obligations of the Borrower (a) to
repay the principal amount of the Bank's Commitment Percentage of the Revolving
Credit Loans made by the Bank to the Borrower pursuant to the Revolving Credit
Agreement; (b) to pay interest, as herein provided, on the principal amount
hereof remaining unpaid from time to time; and (c) to pay other amounts which
may become due and payable hereunder or thereunder. Reference is hereby made to
the Revolving Credit Agreement (including the EXHIBITS annexed thereto) for a
complete statement of the terms thereof.

    The Borrower has the right to prepay the unpaid principal of this Note in
full or in part upon the terms contained in the Revolving Credit Agreement. The
Borrower has an obligation to prepay principal of this Note from time to time if
and to the extent required under, and upon the terms contained in, the Revolving
Credit Agreement. Any partial payment of the indebtedness evidenced by this Note
shall be applied in accordance with the terms of the Revolving Credit Agreement.

    Pursuant to and upon the terms contained in Section 14 of the Revolving
Credit Agreement, the entire unpaid principal of this Note, all of the interest
accrued on the unpaid principal of this Note and all (if any) other amounts
payable on or in respect of this Note or the indebtedness evidenced hereby may
be declared to be immediately due and payable, whereupon the entire unpaid
principal of this Note, all of the interest accrued on the unpaid principal of
this Note and all (if any) other amounts payable on or in respect of this Note
or the indebtedness evidenced hereby shall (if not already due and payable)
forthwith become and be, or the same may, as provided in said Section 14,
automatically become, due and payable to the Bank without presentment, demand,
protest or any other formalities of any kind, all of which are hereby expressly
and irrevocably

                                       A-2
<Page>

waived by the Borrower, excepting only for notice expressly provided for in the
Revolving Credit Agreement.

    All computations of interest payable as provided in this Note shall be made
by the Agent on the basis of the actual number of days elapsed divided by 360.
The interest rate in effect from time to time shall be determined in accordance
with the terms of the Revolving Credit Agreement.

    Should all or any part of the indebtedness represented by this Note be
collected by action at law, or in bankruptcy, insolvency, receivership or other
court proceedings, or should this Note be placed in the hands of attorneys for
collection after default, the Borrower hereby promises to pay to the holder of
this Note, upon demand by the holder hereof at any time, in addition to
principal, interest and all (if any) other amounts payable on or in respect of
this Note or the indebtedness evidenced hereby, all court costs and attorneys'
fees and all other collection charges and expenses reasonably incurred or
sustained by the holder of this Note.

    The Borrower hereby irrevocably waives notice of acceptance, presentment,
notice of nonpayment, protest, notice of protest, suit and all other conditions
precedent in connection with the delivery, acceptance, collection and/or
enforcement of this Note, except for notices expressly provided for in the
Revolving Credit Agreement. The Borrower hereby absolutely and irrevocably
consents and submits to the jurisdiction of the Courts of the Commonwealth of
Massachusetts sitting in Suffolk County and of any Federal Court located in the
Eastern District of Massachusetts in connection with any actions or proceedings
brought against the Borrower by the holder hereof arising out of or relating to
this Note. This Note may be executed in any number of counterparts and by each
party on a separate counterpart, each of which when so executed and delivered
shall be an original, and all of which together shall constitute one instrument.

                  (Remainder of page intentionally left blank)

                                       A-3
<Page>

    This Note is intended to take effect as a sealed instrument. This Note and
the obligations of the Borrower hereunder shall be governed by and interpreted
and determined in accordance with the laws of the Commonwealth of Massachusetts.

    Each Borrower shall be jointly and severally liable for the full amount
owing under this Note.

    IN WITNESS WHEREOF, this REVOLVING CREDIT NOTE has been duly executed by the
undersigned on the day and in the year first above written in Boston,
Massachusetts.

                                 332 HARTWELL AVENUE, LEXINGTON, MA**

                                 MBZ-LEX TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

----------
** The designation of the specific Real Estate Asset or Assets owned by any
signatory to this Agreement or any other Loan Document is for informational
purposes only and does not in any way limit the joint and several liability of
each Borrower, for so long as it is a Borrower, for the Obligations.

                                       A-4
<Page>

                                 WALTHAM OFFICE CENTER, WALTHAM, MA

                                 ZEE EM TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                       A-5
<Page>

                                 204 SECOND AVENUE, WALTHAM, MA

                                 WP TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 170 TRACER LANE, WALTHAM, MA

                                 TRACER LANE TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                       A-6
<Page>

                                 33 HAYDEN AVENUE, LEXINGTON, MA

                                 HAYDEN OFFICE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 92 AND 100 HAYDEN AVENUE, LEXINGTON, MA

                                 92 HAYDEN AVENUE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                       A-7
<Page>

                                 LEXINGTON OFFICE PARK, 420-430 BEDFORD STREET,
                                 LEXINGTON, MA

                                 ELANDZEE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 40-46 HARVARD STREET, WESTWOOD, MA

                                 40-46 HARVARD STREET TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                       A-8
<Page>

                                 17 HARTWELL AVENUE, LEXINGTON, MA

                                 ZEE BEE TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 ONE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 ONE CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                       A-9
<Page>

                                 THREE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 THREE CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 ELEVEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 ELEVEN CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      A-10
<Page>

                                 FOURTEEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 FOURTEEN CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 500 E STREET, S.W., WASHINGTON, D.C.

                                 SCHOOL STREET ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its sole general
                                      partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                      A-11
<Page>

                                 LONG WHARF MARRIOTT, BOSTON, MA

                                 DOWNTOWN BOSTON PROPERTIES TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 CAMBRIDGE CENTER MARRIOTT, CAMBRIDGE, MA

                                 TWO CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      A-12
<Page>

                                 DECOVERLY TWO, ROCKVILLE, MD

                                 DECOVERLY TWO LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its Managing Member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 THE CANDLER BUILDING, 111 MARKET PLACE,
                                 BALTIMORE, MD

                                 CANDLER ASSOCIATES L.L.C.

                                 By:  Boston Properties Limited Partnership,
                                      its managing member

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      A-13
<Page>

                                 104 CARNEGIE CENTER, PRINCETON, NJ

                                 CARNEGIE CENTER ASSOCIATES

                                 By:  Boston Properties Limited Partnership, its
                                      general partner

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 105 CARNEGIE CENTER, PRINCETON, NJ

                                 CARNEGIE CENTER ASSOCIATES

                                 By:  Boston Properties Limited Partnership, its
                                      general partner

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      A-14
<Page>

                                 210 CARNEGIE CENTER, PRINCETON, NJ

                                 210 ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 211 CARNEGIE CENTER, PRINCETON, NJ

                                 211 ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                      A-15
<Page>

                                 CAMBRIDGE CENTER NORTH GARAGE, CAMBRIDGE, MA

                                 CAMBRIDGE CENTER NORTH TRUST

                                 By:  Boston Properties Limited Partnership, its
                                      beneficiary

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              -------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 9509 KEY WEST AVENUE, DECOVERLY SEVEN,
                                 ROCKVILLE, MD

                                 DECOVERLY SEVEN LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                      A-16
<Page>

                                 ONE TOWER CENTER, EAST BRUNSWICK, NJ

                                 SCV PARTNERS

                                 By:  BP III LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 201 CARNEGIE CENTER, PRINCETON, NJ

                                 PRINCETON CHILDCARE ASSOCIATES
                                 LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its sole general
                                      partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   -------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 399 PARK AVENUE, NEW YORK, NY

                                 195 WEST STREET, WALTHAM, MA

                                 7435 BOSTON BOULEVARD, BUILDING ONE,
                                 SPRINGFIELD, VA

                                      A-17
<Page>

                                 7451 BOSTON BOULEVARD, BUILDING TWO,
                                 SPRINGFIELD, VA

                                 7374 BOSTON BOULEVARD, BUILDING FOUR,
                                 SPRINGFIELD, VA

                                 8000 GRAINGER COURT, BUILDING FIVE,
                                 SPRINGFIELD, VA

                                 7500 BOULEVARD, BUILDING SIX,
                                 SPRINGFIELD, VA

                                 7501 BOSTON BOULEVARD, BUILDING SEVEN,
                                 SPRINGFIELD, VA

                                 7601 BOSTON BOULEVARD, BUILDING EIGHT,
                                 SPRINGFIELD, VA

                                 7375 BOSTON BOULEVARD, BUILDING TEN,
                                 SPRINGFIELD, VA

                                 7300 BOSTON BOULEVARD, BUILDING THIRTEEN,
                                 SPRINGFIELD, VA

                                 8000 CORPORATE COURT, BUILDING ELEVEN,
                                 SPRINGFIELD, VA

                                 38 CABOT BOULEVARD, BUCKS COUNTY, PA

                                 365 HERNDON PARKWAY (SUGARLAND I),
                                 HERNDON, VA

                                 397 HERNDON PARKWAY (SUGARLAND II),
                                 HERNDON, VA

                                 164 LEXINGTON ROAD, BILLERICA, MA

                                 THE ARBORETUM, 12700 SUNRISE VALLEY DRIVE,
                                 RESTON, VA

                                 502 CARNEGIE CENTER, PRINCETON, NJ

                                 RESIDENCE INN, CAMBRIDGE, MA

                                      A-18
<Page>

                                 212 CARNEGIE CENTER, PRINCETON, NJ

                                 NEWPORT OFFICE CENTER, QUINCY, MA

                                 ORBITAL SCIENCES - PHASE I, DULLES, VA

                                 DECOVERLY THREE, 15204 OMEGA DRIVE, ROCKVILLE,
                                 MD

                                 7450 BOSTON BOULEVARD, BUILDING THREE,
                                 SPRINGFIELD, VA

                                 200 WEST STREET, WALTHAM, MA

                                 Broad Run Business Park Building E,
                                 MORAN ROAD, LEESBURG VA 20175

                                 BOSTON PROPERTIES LIMITED PARTNERSHIP

                                 By:  Boston Properties, Inc., its sole general
                                      partner

                                      By: /s/ Douglas T. Linde
                                         -------------------------(SEAL)
                                         Douglas T. Linde
                                         Senior Vice President and
                                         Chief Financial Officer

                                      A-19
<Page>

                                                                     EXHIBIT A-1

                                 SWINGLINE NOTE

$60,000,000                                       Date:  January __, 2003

    FOR VALUE RECEIVED, the undersigned Boston Properties Limited Partnership, a
Delaware limited partnership, and each of the other undersigned parties and
other parties who are or from time to time become a Borrower under (and as
defined in) the Revolving Credit Agreement referred to below (hereinafter,
together with their respective successors in title and assigns, collectively
called the "Borrower"), by this promissory note (hereinafter, called "this
Note"), absolutely and unconditionally and jointly and severally promise to pay
to the order of FLEET NATIONAL BANK (hereinafter, together with its successors
in title and assigns, called the "Bank"), the principal sum of Sixty Million and
00/100 Dollars ($60,000,000), or so much thereof as shall have been advanced by
the Bank to the Borrower by way of Swingline Loans under (and as defined in) the
Revolving Credit Agreement and shall remain outstanding, such payment to be made
as hereinafter provided, and to pay interest on the principal sum outstanding
hereunder from time to time from and after the date hereof until the said
principal sum or the unpaid portion thereof shall have become due and payable as
hereinafter provided.

    Capitalized terms used herein without definition shall have the meanings set
forth in the Revolving Credit Agreement.

    The unpaid principal (not at the time overdue) under this Note shall bear
interest at the rate or rates from time to time in effect under the Revolving
Credit Agreement. Accrued interest on the unpaid principal under this Note shall
be payable on the dates specified in the Revolving Credit Agreement.

    On the maturity date of any particular Swingline Loan as provided in the
Revolving Credit Agreement, and in any event on the Maturity Date, there shall
become absolutely due and payable by the Borrower hereunder, and the Borrower
hereby promises to pay to the Bank, the balance (if any) of the principal hereof
then remaining unpaid, all of the unpaid interest accrued hereon and all (if
any) other amounts payable on or in respect of this Note or the indebtedness
evidenced hereby.

    Each overdue amount (whether of principal, interest or otherwise) payable on
or in respect of this Note or the indebtedness evidenced hereby shall (to the
extent permitted by applicable law) bear interest at the rates and on the terms
provided in the Revolving Credit Agreement. The unpaid interest accrued on each
overdue amount in accordance with the foregoing terms of this paragraph shall
become and be absolutely due and payable by the Borrower to Bank on demand by
the Agent. Interest on each overdue

                                      A-1-1
<Page>

amount will continue to accrue as provided by the foregoing terms of this
paragraph, and will (to the extent permitted by applicable law) be compounded
daily until the obligations of the Borrower in respect of the payment of such
overdue amount shall be discharged (whether before or after judgment).

    Each payment of principal, interest or other sum payable on or in respect of
this Note or the indebtedness evidenced hereby shall be made by the Borrower
directly to the Agent in Dollars, for the account of the Bank, at the Agent's
Head Office, on the due date of such payment, and in immediately available and
freely transferable funds. All payments on or in respect of this Note or the
indebtedness evidenced hereby shall be made without set-off or counterclaim and
free and clear of and without any deductions, withholdings, restrictions or
conditions of any nature.

    This Note is made and delivered by the Borrower to the Bank pursuant to a
Third Amended and Restated Revolving Credit Agreement, dated as of January __,
2003, among (i) the Borrower, (ii) the Banks party thereto and (iii) the Bank,
in its capacity as a Bank and as Agent (hereinafter, as originally executed, and
as varied, supplemented, amended and/or restated, called the "Revolving Credit
Agreement"). This Note evidences the obligations of the Borrower (a) to repay
the principal amount of the Swingline Loans made by the Bank to the Borrower
pursuant to the Revolving Credit Agreement; (b) to pay interest, as herein
provided, on the principal amount hereof remaining unpaid from time to time; and
(c) to pay other amounts which may become due and payable hereunder or
thereunder. Reference is hereby made to the Revolving Credit Agreement
(including the EXHIBITS annexed thereto) for a complete statement of the terms
thereof.

    The Borrower has the right to prepay the unpaid principal of this Note in
full or in part upon the terms contained in the Revolving Credit Agreement. The
Borrower has an obligation to prepay principal of this Note from time to time if
and to the extent required under, and upon the terms contained in, the Revolving
Credit Agreement. Any partial payment of the indebtedness evidenced by this Note
shall be applied in accordance with the terms of the Revolving Credit Agreement.

    Pursuant to and upon the terms contained in Section 14 of the Revolving
Credit Agreement, the entire unpaid principal of this Note, all of the interest
accrued on the unpaid principal of this Note and all (if any) other amounts
payable on or in respect of this Note or the indebtedness evidenced hereby may
be declared to be immediately due and payable, whereupon the entire unpaid
principal of this Note, all of the interest accrued on the unpaid principal of
this Note and all (if any) other amounts payable on or in respect of this Note
or the indebtedness evidenced hereby shall (if not already due and payable)
forthwith become and be, or the same may, as provided in said Section 14,
automatically become, due and payable to the Bank without presentment, demand,
protest or any other formalities of any kind, all of which are hereby expressly
and irrevocably

                                      A-1-2
<Page>

waived by the Borrower, excepting only for notice expressly provided for in the
Revolving Credit Agreement.

    All computations of interest payable as provided in this Note shall be made
by the Agent on the basis of the actual number of days elapsed divided by 360.
The interest rate in effect from time to time shall be determined in accordance
with the terms of the Revolving Credit Agreement.

    Should all or any part of the indebtedness represented by this Note be
collected by action at law, or in bankruptcy, insolvency, receivership or other
court proceedings, or should this Note be placed in the hands of attorneys for
collection after default, the Borrower hereby promises to pay to the holder of
this Note, upon demand by the holder hereof at any time, in addition to
principal, interest and all (if any) other amounts payable on or in respect of
this Note or the indebtedness evidenced hereby, all court costs and attorneys'
fees and all other collection charges and expenses reasonably incurred or
sustained by the holder of this Note.

    The Borrower hereby irrevocably waives notice of acceptance, presentment,
notice of nonpayment, protest, notice of protest, suit and all other conditions
precedent in connection with the delivery, acceptance, collection and/or
enforcement of this Note, except for notices expressly provided for in the
Revolving Credit Agreement. The Borrower hereby absolutely and irrevocably
consents and submits to the jurisdiction of the Courts of the Commonwealth of
Massachusetts sitting in Suffolk County and of any Federal Court located in the
Eastern District of Massachusetts in connection with any actions or proceedings
brought against the Borrower by the holder hereof arising out of or relating to
this Note. This Note may be executed in any number of counterparts and by each
party on a separate counterpart, each of which when so executed and delivered
shall be an original, and all of which together shall constitute one instrument.

                  (Remainder of page intentionally left blank)

                                      A-1-3
<Page>

    This Note is intended to take effect as a sealed instrument. This Note and
the obligations of the Borrower hereunder shall be governed by and interpreted
and determined in accordance with the laws of the Commonwealth of Massachusetts.

    Each Borrower shall be jointly and severally liable for the full amount
owing under this Note.

    IN WITNESS WHEREOF, this SWINGLINE NOTE has been duly executed by the
undersigned on the day and in the year first above written in Boston,
Massachusetts.

                                 332 HARTWELL AVENUE, LEXINGTON, MA**

                                 MBZ-LEX TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 WALTHAM OFFICE CENTER, WALTHAM, MA

                                 ZEE EM TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President

----------
** The designation of the specific Real Estate Asset or Assets owned by any
signatory to this Agreement or any other Loan Document is for informational
purposes only and does not in any way limit the joint and several liability of
each Borrower, for so long as it is a Borrower, for the Obligations.

                                      A-1-4
<Page>

                                              and Chief Financial Officer

                                      A-1-5
<Page>

                                 204 SECOND AVENUE, WALTHAM, MA

                                 WP TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 170 TRACER LANE, WALTHAM, MA

                                 TRACER LANE TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      A-1-6
<Page>

                                 33 HAYDEN AVENUE, LEXINGTON, MA

                                 HAYDEN OFFICE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 92 AND 100 HAYDEN AVENUE, LEXINGTON, MA

                                 92 HAYDEN AVENUE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      A-1-7
<Page>

                                 LEXINGTON OFFICE PARK, 420-430 BEDFORD STREET,
                                 LEXINGTON, MA

                                 ELANDZEE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 40-46 HARVARD STREET, WESTWOOD, MA

                                 40-46 HARVARD STREET TRUST

                                 By:  Boston Properties Limited Partnership,
                                 its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      A-1-8
<Page>

                                 17 HARTWELL AVENUE, LEXINGTON, MA

                                 ZEE BEE TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 ONE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 ONE CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      A-1-9
<Page>

                                 THREE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 THREE CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 ELEVEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 ELEVEN CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                     A-1-10
<Page>

                                 FOURTEEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 FOURTEEN CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 500 E STREET, S.W., WASHINGTON, D.C.

                                 SCHOOL STREET ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its sole general
                                      partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                     A-1-11
<Page>

                                 LONG WHARF MARRIOTT, BOSTON, MA

                                 DOWNTOWN BOSTON PROPERTIES TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 CAMBRIDGE CENTER MARRIOTT, CAMBRIDGE, MA

                                 TWO CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                     A-1-12
<Page>

                                 DECOVERLY TWO, ROCKVILLE, MD

                                 DECOVERLY TWO LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its Managing Member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 THE CANDLER BUILDING, 111 MARKET PLACE,
                                 BALTIMORE, MD

                                 CANDLER ASSOCIATES L.L.C.

                                 By:  Boston Properties Limited Partnership,
                                      its managing member

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                     A-1-13
<Page>

                                 104 CARNEGIE CENTER, PRINCETON, NJ

                                 CARNEGIE CENTER ASSOCIATES

                                 By:  Boston Properties Limited Partnership, its
                                      general partner

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 105 CARNEGIE CENTER, PRINCETON, NJ

                                 CARNEGIE CENTER ASSOCIATES

                                 By:  Boston Properties Limited Partnership, its
                                      general partner

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                     A-1-14
<Page>

                                 210 CARNEGIE CENTER, PRINCETON, NJ

                                 210 ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 211 CARNEGIE CENTER, PRINCETON, NJ

                                 211 ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                     A-1-15
<Page>

                                 CAMBRIDGE CENTER NORTH GARAGE, CAMBRIDGE, MA

                                 CAMBRIDGE CENTER NORTH TRUST

                                 By:  Boston Properties Limited Partnership, its
                                      beneficiary

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 9509 KEY WEST AVENUE, DECOVERLY SEVEN,
                                 ROCKVILLE, MD

                                 DECOVERLY SEVEN LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                     A-1-16
<Page>

                                 ONE TOWER CENTER, EAST BRUNSWICK, NJ

                                 SCV PARTNERS

                                 By:  BP III LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 201 CARNEGIE CENTER, PRINCETON, NJ

                                 PRINCETON CHILDCARE ASSOCIATES
                                 LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its sole general
                                      partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 399 PARK AVENUE, NEW YORK, NY

                                 195 WEST STREET, WALTHAM, MA

                                 7435 BOSTON BOULEVARD, BUILDING ONE,
                                 SPRINGFIELD, VA

                                     A-1-17
<Page>

                                 7451 BOSTON BOULEVARD, BUILDING TWO,
                                 SPRINGFIELD, VA

                                 7374 BOSTON BOULEVARD, BUILDING FOUR,
                                 SPRINGFIELD, VA

                                 8000 GRAINGER COURT, BUILDING FIVE,
                                 SPRINGFIELD, VA

                                 7500 BOULEVARD, BUILDING SIX,
                                 SPRINGFIELD, VA

                                 7501 BOSTON BOULEVARD, BUILDING SEVEN,
                                 SPRINGFIELD, VA

                                 7601 BOSTON BOULEVARD, BUILDING EIGHT,
                                 SPRINGFIELD, VA

                                 7375 BOSTON BOULEVARD, BUILDING TEN,
                                 SPRINGFIELD, VA

                                 7300 BOSTON BOULEVARD, BUILDING THIRTEEN,
                                 SPRINGFIELD, VA

                                 8000 CORPORATE COURT, BUILDING ELEVEN,
                                 SPRINGFIELD, VA

                                 38 CABOT BOULEVARD, BUCKS COUNTY, PA

                                 365 HERNDON PARKWAY (SUGARLAND I),
                                 HERNDON, VA

                                 397 HERNDON PARKWAY (SUGARLAND II),
                                 HERNDON, VA

                                 164 LEXINGTON ROAD, BILLERICA, MA

                                 THE ARBORETUM, 12700 SUNRISE VALLEY DRIVE,
                                 RESTON, VA

                                 502 CARNEGIE CENTER, PRINCETON, NJ

                                 RESIDENCE INN, CAMBRIDGE, MA

                                     A-1-18
<Page>

                                 212 CARNEGIE CENTER, PRINCETON, NJ

                                 NEWPORT OFFICE CENTER, QUINCY, MA

                                 ORBITAL SCIENCES - PHASE I, DULLES, VA

                                 DECOVERLY THREE, 15204 OMEGA DRIVE, ROCKVILLE,
                                 MD

                                 7450 BOSTON BOULEVARD, BUILDING THREE,
                                 SPRINGFIELD, VA

                                 200 WEST STREET, WALTHAM, MA

                                 Broad Run Business Park Building E,
                                 MORAN ROAD, LEESBURG VA 20175

                                 BOSTON PROPERTIES LIMITED PARTNERSHIP

                                 By:  Boston Properties, Inc., its sole general
                                      partner

                                      By: /s/ Douglas T. Linde
                                         ----------------------(SEAL)
                                         Douglas T. Linde
                                         Senior Vice President and
                                         Chief Financial Officer

                                     A-1-19
<Page>

                                                                       EXHIBIT B

                                  LOAN REQUEST

    This Loan Request is made pursuant to Section 2.4/Section 2.5/Section 2.8 of
the Third Amended and Restated Revolving Credit Agreement dated as of January
__, 2003 among Boston Properties Limited Partnership (the "Borrower"), Fleet
National Bank individually and as Agent, and certain other Banks as provided
therein (as the same may be amended from time to time, the "Credit Agreement").
Unless otherwise defined herein, the terms used in this Loan Request have the
meanings described in the Credit Agreement.

    Each Loan Request submitted by the Borrower shall be a request for a single
Loan or Letter of Credit.

1.  The Borrower hereby requests (check each applicable item):

    / / New Revolving Credit Loan ($_______________)
    / / New Swingline Loan ($______________)
    / / Conversion of Existing Revolving Credit Loan ($_______________)
          (Current Interest Period ending on _________, 20__)
    / / Continuation of Existing Revolving Credit Loan ($_______________)
           (Current Interest Period ending on _________, 20__)
    / / Letter of Credit (Fronting Bank is _____________)

2.  The Type of Loan being requested in this Loan Request (if any) is:

    / / Prime Rate Loan
    / / Eurodollar Rate Loan

3.  The aggregate principal amount of the Loan or the amount of the Letter of
    Credit requested (whether by way of a new advance, continuation or
    conversion) in this Loan Request is:

    $
     ------------------

4.  The proposed Drawdown Date of the Revolving Credit Loan, drawdown date of
    the Swingline Loan or the date of issue, extension or renewal of the Letter
    of Credit requested in this Loan Request is:

    ___________________, 20__

                                       B-1
<Page>

5.  The Interest Period requested for the Loan requested in this Loan Request
    (if any) is:

    _________________ through __________________.

    WITNESS my hand this ____ day of _____________, 20__.

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP, for itself and as agent for
                                 each other Borrower

                                 By:  Boston Properties, Inc., its
                                      general partner

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

                                       B-2
<Page>

                                    EXHIBIT C

                (Exhibit C consists of Exhibits C-1 through C-7)

                                                                     EXHIBIT C-1

         COMPLIANCE CERTIFICATE OF CHIEF FINANCIAL OFFICER, TREASURER OR
                                   CONTROLLER
                                 (Loan Request)

    The undersigned (collectively, the "Borrower") HEREBY CERTIFIES THAT:

    This Compliance Certificate is furnished pursuant to Section 2.4(iv)(c),
Section 2.8, Section 2.9, Section 3.1.1 and/or Section 13.1 of the Third Amended
and Restated Revolving Credit Agreement dated as of January __, 2003 among the
Borrower, Fleet National Bank, individually and as Agent, and certain other
Banks as provided therein (as the same may be amended from time to time, the
"Credit Agreement"). Unless otherwise defined herein, the terms used in this
Compliance Certificate and Schedule 1 attached hereto have the meanings
described in the Credit Agreement.

    Schedule 1 attached hereto sets forth the financial data and computations
evidencing the Borrower's compliance with the covenants contained in Section 10
of the Credit Agreement and with the definition of Borrowing Base Availability
on a pro-forma basis after giving effect to the requested Loan and/or Letter of
Credit, all of which data and computations, to the best knowledge and belief of
the chief financial officer or treasurer executing and delivering this
Compliance Certificate on behalf of the Borrower (the "Chief Financial Officer"
or "Treasurer", as the case may be), are true, complete and correct.

    The activities of the Borrower, BPI and their respective Subsidiaries since
the date of the last Compliance Certificate submitted by the Borrower to the
Agent have been reviewed by the Chief Financial Officer/Treasurer and/or by
employees or agents under his/her immediate supervision. Based upon such review,
to the best knowledge and belief of the Chief Financial Officer/Treasurer, both
before and after giving effect to the requested Loan and/or Letter of Credit,
(1) no Default or Event of Default exists on the date hereof or will exist under
the Credit Agreement or any other Loan Document on the Drawdown Date (or
drawdown date) of such Loan or the date of [issue] [extension or renewal] of
such Letter of Credit, and (2) after taking into account such requested Loan or
Letter of Credit, no Default or Event of Default will exist as of the Drawdown
Date or drawdown date of such Loan or date of [issue] [extension or renewal] of
such Letter of Credit.

    To the best knowledge and belief of the Chief Financial Officer/Treasurer,
each of the representations and warranties of the Borrower and BPI contained in
the Credit

                                      C-1-1
<Page>

Agreement, the other Loan Documents or in any document or instrument delivered
pursuant to or in connection with the Credit Agreement was true as of the date
as of which they were made and is also true at and as of the date hereof and
will be true at and as of the time of the making of the requested Loan or the
[issuance] [extension or renewal] of the requested Letter of Credit, with the
same effect as if made at and as of that time except to the extent that such
representations and warranties relate expressly to an earlier date.

    The Chief Financial Officer/Treasurer/Controller certifies that he/she is
authorized to execute and deliver this Compliance Certificate on behalf of each
Borrower.

    WITNESS my hand this _ day of _______________, 20__

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP, for itself and as agent for
                                 each other Borrower

                                 By:  Boston Properties, Inc., its
                                      general partner

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

                                      C-1-2
<Page>

                                                                     EXHIBIT C-2

                COMPLIANCE CERTIFICATE OF CHIEF FINANCIAL OFFICER
                         (Borrower Financial Statements)

    The undersigned (the "Borrower") HEREBY CERTIFIES THAT:

    This Compliance Certificate is furnished pursuant to Section 8.4(e) of the
Third Amended and Restated Revolving Credit Agreement dated as of January __,
2003 among the Borrower, Fleet National Bank, individually and as Agent, and
certain other Banks as provided therein (as the same may be amended from time to
time, the "Credit Agreement"). Unless otherwise defined herein, the terms used
in this Compliance Certificate and Schedule 1 attached hereto have the meanings
described in the Credit Agreement.

    As required by Section 8.4(e) of the Credit Agreement, financial statements
of the Borrower and its respective subsidiaries (as defined in the Credit
Agreement) for the [year] [quarter] ended 20_ (the "Financial Statements")
prepared in accordance with GAAP (subject, in the case of quarterly statements,
to year-end adjustments none of which are anticipated to be materially adverse,
except as specifically disclosed in this Compliance Certificate) accompany this
Compliance Certificate. The Financial Statements present fairly the financial
position of the Borrower and its subsidiaries (as defined in the Credit
Agreement) as at the date thereof and the results of operations of the Borrower
and its subsidiaries for the period covered thereby.

    Schedule 1 attached hereto sets forth the financial data and computations
evidencing the Borrower's compliance with the covenants contained in Section 10
of the Credit Agreement, all of which data and computations, to the best
knowledge and belief of the chief financial officer executing and delivering
this Compliance Certificate on behalf of the Borrower (the "Chief Financial
Officer"), are true, complete and correct.

    The activities of the Borrower and its Subsidiaries (as defined in the
Credit Agreement) during the period covered by the Financial Statements have
been reviewed by the Chief Financial Officer and/or by employees or agents under
his immediate supervision. Based upon such review, during the period covered by
the Financial Statements, and as of the date of this Certificate, no Default or
Event of Default has occurred and is continuing of which (i) the Borrower has
knowledge, and (ii) the Agent has not previously given notice, except as
specifically disclosed in this Compliance Certificate.

    The Chief Financial Officer certifies that he is authorized to execute and
deliver

                                      C-2-1
<Page>

this Compliance Certificate on behalf of the Borrower.

    WITNESS our hands this ____ day of ___________________, 20__.

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP, for itself and as agent for
                                 each other Borrower

                                 By:  Boston Properties, Inc., its
                                      general partner

                                 By:
                                    --------------------------------
                                        Title:  Chief Financial Officer

                                      C-2-2
<Page>

                                                                     EXHIBIT C-3

                            [Intentionally Omitted.]

                                      C-3-1
<Page>

                                                                     EXHIBIT C-4

              COMPLIANCE CERTIFICATE OF CHIEF FINANCIAL OFFICER OR
                                    TREASURER

               (Disposition/Removal of Borrowing Base Properties)

    The undersigned (the "Borrower") HEREBY CERTIFIES THAT: This Compliance
Certificate is furnished pursuant to Section 8.14/Section 9.4(a) or (b)/Section
14.1 of the Third Amended and Restated Revolving Credit Agreement dated as of
January __, 2003 among the Borrower, Fleet National Bank, individually and as
Agent, and certain other Banks as provided therein (as the same may be amended
from time to time, the "Credit Agreement"). The Borrower hereby gives the Agent
notice of its intention to Sell a Borrowing Base Property or to grant an
Indebtedness Lien on a Borrowing Base Property or remove a Borrowing Base
Property from the Borrowing Base pursuant to Section 8.14/Section 9.4(a) or
(b)/Section 14.1 of the Credit Agreement. Unless otherwise defined herein, the
terms used in this Compliance Certificate and Schedule 1 attached hereto have
the meanings described in the Credit Agreement.

    Schedule 1 attached hereto sets forth the financial data and computations
evidencing the Borrower's compliance with the covenants contained in Section 10
of the Credit Agreement on a PRO FORMA basis after giving effect to such
proposed Sale, Indebtedness Lien or removal of a Real Estate Asset from the
Borrowing Base and all liabilities, fixed or contingent, pursuant thereto, all
of which data and computations, to the best knowledge and belief of the chief
financial officer or treasurer executing and delivering this Compliance
Certificate on behalf of the Borrower (the "Chief Financial Officer" or
"Treasurer", as the case may be), are true, complete and correct.

    The activities of the Borrower, BPI and their respective Subsidiaries (as
defined in the Credit Agreement) have been reviewed by the Chief Financial
Officer/Treasurer and/or by employees or agents under his/her immediate
supervision. Based upon such review, to the best knowledge and belief of the
Chief Financial Officer/Treasurer, both before and after giving effect to the
proposed Sale or Indebtedness Lien, no Default or Event of Default exists or
will exist under any Loan Document.

    The Chief Financial Officer/Treasurer certifies that he/she is authorized to
execute and deliver this Compliance Certificate on behalf of the Borrower and
BPI.

                                      C-4-1
<Page>

    WITNESS our hands this ____ day of _______________, 20__.

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP, for itself and as agent for
                                 each other Borrower

                                 By:  Boston Properties, Inc., its
                                      general partner

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

                                      C-4-2
<Page>

                                                                     EXHIBIT C-5

         COMPLIANCE CERTIFICATE OF CHIEF FINANCIAL OFFICER OR TREASURER
         (Designation of Real Estate Asset as a Borrowing Base Property)

    The undersigned (the "Borrower") HEREBY CERTIFIES THAT:

    This Compliance Certificate is furnished pursuant to the definition of
"Borrowing Base Properties" set forth in Section 1.1 of the Third Amended and
Restated Revolving Credit Agreement dated as of January __, 2003 among the
Borrower, Fleet National Bank, individually and as Agent, and certain other
Banks as provided therein (as the same may be amended from time to time, the
"Credit Agreement"). The Borrower hereby gives the Agent notice of its intention
to designate an Unencumbered Asset as a Borrowing Base Property pursuant to
clause (f) of the definition of "Borrowing Base Properties" set forth in Section
1.1 of the Credit Agreement. Unless otherwise defined herein, the terms used in
this Compliance Certificate and Schedule 1 attached hereto have the meanings
described in the Credit Agreement.

    The designated Unencumbered Asset meets the criteria for Borrowing Base
Properties set forth in Section 1.1 of the Credit Agreement [except
______________].

    Schedule 1 attached hereto sets forth the financial data and computations
evidencing the Borrower's compliance with the covenants contained in Section 10
of the Credit Agreement on a PRO FORMA basis after giving effect to such
proposed designation, all of which data and computations, to the best knowledge
and belief of the chief financial officer or treasurer executing and delivering
this Compliance Certificate on behalf of the Borrower (the "Chief Financial
Officer" or "Treasurer", as the case may be), are true, complete and correct.

    The activities of the Borrower, BPI and their respective Subsidiaries (as
defined in the Credit Agreement) have been reviewed by the Chief Financial
Officer/Treasurer and/or by employees or agents under his/her immediate
supervision. Based upon such review, to the best knowledge and belief of the
Chief Financial Officer/Treasurer, both before and after giving effect to such
designation, no Default or Event of Default exists or will exist under any Loan
Document.

                                      C-5-1
<Page>

    The Chief Financial Officer/Treasurer certifies that he/she is authorized to
execute and deliver this Compliance Certificate on behalf of the Borrower and
BPI.

    WITNESS our hands this ____ day of ____________, 200_.

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP, for itself and as agent for
                                 each other Borrower

                                 By:  Boston Properties, Inc., its
                                      general partner

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

                                      C-5-2
<Page>

                                                                     EXHIBIT C-6

              COMPLIANCE CERTIFICATE OF CHIEF FINANCIAL OFFICER OR
                                    TREASURER

                 (Subsidiary/Non-Borrower Indebtedness Default)

    The undersigned (the "Borrower") HEREBY CERTIFIES THAT: This Compliance
Certificate is furnished pursuant to Section 14.1(f) of the Third Amended and
Restated Revolving Credit Agreement dated as of January __, 2003 among the
Borrower, Fleet National Bank, individually and as Agent, and certain other
Banks as provided therein (as the same may be amended from time to time, the
"Credit Agreement"). The Borrower hereby gives the Agent notice of a condition
described in Section 14.1(f) of the Credit Agreement relating solely to a
non-Borrower Subsidiary or Affiliate of the Borrower (the "Non-Borrower
Entity"). Unless otherwise defined herein, the terms used in this Compliance
Certificate and Schedule 1 attached hereto have the meanings described in the
Credit Agreement.

    Schedule 1 attached hereto sets forth the financial data and computations
evidencing the Borrower's compliance as of the date hereof with the covenants
contained in Section 10 of the Credit Agreement on a PRO FORMA basis after
excluding from the calculation of such covenants the Non-Borrower Entity and all
Real Estate Assets owned by the Non-Borrower Entity, all of which data and
computations, to the best knowledge and belief of the chief financial officer or
treasurer executing and delivering this Compliance Certificate on behalf of the
Borrower (the "Chief Financial Officer" or "Treasurer", as the case may be), are
true, complete and correct.

    The activities of the Borrower, BPI and their respective Subsidiaries have
been reviewed by the Chief Financial Officer/Treasurer and/or by employees or
agents under his/her immediate supervision. Based upon such review, to the best
knowledge and belief of the Chief Financial Officer/Treasurer, after giving
effect to the exclusions discussed in the preceding paragraph, no Default or
Event of Default exists or will exist.

    The Chief Financial Officer/Treasurer certifies that he/she is authorized to
execute and deliver this Compliance Certificate on behalf of the Borrower and
BPI.

                                      C-6-1
<Page>

    WITNESS our hands this ____ day of _______________, 20__.

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP, for itself and as agent for
                                 each other Borrower

                                 By:  Boston Properties, Inc., its
                                      general partner

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

                                      C-6-2
<Page>

                                                                     EXHIBIT C-7

                COMPLIANCE CERTIFICATE OF CHIEF FINANCIAL OFFICER

    The undersigned (the "Borrower") HEREBY CERTIFIES THAT:

    This Compliance Certificate is furnished pursuant to Section 12.17 of the
Third Amended and Restated Revolving Credit Agreement dated as of January __,
2003 among the Borrower, Fleet National Bank, individually and as Agent, and
certain other Banks as provided therein (as the same may be amended from time to
time, the "Credit Agreement"). Unless otherwise defined herein, the terms used
in this Compliance Certificate and Schedule 1 attached hereto have the meanings
described in the Credit Agreement.

    Schedule 1 attached hereto sets forth, as of the date hereof, the financial
data and computations evidencing the Borrower's compliance with the covenants
contained in Section 10 of the Credit Agreement (both before and after giving
effect to the borrowings to be made on the date hereof), all of which data and
computations, to the best knowledge and belief of the chief financial officer
executing and delivering this Compliance Certificate on behalf of the Borrower
(the "Chief Financial Officer"), are true, complete and correct.

    The Chief Financial Officer certifies that he is authorized to execute and
deliver this Compliance Certificate on behalf of the Borrower.

    WITNESS our hands this ____ day of ___________________, 200_.

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP, for itself and as agent for
                                 each other Borrower

                                 By:  Boston Properties, Inc., its
                                      general partner

                                 By:
                                    -----------------------------------------
                                       Title:  Chief Financial Officer

                                      C-7-1
<Page>

                                    EXHIBIT D

                (Exhibit D consists of Exhibits D-1 through D-4)

                                                                     EXHIBIT D-1

                              FORM OF BID RATE NOTE

$___________________                                Date: ______________,  20__

    FOR VALUE RECEIVED, the undersigned Boston Properties Limited Partnership, a
Delaware limited partnership, and each of the other undersigned parties and
other parties who are or from time to time become a Borrower under (and as
defined in) the Revolving Credit Agreement referred to (and defined) below
(hereinafter, together with their respective successors in title and assigns,
collectively called the "Borrower"), by this promissory note (hereinafter,
called "this Note"), absolutely and unconditionally and jointly and severally
promise to pay to the order of __________________ (hereinafter, together with
its successors in title and assigns, called the "Bank"), the principal sum of
______________________________ Dollars ($________________) on _________________,
20__, such payment to be made as hereinafter provided, and to pay interest on
the principal sum outstanding hereunder from time to time from and after the
date hereof until the said principal sum or the unpaid portion thereof shall
have become due and payable as provided in the Bid Rate Advance Borrowing Notice
dated __________________, 20__ and attached hereto as Exhibit A.

    Capitalized terms used herein without definition shall have the meanings set
forth in the Revolving Credit Agreement.

    The unpaid principal (not at the time overdue) under this Note shall bear
interest at the rate or rates from time to time in effect under the Revolving
Credit Agreement. Accrued interest on the unpaid principal under this Note shall
be payable on the dates specified in the Revolving Credit Agreement.

    On ____________________, 20__, the date of the final maturity of this Note,
there shall become absolutely due and payable by the Borrower hereunder, and the
Borrower hereby promises to pay to the Bank, the balance (if any) of the
principal hereof then remaining unpaid, all of the unpaid interest accrued
hereon and all (if any) other amounts payable on or in respect of this Note or
the indebtedness evidenced hereby.

                                      D-1-1
<Page>

    Each overdue amount (whether of principal, interest or otherwise) payable on
or in respect of this Note or the indebtedness evidenced hereby shall (to the
extent permitted by applicable law) bear interest at the rates and on the terms
provided in the Revolving Credit Agreement. The unpaid interest accrued on each
overdue amount in accordance with the foregoing terms of this paragraph shall
become and be absolutely due and payable by the Borrower to Bank on demand by
the Agent. Interest on each overdue amount will continue to accrue as provided
by the foregoing terms of this paragraph, and will (to the extent permitted by
applicable law) be compounded daily until the obligations of the Borrower in
respect of the payment of such overdue amount shall be discharged (whether
before or after judgment).

    Each payment of principal, interest or other sum payable on or in respect of
this Note or the indebtedness evidenced hereby shall be made by the Borrower
directly to the Agent in Dollars, for the account of the Bank, at the Agent's
Head Office, on the due date of such payment, and in immediately available and
freely transferable funds. All payments on or in respect of this Note or the
indebtedness evidenced hereby shall be made without set-off or counterclaim and
free and clear of and without any deductions, withholdings, restrictions or
conditions of any nature.

    This Note is made and delivered by the Borrower to the Bank pursuant to a
Third Amended and Restated Revolving Credit Agreement, dated as of January ___,
2003, among (i) the Borrower, (ii) the Banks party thereto (including the Bank)
and (iii) the Agent (hereinafter, as originally executed, and as varied,
supplemented, amended and/or restated, called the "Revolving Credit Agreement").
This Note evidences the obligations of the Borrower (a) to repay the principal
amount of the Bid Rate Loan evidenced hereby; (b) to pay interest, as herein
provided, on the principal amount hereof remaining unpaid from time to time; and
(c) to pay other amounts which may become due and payable hereunder or in
connection herewith pursuant to the Revolving Credit Agreement. Reference is
hereby made to the Revolving Credit Agreement (including the EXHIBITS annexed
thereto) for a complete statement of the terms thereof.

    The Borrower has the right to prepay the unpaid principal of this Note in
full or in part upon the terms contained in the Revolving Credit Agreement. The
Borrower has an obligation to prepay principal of this Note from time to time if
and to the extent required under, and upon the terms contained in, the Revolving
Credit Agreement. Any partial payment of the indebtedness evidenced by this Note
shall be applied in accordance with the terms of the Revolving Credit Agreement.

    Pursuant to and upon the terms contained in Section 14 of the Revolving
Credit Agreement, the entire unpaid principal of this Note, all of the interest
accrued on the unpaid principal of this Note and all (if any) other amounts
payable on or in respect of this Note or the indebtedness evidenced hereby may
be declared to be immediately due and payable, whereupon the entire unpaid
principal of this Note, all of the interest accrued on the unpaid principal of
this Note and all (if any) other amounts payable on or in

                                      D-1-2
<Page>

respect of this Note or the indebtedness evidenced hereby shall (if not already
due and payable) forthwith become and be, or the same may, as provided in said
Section 14, automatically become, due and payable to the Bank without
presentment, demand, protest or any other formalities of any kind, all of which
are hereby expressly and irrevocably waived by the Borrower, excepting only for
notice expressly provided for in the Revolving Credit Agreement.

    All computations of interest payable as provided in this Note shall be made
by the Agent on the basis of the actual number of days elapsed divided by 360.
The interest rate in effect from time to time shall be determined in accordance
with the terms of the Revolving Credit Agreement and the provisions of Section
2.9 thereof.

    Should all or any part of the indebtedness represented by this Note be
collected by action at law, or in bankruptcy, insolvency, receivership or other
court proceedings, or should this Note be placed in the hands of attorneys for
collection after default, the Borrower hereby promises to pay to the holder of
this Note, upon demand by the holder hereof at any time, in addition to
principal, interest and all (if any) other amounts payable on or in respect of
this Note or the indebtedness evidenced hereby, all court costs and attorneys'
fees and all other collection charges and expenses reasonably incurred or
sustained by the holder of this Note.

    The Borrower hereby irrevocably waives notice of acceptance, presentment,
notice of nonpayment, protest, notice of protest, suit and all other conditions
precedent in connection with the delivery, acceptance, collection and/or
enforcement of this Note, except for notices expressly provided for in the
Revolving Credit Agreement. The Borrower hereby absolutely and irrevocably
consents and submits to the jurisdiction of the Courts of the Commonwealth of
Massachusetts sitting in Suffolk County and of any Federal Court located in the
Eastern District of Massachusetts in connection with any actions or proceedings
brought against the Borrower by the holder hereof arising out of or relating to
this Note. This Note may be executed in any number of counterparts and by each
party on a separate counterpart, each of which when so executed and delivered
shall be an original, and all of which together shall constitute one instrument.

    This Note is intended to take effect as a sealed instrument. This Note and
the obligations of the Borrower hereunder shall be governed by and interpreted
and determined in accordance with the laws of the Commonwealth of Massachusetts.

    Each Borrower shall be jointly and severally liable for the full amount
owing under this Note.

                  [Remainder of page intentionally left blank]

                                      D-1-3
<Page>

    IN WITNESS WHEREOF, this BID RATE NOTE has been duly executed by the
undersigned on the day and in the year first above written in Boston,
Massachusetts.

                                 332 HARTWELL AVENUE, LEXINGTON, MA**

                                 MBZ-LEX TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 WALTHAM OFFICE CENTER, WALTHAM, MA

                                 ZEE EM TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

----------
** The designation of the specific Real Estate Asset or Assets owned by any
signatory to this Agreement or any other Loan Document is for informational
purposes only and does not in any way limit the joint and several liability of
each Borrower, for so long as it is a Borrower, for the Obligations.

                                      D-1-4
<Page>

                                 204 SECOND AVENUE, WALTHAM, MA

                                 WP TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 170 TRACER LANE, WALTHAM, MA

                                 TRACER LANE TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      D-1-5
<Page>

                                 33 HAYDEN AVENUE, LEXINGTON, MA

                                 HAYDEN OFFICE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 92 AND 100 HAYDEN AVENUE, LEXINGTON, MA

                                 92 HAYDEN AVENUE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      D-1-6
<Page>

                                 LEXINGTON OFFICE PARK, 420-430 BEDFORD STREET,
                                 LEXINGTON, MA

                                 ELANDZEE TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 40-46 HARVARD STREET, WESTWOOD, MA

                                 40-46 HARVARD STREET TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      D-1-7
<Page>

                                 17 HARTWELL AVENUE, LEXINGTON, MA

                                 ZEE BEE TRUST II

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 ONE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 ONE CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      D-1-8
<Page>

                                 THREE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 THREE CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 ELEVEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 ELEVEN CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                      D-1-9
<Page>

                                 FOURTEEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                 FOURTEEN CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 500 E STREET, S.W., WASHINGTON, D.C.

                                 SCHOOL STREET ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its sole general
                                      partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                     D-1-10
<Page>

                                 LONG WHARF MARRIOTT, BOSTON, MA

                                 DOWNTOWN BOSTON PROPERTIES TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 CAMBRIDGE CENTER MARRIOTT, CAMBRIDGE, MA

                                 TWO CAMBRIDGE CENTER TRUST

                                 By:  Boston Properties Limited Partnership,
                                      its beneficiary

                                      By:  Boston Properties, Inc., its
                                           general partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                     D-1-11
<Page>

                                 DECOVERLY TWO, ROCKVILLE, MD

                                 DECOVERLY TWO LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its Managing Member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 THE CANDLER BUILDING, 111 MARKET PLACE,
                                 BALTIMORE, MD

                                 CANDLER ASSOCIATES L.L.C.

                                 By:  Boston Properties Limited Partnership,
                                      its managing member

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                     D-1-12
<Page>

                                 104 CARNEGIE CENTER, PRINCETON, NJ

                                 CARNEGIE CENTER ASSOCIATES

                                 By:  Boston Properties Limited Partnership, its
                                      general partner

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 105 CARNEGIE CENTER, PRINCETON, NJ

                                 CARNEGIE CENTER ASSOCIATES

                                 By:  Boston Properties Limited Partnership, its
                                      general partner

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                     D-1-13
<Page>

                                 210 CARNEGIE CENTER, PRINCETON, NJ

                                 210 ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 211 CARNEGIE CENTER, PRINCETON, NJ

                                 211 ASSOCIATES LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                     D-1-14
<Page>

                                 CAMBRIDGE CENTER NORTH GARAGE, CAMBRIDGE, MA

                                 CAMBRIDGE CENTER NORTH TRUST

                                 By:  Boston Properties Limited Partnership, its
                                      beneficiary

                                      By:  Boston Properties, Inc., its general
                                           partner

                                           By: /s/ Douglas T. Linde
                                              ----------------------(SEAL)
                                              Douglas T. Linde
                                              Senior Vice President and
                                              Chief Financial Officer

                                 9509 KEY WEST AVENUE, DECOVERLY SEVEN,
                                 ROCKVILLE, MD

                                 DECOVERLY SEVEN LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                     D-1-15
<Page>

                                 ONE TOWER CENTER, EAST BRUNSWICK, NJ

                                 SCV PARTNERS

                                 By:  BP III LLC, its general partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 201 CARNEGIE CENTER, PRINCETON, NJ

                                 PRINCETON CHILDCARE ASSOCIATES
                                 LIMITED PARTNERSHIP

                                 By:  Boston Properties LLC, its sole general
                                      partner

                                      By:  Boston Properties Limited
                                           Partnership, its managing member

                                           By:  Boston Properties, Inc., its
                                                general partner

                                                By: /s/ Douglas T. Linde
                                                   ----------------------(SEAL)
                                                   Douglas T. Linde
                                                   Senior Vice President and
                                                   Chief Financial Officer

                                 399 PARK AVENUE, NEW YORK, NY

                                 195 WEST STREET, WALTHAM, MA

                                 7435 BOSTON BOULEVARD, BUILDING ONE,
                                 SPRINGFIELD, VA

                                     D-1-16
<Page>

                                 7451 BOSTON BOULEVARD, BUILDING TWO,
                                 SPRINGFIELD, VA

                                 7374 BOSTON BOULEVARD, BUILDING FOUR,
                                 SPRINGFIELD, VA

                                 8000 GRAINGER COURT, BUILDING FIVE,
                                 SPRINGFIELD, VA

                                 7500 BOULEVARD, BUILDING SIX,
                                 SPRINGFIELD, VA

                                 7501 BOSTON BOULEVARD, BUILDING SEVEN,
                                 SPRINGFIELD, VA

                                 7601 BOSTON BOULEVARD, BUILDING EIGHT,
                                 SPRINGFIELD, VA

                                 7375 BOSTON BOULEVARD, BUILDING TEN,
                                 SPRINGFIELD, VA

                                 7300 BOSTON BOULEVARD, BUILDING THIRTEEN,
                                 SPRINGFIELD, VA

                                 8000 CORPORATE COURT, BUILDING ELEVEN,
                                 SPRINGFIELD, VA

                                 38 CABOT BOULEVARD, BUCKS COUNTY, PA

                                 365 HERNDON PARKWAY (SUGARLAND I),
                                 HERNDON, VA

                                 397 HERNDON PARKWAY (SUGARLAND II),
                                 HERNDON, VA

                                 164 LEXINGTON ROAD, BILLERICA, MA

                                 THE ARBORETUM, 12700 SUNRISE VALLEY DRIVE,
                                 RESTON, VA

                                 502 CARNEGIE CENTER, PRINCETON, NJ

                                 RESIDENCE INN, CAMBRIDGE, MA

                                     D-1-17
<Page>

                                 212 CARNEGIE CENTER, PRINCETON, NJ

                                 NEWPORT OFFICE CENTER, QUINCY, MA

                                 ORBITAL SCIENCES - PHASE I, DULLES, VA

                                 DECOVERLY THREE, 15204 OMEGA DRIVE, ROCKVILLE,
                                 MD

                                 7450 BOSTON BOULEVARD, BUILDING THREE,
                                 SPRINGFIELD, VA

                                 200 WEST STREET, WALTHAM, MA

                                 Broad Run Business Park Building E,
                                 MORAN ROAD, LEESBURG VA 20175

                                 BOSTON PROPERTIES LIMITED PARTNERSHIP

                                 By:  Boston Properties, Inc., its sole general
                                      partner

                                      By: /s/ Douglas T. Linde
                                         ------------------------(SEAL)
                                         Douglas T. Linde
                                         Senior Vice President and
                                         Chief Financial Officer

                                     D-1-18
<Page>

                                                                     EXHIBIT D-2

                    FORM OF BID RATE ADVANCE BORROWING NOTICE

                                                           [Date]

To:           Fleet National Bank, as Managing Administrative Agent (the
              "Agent")

From:         Boston Properties Limited Partnership and each other Borrower
              under the Credit Agreement referred to below (collectively, the
              "Borrower")

Re:           Third Amended and Restated Revolving Credit Agreement (as amended,
              the "Credit Agreement") dated as of January __, 2003 among the
              Borrower, the Banks party thereto and the Agent.

    We hereby give notice pursuant to Section 2.9(b)(i) of the Credit Agreement
that we jointly and severally request a Bid Rate Advance as follows:

    1.    The Business Day of the proposed Bid Rate Advance is: ______________,
200_.* -

    2.    This request is for an [Absolute Rate Auction in which the rates of
interest to be offered by the Banks shall be absolute rates per annum] [Indexed
Rate Auction in which the rates of interest to be offered by the Banks shall be
rates per annum at a margin greater or less than the Eurodollar Rate plus the
Applicable Eurodollar Margin].

    3.    The terms of the Bid Rate Advance requested are as follows:

<Table>
<Caption>
          Principal Amount**       Interest Period***          Maturity Date****
          ----------------         ---------------             -------------
          <S>                      <C>                         <C>
          $
</Table>

          [repeat as necessary]

    4.    [Insert special terms, if any]

                                      D-2-1
<Page>

    The undersigned hereby certifies that the following statements are true on
the date hereof, and will be true on the date of the proposed Bid Rate
Borrowing, both before and after giving effect thereto and to the application of
the proceeds therefrom:

    (a)   the aggregate outstanding principal amount of the Revolving Credit
Loans, PLUS the aggregate principal amount of all Bid Rate Loans outstanding,
PLUS the aggregate principal amount of all Swingline Loans outstanding, PLUS the
Maximum Drawing Amount and, without double-counting the portion, if any, of any
Letter of Credit which is drawn and included in the Revolving Credit Loans, all
outstanding Reimbursement Obligations, on today's date excluding the requested
Bid Rate Advance is $__________ and including the requested Bid Rate Advance is
$___________,

    (b)   we will use the proceeds of the requested Bid Rate Loan in accordance
with the provisions of the Credit Agreement,

    (c)   attached hereto is a Compliance Certificate of the Borrower,
substantially in the form of Exhibit C-1 to the Credit Agreement, with
appropriate attachments,

    (d)   no Default or Event of Default has occurred and is continuing or will
result from the making of the requested Bid Rate Advance.

    Terms used herein have the meanings assigned to them in the Credit
Agreement.

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP,
                                 for itself and as agent for each other Borrower

                                 By:  Boston Properties, Inc., its general
                                      partner

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

*    Subject to notice requirements of Section 2.9(b)

**   Amount must be a minimum of $5,000,000 or any larger multiple of $1,000,000

***  1 to 180 days for Absolute Rate Auction
     7 to 180 days for Indexed Rate Auction

**** Must be on or before Maturity Date

                                      D-2-2
<Page>

                                                                     EXHIBIT D-3

                             OFFER OF BID RATE LOAN
                             COMPETITIVE BID NOTICE

FLEET NATIONAL BANK, as Managing Administrative Agent
115 Perimeter Center Place
Suite 500
Atlanta, GA  30346

Attention:  Jeffrey Aycock

Re:       Bid Rate Loan Offer to Boston Properties Limited Partnership and each
          other Borrower under (and as defined in) the Third Amended and
          Restated Revolving Credit Agreement dated as of January __, 2003 (as
          amended, the "CREDIT AGREEMENT")

    In response to the Borrower's Bid Rate Advance Borrowing Notice dated
________, 200_, we hereby make the following Bid Rate Loan offer on the
following terms:

    1.    Offering Bank:___________________

    2.    Person to contact at Offering Bank:_________________

    3.    Business Day of Borrowing: * ---------------------------------

    4.    We hereby offer to make Bid Rate Loan(s) in the following principal
          amounts, for the following periods and at the following rates:

<Table>
<Caption>
Minimum         Maximum
Principal       Principal    Applicable    Competitive         Maturity
 Amount**       Amount**     Period***     Bid Rate****          Date
---------       ---------    ----------    ------------        --------
<S>             <C>          <C>           <C>                 <C>
$               $
</Table>

[repeat as necessary]

    We understand and agree that the offer(s) set forth above, subject to the
satisfaction of the applicable conditions set forth in the Credit Agreement,
irrevocably obligates us to

                                      D-3-1
<Page>

make the Bid Rate Loan(s) for which any offer(s) are accepted in whole or in
part by the Borrower.

    Terms used herein have the meanings assigned thereto in the Credit
Agreement.

                                                Very truly yours,

                                                [NAME OF BANK]

Dated:                                          By:
      ------------                                 --------------------
                                                   Authorized Officer

*   As specified in the related Borrowing Notice.

**  Principal amount offer for each period may not exceed principal amount
    requested. Offers must be made for $5,000,000 or any larger multiple of
    $1,000,000.

*** 1 to 180 days, as specified in the related Borrowing Notice. 7 to 180 days,
    as specified in the related Borrowing Notice.

**** Specify rate of interest per annum (each rounded to the nearest 1/10,000th
     of 1%), and indicate whether it is an absolute rate or indexed rate.

                                      D-3-1
<Page>

                                                                     EXHIBIT D-4

                   FORM OF NOTICE OF BID RATE LOAN ACCEPTANCE

    Re: Third Amended and Restated Revolving Credit Agreement (as amended, the
"Credit Agreement"), dated as of January __, 2003, among BOSTON PROPERTIES
LIMITED PARTNERSHIP and each other Borrower defined therein (collectively, the
"Borrower"), the lenders which are or may become parties thereto, and Fleet
National BANK AS MANAGING ADMINISTRATIVE AGENT.

    We hereby give notice pursuant to Section 2.9(b)(iii) of the Credit
Agreement of our acceptance of the following Bid Rate Loan offer(s):

    1.    Bank:_____________________

    2.    Drawdown Date*:_______________

    3.    In the following principal amounts, for the following periods and at
          the following rates:

<Table>
<Caption>
    Principal                                           Bid Rate Loan
    Amount                    Period(s)                 Interest Rate(s)**
    ------                    ---------                 ------------------
    <S>                       <C>                       <C>
    $____________
    $____________
</Table>

    [Repeat 1, 2 and 3 for each Bank as necessary]

    4.    The aggregate principal amount for each identical period is:

<Table>
<Caption>
                                                                   Aggregate
          Period                                              Principal Amount
          ------                                              ----------------
          <S>                                                        <C>
                                                                     $
                                                                     $
</Table>

     We hereby certify (a) that we will use the proceeds of the requested Bid
Rate Loans in accordance with the provisions of the Credit Agreement, (b) to the
best knowledge and belief of the Chief Financial Officer/Treasurer, both before
and after giving effect to the

                                      D-4-1
<Page>

requested Bid Rate Loans (1) no Default or Event of Default exists on the date
hereof or will exist under the Credit Agreement or any other Loan Document on
the drawdown date of such Loans and (2) after taking into account such requested
Bid Rate Loans, no Default or Event of Default will exist as of the drawdown
date of such Loans, (c) to the best knowledge and belief of the Chief Financial
Officer/Treasurer, each of the representations and warranties of the Borrower
contained in the Credit Agreement, the other Loan Documents or in any document
or instrument delivered pursuant to or in connection with the Credit Agreement
was true as of the date as of which they were made and is also true at and as of
the date hereof and will be true at and as of the time of the making of the
requested Bid Rate Loans, with the same effect as if made at and as of that time
except to the extent that such representations and warranties relate expressly
to an earlier date, and (d) that the undersigned is authorized to execute and
deliver this certificate on behalf of each Borrower.

     Capitalized terms which are used herein without definition and which are
defined in the Credit Agreement shall have the same meanings herein as in the
Credit Agreement.

                               Very truly yours,

                                 BOSTON PROPERTIES LIMITED
                                 PARTNERSHIP,
                                 for itself and as agent for each other Borrower

                                 By:  Boston Properties, Inc., its general
                                      partner

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

*  As specified in the related Borrowing Notice

** Specify rate of interest per annum (each rounded to the nearest 1/1,000th of
   1%) for each applicable period.

                                      D-4-1
<Page>

                                                                       EXHIBIT E

                      BOSTON PROPERTIES LIMITED PARTNERSHIP

                                                                January __, 2003

Fleet National Bank
       individually and as Agent, and the other
       Banks party to the Credit Agreement described below
115 Perimeter Center Place, Suite 500
Atlanta, GA 30346

Attention:   Robert C. Avil, Vice President

       RE:   Closing Certificate under Third Amended and Restated Revolving
             Credit Agreement dated as of January __, 2003 (the "Credit
             Agreement")

Ladies and Gentleman:

     The undersigned hereby certifies to you, in accordance with the provisions
of Section 12.19 of the Credit Agreement, that the representations and
warranties of the undersigned contained in the Credit Agreement and in each
document and instrument executed and delivered by the undersigned pursuant to or
in connection therewith are true as of the date hereof and that each Borrower
has performed and complied with all covenants and other obligations required to
be performed or complied with by it on or prior to the Closing Date (except as
any of the foregoing may have been waived or deferred in writing by the Agent
and the Banks) and that no Default or Event of Default has occurred and is
continuing on the date hereof.

     Unless otherwise defined herein, the terms used in this Closing Certificate
have the meanings described in the Credit Agreement.

                                                        Very truly yours,

                                      BOSTON PROPERTIES LIMITED
                                      PARTNERSHIP, for itself and as agent for
                                      each other Borrower

                                      By:  Boston Properties, Inc.

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

                                       E-1
<Page>

                                       E-2

<Page>

                                                                       EXHIBIT F

                                     FORM OF
                       ASSIGNMENT AND ASSUMPTION AGREEMENT

                               Dated ____________

    Reference is made to the Third Amended and Restated Revolving Credit
Agreement, dated as of January __, 2003 (as amended and in effect from time to
time, the "Agreement"), among Boston Properties Limited Partnership (the
"Borrower"), the banking institutions referred to therein as Banks (the
"Banks"), and Fleet National Bank, as agent (the "Agent") for the Banks.
Capitalized terms used herein and not otherwise defined shall have the meanings
assigned to such terms in the Agreement.

     __________________________________________ (the "Assignor") and
________________________________________________ (the "Assignee") agree as
follows:

    1.    The Assignor hereby sells and assigns to the Assignee, and the
Assignee hereby purchases and assumes from the Assignor, a _% interest in and to
all of the Assignor's rights and obligations under the Agreement as of the
Effective Date, (as hereinafter defined).

    2.    The Assignor (i) represents that as of the date hereof, its Commitment
Percentage (without giving effect to assignments thereof which have not yet
become effective) is _%, the outstanding balance of its Loans (unreduced by any
assignments thereof which have not yet become effective) is $__________ and the
aggregate amount of its Letter of Credit Participations (unreduced by any
assignments thereof which have not yet become effective) is $_______; (ii) makes
no representation or warranty and assumes no responsibility with respect to any
statements, warranties or re representations made in or in connection with the
Agreement, the other Loan Documents or any other instrument or document
furnished pursuant thereto or the execution, legality, validity, enforceability,
genuineness, sufficiency or value of the Agreement, the other Loan Documents or
any other instrument or document furnished pursuant thereto, other than that it
is the legal and beneficial owner of the interest being assigned by it hereunder
and that such interest is free and clear of any adverse claim; (iii) makes no
representation or warranty and assumes no responsibility with respect to the
financial condition of the Borrower or any of its Subsidiaries or subsidiaries
(as defined in the Agreement) or any other person which may be primarily or
secondarily liable in respect of any of the Obligations under the Agreement or
the other Loan Documents or any other instrument or document delivered or
executed pursuant thereto; [and (iv) represents that as of the date hereof there
are no Letters of Credit outstanding].

                                       F-1
<Page>

    3.    The Assignee (i) represents and warrants that it is legally authorized
to enter into this Assignment and Assumption; (ii) confirms that it has received
a copy of the Agreement, together with copies of the most recent financial
statements delivered pursuant to Section Section 7.4 and 8.4 thereof, if any,
and such other documents and information as it has deemed appropriate to make
its own credit analysis and decision to enter into this Assignment and
Assumption; (iii) agrees that it will, independently and without reliance upon
the Assignor, any other Bank or the Agent and based on such documents and
information as it shall deem appropriate at the time, continue to make its own
credit decisions in taking or not taking action under the Agreement; (iv)
confirms that it is an Eligible Assignee; (v) appoints and authorizes the Agent,
and each other Bank who may from time to time be designated as an agent in a
limited specific capacity pursuant to an amendment to the Agreement, to take
such action as agent (and with respect to such other Banks, in such limited
capacity as may be designated) on its behalf and to exercise such powers as are
reasonably incidental thereto pursuant to the terms of the Agreement and the
other Loan Documents; and (vi) agrees that it will perform all the obligations
which by the terms of the Agreement are required to be performed by it as a Bank
in accordance with the terms of the Agreement. The Assignor represents and
warrants that it is legally authorized to enter into this Assignment and
Assumption.

    4.    The effective date for this Assignment and Assumption shall be
____________, 20__ (the "Effective Date"). Following the execution of this
Assignment and Assumption, it will be delivered to the Agent for recording in
the Register by the Agent.

    5.    Upon such acceptance and recording, from and after the Effective Date,
and, in accordance with Section 20.1 of the Agreement, the Agent and the
Borrower shall have approved (or be deemed to have approved) the herein
assignment pursuant to Section 20.1 of the Agreement, and the Assignor shall,
with respect to that portion of its interest under the Agreement assigned
hereunder, relinquish its rights and be released from its obligations under the
Agreement accruing from and after the Effective Date.

    6.    Upon such acceptance and recording, from and after the Effective Date,
the Agent shall make all payments in respect of the interest assigned hereby
(including payments of principal, interest, fees and other amounts) to the
Assignee. The Assignor and Assignee shall make all appropriate adjustments in
payments for periods prior to the Effective Date by the Agent or with respect to
the making of this assignment directly between themselves.

    7.    THIS ASSIGNMENT AND ASSUMPTION SHALL RUN TO THE BENEFIT OF THE
BORROWER, IN ACCORDANCE WITH Section 20.1 OF THE AGREEMENT. THIS ASSIGNMENT AND
ASSUMPTION IS INTENDED TO TAKE EFFECT AS A SEALED INSTRUMENT TO BE GOVERNED BY,
AND

                                       F-2
<Page>

CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS.

    IN WITNESS WHEREOF, intending to be legally bound, each of the undersigned
has caused this Assignment and Assumption to be executed on its behalf by its
officer thereunto duly authorized, as of the date first above written.

                                           [NAME OF ASSIGNOR]

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

                                           [NAME OF ASSIGNEE]

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

                                       F-3
<Page>

                                                                       EXHIBIT G

                            FORM OF JOINDER AGREEMENT

                                                                 _________, 20__

    Reference is made to the Third Amended and Restated Revolving Credit
Agreement, dated as of January __, 2003 (as from time to time amended and in
effect, the "Loan Agreement"), among Boston Properties Limited Partnership,
those other Borrowers listed on Schedule 1 of the Loan Agreement and each other
Borrower (collectively, the "Borrower") which from time to time is a party to
the Loan Agreement, the banking institutions referred to the Loan Agreement as
Banks (collectively, the "Banks"), and Fleet National Bank, as Agent (the
"Agent") for the Banks. Capitalized terms used herein and not otherwise defined
shall have the meanings assigned to such in the Agreement.

    In consideration of and as an inducement to the inclusion of the
Unencumbered Asset identified on EXHIBIT A hereto as a Borrowing Base Property
(the "Additional Borrowing Base Property") by the Banks, __________________ (the
"Additional Borrower"), a_____________________, which is a Wholly-owned
Subsidiary of BPLP, hereby acknowledges and agrees to the terms and conditions
of the Loan Agreement, the Revolving Credit Notes and the other Loan Documents
to which any Borrower is a party, joins in the agreements of the Borrower under
the Loan Agreement, the Revolving Credit Notes and the other Loan Documents to
which any Borrower is a party and agrees that all Obligations of the Borrower
under the Loan Agreement, the Revolving Credit Notes and the other Loan
Documents to which any Borrower is a party shall be the obligations, jointly and
severally, of the Additional Borrower with the same force and effect as if the
Additional Borrower was originally a Borrower under the Loan Agreement and an
original signatory to the Loan Agreement, the Revolving Credit Notes and the
other Loan Documents to which any Borrower is a party.

    The Additional Borrower further agrees that its liability hereunder is
direct and primary and may be enforced by the Banks and the Agent before or
after proceeding against any other Borrower.

    At least five (5) Business Days prior to this Joinder Agreement becoming
effective and the Unencumbered Asset identified in EXHIBIT A hereto becoming a
Borrowing Base Property, the Additional Borrower shall have delivered to the
Agent (with copies to the Agent for each Bank) those documents referred to in
Sections 12.3 through 12.9, 12.12. 12.13, 12.15, 12.17, 12.19, 12.20 and 12.21
of the Loan Agreement

                                       G-1
<Page>

with respect to the Additional Borrower, in each case in form and substance
materially the same as those documents delivered by the Borrower on the Closing
Date. The Additional Borrower agrees that the Agent shall have the right to
visit and inspect the Additional Borrowing Base Property at the Borrower's sole
cost and expense.

    The undersigned represents and warrants to the Agent and the Banks that it
has the complete right, power and authority to execute and deliver this Joinder
Agreement and to perform all of the obligations hereunder and the Obligations
under the Loan Agreement, the Revolving Credit Notes and the other Loan
Documents to which any Borrower is a party. This Joinder Agreement shall be
binding upon the undersigned and its successors and assigns and shall inure to
the benefit of the Banks, the Agent and their respective successors and assigns.

    Executed as a sealed instrument as of the _______ day of ___________, 2000.

                                           [ADDITIONAL BORROWER]

                                           -------------------------------------

                                           Name:
                                                  ------------------------------

                                           Title:
                                                  ------------------------------
ACKNOWLEDGED AND AGREED:

BOSTON PROPERTIES LIMITED PARTNERSHIP,
individually and as agent for each Borrower

By:   Boston Properties, Inc., its sole general partner

      By:  /s/ Douglas T. Linde
          -------------------------(SEAL)
          Douglas T. Linde
          Chief Financial Officer

                                       G-2
<Page>

                         EXHIBIT A TO JOINDER AGREEMENT

                       Additional Borrowing Base Property

** The designation of the specific Real Estate Asset or Assets owned by any
signatory to this Agreement or any other Loan Document is for informational
purposes only and does not in any way limit the joint and several liability of
each Borrower, for so long as it is a Borrower, for the Obligations.

                                      G-3<Page>

                                                                     EXHIBIT 4.1

                         CONSENT OF INDEPENDENT AUDITORS

         We consent to the reference to our firm under the caption
"Experts-Independent Auditors" and to the use of our report dated February 27,
2003 in the Amendment No. 1 to the Registration Statement (No. 333-103373)
and related Prospectus of Claymore Securities Defined Portfolios, Series 143.

                                                      /s/ GRANT THORNTON LLP
                                                          GRANT THORNTON LLP

Chicago, Illinois
February 27, 2003

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