Document:

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             SECOND 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 BRANCH AND GRAND CAYMAN BRANCH
                         PNC BANK, NATIONAL ASSOCIATION
                              THE BANK OF NEW YORK
                         BAYERISCHE HYPO-UND VEREINSBANK
                          KEYBANK NATIONAL ASSOCIATION
                            THE CHASE MANHATTAN BANK
              DRESDNER BANK AG, NEW YORK AND GRAND CAYMAN BRANCHES
                                  CITIZENS BANK
                                   SUMMIT 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

             COMMERZBANK AG, NEW YORK BRANCH AND GRAND CAYMAN BRANCH
                             AS DOCUMENTATION AGENT

                                       and

                         PNC BANK, NATIONAL ASSOCIATION

                              THE BANK OF NEW YORK

               BAYERISCHE HYPO-UND VEREINSBANK AG, NEW YORK BRANCH

                                       and

                          KEYBANK NATIONAL ASSOCIATION,
                                  AS CO-AGENTS

                                      with

                      FLEETBOSTON ROBERTSON STEPHENS INC.,
                             ACTING AS LOAN ARRANGER

                           Dated as of March 31, 2000

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                                TABLE OF CONTENTS

SECTION                                                                   PAGE

SECTION 1.        DEFINITIONS AND RULES OF INTERPRETATION                    2

   Section 1.1.     Definitions                                              2

   Section 1.2.     Rules of Interpretation                                 27

SECTION 2.        THE REVOLVING CREDIT FACILITY                             28

   SECTION 2.1.     Commitment to Lend                                      28

   SECTION 2.2.     The Revolving Credit Notes                              29

   SECTION 2.3.     Interest on Revolving Credit Loans; Fees                30

   SECTION 2.4.     Requests for Revolving Credit Loans                     30

   SECTION 2.5.     Conversion Options                                      32

   SECTION 2.6.     Funds for Revolving Credit Loans                        33

   SECTION 2.7.     Reduction of Commitment                                 34

SECTION 3.        LETTERS OF CREDIT                                         34

   SECTION 3.1.     Letter of Credit Commitments                            34

   SECTION 3.2.     Reimbursement Obligation of the Borrower                35

   SECTION 3.3.     Letter of Credit Payments; Funding of a Loan            36

   SECTION 3.4.     Obligations Absolute                                    37

   SECTION 3.5.     Reliance by Issuer                                      37

   SECTION 3.6.     Letter of Credit Fee                                    38

SECTION 4.        REPAYMENT OF THE REVOLVING CREDIT LOANS                   38

   SECTION 4.1.     Maturity                                                38

                                      -i-
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   SECTION 4.2.     Optional Repayments of Revolving Credit Loans           38

   SECTION 4.3.     Mandatory Repayment of Loans                            39

SECTION 5.        CERTAIN GENERAL PROVISIONS                                39

   SECTION 5.1.     Funds for Payments                                      39

   SECTION 5.2.     Computations                                            40

   SECTION 5.3.     Inability to Determine Eurodollar Rate                  40

   SECTION 5.4.     Illegality                                              40

   SECTION 5.5.     Additional Costs, Etc.                                  41

   SECTION 5.6.     Capital Adequacy                                        42

   SECTION 5.7.     Certificate                                             42

   SECTION 5.8.     Indemnity                                               43

   SECTION 5.9.     Interest on Overdue Amounts                             43

SECTION 6.        RECOURSE OBLIGATIONS                                      43

SECTION 7.        REPRESENTATIONS AND WARRANTIES                            43

   SECTION 7.1.     Authority, Etc.                                         44

   SECTION 7.2.     Governmental Approvals                                  46

   SECTION 7.3.     Title to Properties; Leases                             46

   SECTION 7.4.     Financial Statements                                    46

   SECTION 7.5.     No Material Changes, Etc.                               47

   SECTION 7.6.     Franchises, Patents, Copyrights, Etc.                   47

   SECTION 7.7.     Litigation                                              47

   SECTION 7.8.     No Materially Adverse Contracts, Etc.                   48

                                      -ii-
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   SECTION 7.9.     Compliance With Other Instruments, Laws, Etc.           48

   SECTION 7.10.    Tax Status                                              48

   SECTION 7.11     No Event of Default                                     48

   SECTION 7.12.    Investment Company Acts                                 48

   SECTION 7.13.    Absence of UCC Financing Statements, Etc.               48

   SECTION 7.14.    Absence of Liens                                        49

   SECTION 7.15.    Certain Transactions                                    49

   SECTION 7.16.    Employee Benefit Plans; Multiemployer Plans;
                    Guaranteed Pension Plans                                49

   SECTION 7.17.    Regulations U and X                                     49

   SECTION 7.18.    Environmental Compliance                                49

   SECTION 7.19.    Subsidiaries                                            51

   SECTION 7.20.    Loan Documents                                          51

   SECTION 7.21.    REIT Status                                             51

SECTION 8.        AFFIRMATIVE COVENANTS OF THE BORROWER AND BPI             51

   SECTION 8.1.     Punctual Payment                                        51

   SECTION 8.2.     Maintenance of Office                                   52

   SECTION 8.3.     Records and Accounts                                    52

   SECTION 8.4.     Financial Statements, Certificates and Information      52

   SECTION 8.5.     Notices                                                 55

   SECTION 8.6.     Existence of Borrower;  Maintenance of Properties       57

   SECTION 8.7.     Existence of BPI; Maintenance of REIT Status of BPI;
                    Maintenance of Properties                               58

   SECTION 8.8.     Insurance                                               58

   SECTION 8.9.     Taxes                                                   59

   SECTION 8.10.    Inspection of Properties and Books                      59

                                     -iii-
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   SECTION 8.11.    Compliance with Laws, Contracts, Licenses, and
                    Permits                                                 60

   SECTION 8.12.    Use of Proceeds                                         60

   SECTION 8.13.    Addition of Borrowing Base Property                     60

   SECTION 8.14.    Additional Borrowers; Solvency of Borrowers; Removal
                    of Borrowers                                            60

   SECTION 8.15.    Further Assurances                                      61

   SECTION 8.16.    Interest Rate Protection                                61

   SECTION 8.17.    Environmental Indemnification                           62

   SECTION 8.18.    Response Actions                                        62

   SECTION 8.19.    Environmental Assessments                               62

   SECTION 8.20.    Employee Benefit Plans                                  63

   SECTION 8.21.    No Amendments to Certain Documents                      64

SECTION 9.        CERTAIN NEGATIVE COVENANTS OF THE BORROWER AND
                  BPI                                                       64

   SECTION 9.1.     Restrictions on Liabilities                             64

   SECTION 9.2.     Restrictions on Liens, Etc.                             65

   SECTION 9.3.     Restrictions on Investments                             67

   SECTION 9.4.     Merger, Consolidation and Disposition of Assets;
                    Assets of BPI                                           69

   SECTION 9.5.     Compliance with Environmental Laws                      70

   SECTION 9.6.     Distributions                                           70

   SECTION 9.7.     Hotel Properties                                        71

SECTION 10.       FINANCIAL COVENANTS; COVENANTS REGARDING BORROWING BASE
                  PROPERTIES                                                71

   SECTION 10.1.    Consolidated Total Indebtedness                         71

   SECTION 10.2.    Secured Consolidated Total Indebtedness                 71

                                      -iv-
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   SECTION 10.3.    Debt Service Coverage                                   71

   SECTION 10.4.    Unsecured Consolidated Total Indebtedness               72

   SECTION 10.5.    Net Worth                                               72

   SECTION 10.6.    Borrowing Base Properties                               73

   SECTION 10.7.    Borrowing Base Debt Service Coverage Ratio              74

SECTION 11.       [INTENTIONALLY OMITTED.]                                  74

SECTION 12.       CONDITIONS TO THE FIRST ADVANCE                           74

   SECTION 12.1.    Loan Documents                                          74

   SECTION 12.2.    Certified Copies of Organization Documents              74

   SECTION 12.3.    By-laws; Resolutions                                    74

   SECTION 12.4.    Incumbency Certificate: Authorized Signers              75

   SECTION 12.5.    Title Policies                                          75

   SECTION 12.6.    Certificates of Insurance                               75

   SECTION 12.7.    Hazardous Substance Assessments                         75

   SECTION 12.8.    Opinion of Counsel Concerning Organization and
                    Loan Documents                                          75

   SECTION 12.9.    [Reserved.]                                             75

   SECTION 12.10.  Structural Condition Assurances                          75

   SECTION 12.11.  Financial Analysis of Borrowing Base Properties          76

   SECTION 12.12.  Inspection of Borrowing Base Properties                  76

   SECTION 12.13.  Certifications from Government Officials                 76

   SECTION 12.14.  [Reserved.]                                              76

   SECTION 12.15.  Proceedings and Documents                                76

   SECTION 12.16.  Fees                                                     76

   SECTION 12.17.  Closing Certificate; Compliance Certificate              76

                                      -v-
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   SECTION 12.18.  Partnership Documents                                    77

   SECTION 12.19.  Release Documents                                        77

SECTION 13.       CONDITIONS TO ALL BORROWINGS                              77

   SECTION 13.1.    Representations True; No Event of Default;
                    Compliance Certificate                                  77

   SECTION 13.2.    No Legal Impediment                                     77

   SECTION 13.3.    Governmental Regulation                                 77

SECTION 14.       EVENTS OF DEFAULT; ACCELERATION; ETC.                     78

   SECTION 14.1.    Events of Default and Acceleration                      78

   SECTION 14.2.    Termination of Commitments                              82

   SECTION 14.3.    Remedies                                                83

SECTION 15.       SETOFF                                                    83

SECTION 16.       THE AGENT                                                 83

   SECTION 16.1.    Authorization                                           83

   SECTION 16.2.    Employees and Agents                                    84

   SECTION 16.3.    No Liability                                            84

   SECTION 16.4.    No Representations                                      84

   SECTION 16.5.    Payments                                                85

   SECTION 16.6.    Holders of Revolving Credit Notes                       86

   SECTION 16.7.    Indemnity                                               86

   SECTION 16.8.    Agent as Bank                                           86

   SECTION 16.9.    Notification of Defaults and Events of Default          86

   SECTION 16.10.   Duties in the Case of Enforcement                       86

   SECTION 16.11.   Successor Agent                                         87

                                     -vii-
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   SECTION 16.12.   Notices                                                 87

SECTION 17.       EXPENSES                                                  87

SECTION 18.       INDEMNIFICATION                                           88

SECTION 19.       SURVIVAL OF COVENANTS, ETC.                               89

SECTION 20.       ASSIGNMENT; PARTICIPATIONS; ETC.                          90

   SECTION 20.1.    Conditions to Assignment by Banks.                      90

   SECTION 20.2.    Certain Representations and Warranties;
                    Limitations; Covenants                                  90

   SECTION 20.3.    Register                                                91

   SECTION 20.4.    New Revolving Credit Notes                              91

   SECTION 20.5.    Participations                                          92

   SECTION 20.6.    Pledge by Lender                                        92

   SECTION 20.7.    No Assignment by Borrower                               92

   SECTION 20.8.    Disclosure                                              93

   SECTION 20.9.    Syndication                                             93

SECTION 21.       NOTICES, ETC.                                             93

SECTION 22.       BPLP AS AGENT FOR THE BORROWER                            94

SECTION 23.       GOVERNING LAW; CONSENT TO JURISDICTION AND SERVICE        94

SECTION 24.       HEADINGS                                                  94

SECTION 25.       COUNTERPARTS                                              94

SECTION 26.       ENTIRE AGREEMENT, ETC.                                    95

SECTION 27.       WAIVER OF JURY TRIAL AND CERTAIN DAMAGE CLAIMS            95

                                     -vii-
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SECTION 28.       CONSENTS, AMENDMENTS, WAIVERS, ETC.                       95

SECTION 29.       SEVERABILITY                                              97

                                     -viii-
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EXHIBITS

A        Form of Revolving Credit Note
B        Form of Loan Request
C        Form of Compliance Certificate
D        [Intentionally Omitted.]
E        Form of Closing Certificate
F        Form of Assignment and Assumption Agreement
G        Form of Joinder Agreement

                                      -ix-
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       SCHEDULES TO SECOND 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 7.19       Subsidiaries
Schedule 8.5(b)     Environmental Events
Schedule 9.1(e)     BPI Liabilities
Schedule 9.3        Investments

                                      -x-
<PAGE>

                           SECOND AMENDED AND RESTATED
                           REVOLVING CREDIT AGREEMENT

          This SECOND AMENDED AND RESTATED REVOLVING CREDIT AGREEMENT is made as
of the 31st day of March, 2000, 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, BANK OF AMERICA, N.A. ("B of A"), having an address
at 6610 Rock Ledge Drive, 6th Floor, Bethesda, Maryland 20817; COMMERZBANK AG,
NEW YORK BRANCH AND GRAND CAYMAN BRANCH ("Commerz"), having an address at 2
World Financial Center, New York, New York 10281-1050; PNC BANK, NATIONAL
ASSOCIATION ("PNC"), having an address at One PNC Plaza, 249 Fifth Avenue, Mail
Stop P1-P0PP-19-2, Pittsburgh, Pennsylvania 15222, Attention: Real Estate
Banking; THE BANK OF NEW YORK ("BNY"), having an address at One Wall Street, New
York, New York 10286; BAYERISCHE HYPO- UND VEREINSBANK AG, NEW YORK BRANCH
("Hypo"), having an address at 150 East 42nd Street, New York, New York
10017-4679; KEYBANK NATIONAL ASSOCIATION ("Key"), having an address at 666 Fifth
Avenue, Suite 3706, New York, New York 10103; THE CHASE MANHATTAN BANK
("Chase"), having an address at 380 Madison Avenue, 10th Floor, New York, New
York 10017; DRESDNER BANK AG, NEW YORK AND GRAND CAYMAN BRANCHES ("Dresdner"),
having an address at 75 Wall Street, New York, New York 10005; CITIZENS BANK
("Citizens"), having an address at 28 State Street, Boston, Massachusetts 02109;
and SUMMIT BANK ("Summit"), having an address at Commerce Center, 1800 Chapel
Avenue West, Cherry Hill, New Jersey 08002; 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") and FLEET, as
managing administrative agent for itself and each other Bank; and BANK OF
AMERICA, N.A. as Syndication Agent, COMMERZBANK AG, NEW YORK BRANCH AND GRAND
CAYMAN BRANCH, as Documentation Agent, and PNC BANK, NATIONAL ASSOCIATION, THE
BANK OF NEW YORK, BAYERISCHE HYPO- UND VEREINSBANK AG, NEW YORK BRANCH and
KEYBANK NATIONAL ASSOCIATION, as Co-Agents.

                                      -1-
<PAGE>

                                    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 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 (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.

          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 and BPI have 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 March 31, 2000, 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:

                                      -2-
<PAGE>

          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-five" accounting firm.

          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 hereof, PROVIDED such office (which need not be such successor
Agent's head office) is located in Boston, Massachusetts.

          AGREEMENT. This Second 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.

                                      -3-
<PAGE>

          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 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

                                      -4-
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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 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
upon which such Letter of Credit was issued, LESS 15 basis points.

          APPLICABLE EURODOLLAR MARGIN. For purposes of this Agreement, the
Applicable Eurodollar Margin shall be equal to the percentage determined for
each Rate Period in accordance with the following:

          (i) For the period from the Closing Date through the day after the
date on which the Agent has received the financial statements required to be
delivered pursuant to Section 8.4(b) for the quarter ending March 31, 2000, the
Applicable Eurodollar Margin will equal 1.45%.

          (ii) For any period during which the Consolidated Total Indebtedness
on the last day of a quarter is greater than 60% of the Consolidated Total
Adjusted Asset Value on such last day, the Applicable Eurodollar Margin will
equal 1.7%.

          (iii) For any period during which the Consolidated Total Indebtedness
on the last day of a quarter is greater than 55% but less than or equal to 60%
of the Consolidated Total Adjusted Asset Value on such last day, the Applicable
Eurodollar Margin will equal 1.45%.

          (iv) For any period during which the Consolidated Total Indebtedness
on the last day of a quarter is greater than 45% but less than or equal to 55%
of the Consolidated Total Adjusted Asset Value on such last day, the Applicable
Eurodollar Margin will equal 1.25%.

          (v) For any period during which the Consolidated Total Indebtedness on
the last day of a quarter is greater than 35% but less than or equal to 45% of
the Consolidated Total Adjusted Asset Value on such last day, the Applicable
Eurodollar Margin will equal 1.15%.

                                      -5-
<PAGE>

          (vi) For any period during which the Consolidated Total Indebtedness
on the last day of a quarter is less than or equal to 35% of the Consolidated
Total Adjusted Asset Value on such last day, the Applicable Eurodollar Margin
will equal 1.05%.

For purposes of determining the Applicable Eurodollar Margin, Consolidated Total
Indebtedness and Consolidated Total Adjusted Asset Value will be tested as of
the end of each fiscal quarter of the Borrower, commencing with the fiscal
quarter ending March 31, 2000, based upon the annual or quarterly financial
statements required to be delivered pursuant to Section 8.4(a) or 8.4(b),
respectively, and, for purposes of determining the interest rate applicable to
Eurodollar Rate Loans for any Rate Period hereunder, any interest rate change
shall be effective on the date after the date on which such financial statements
are required to be delivered to the Agent (assuming such financial statements
are timely delivered). The Borrower shall notify the Agent in writing of any
change in the Applicable Eurodollar Margin when it submits the financial
statements upon which such change in the Applicable Eurodollar Margin is based.

          APPLICABLE PRIME RATE MARGIN. For purposes of this Agreement, the
Applicable Prime Rate Margin shall be equal to the percentage determined for
each Rate Period in accordance with the following:

          (i) For the period from the Closing Date through the day after the
date on which the Agent has received the financial statements required to be
delivered pursuant to Section 8.4(b) for the quarter ending March 31, 2000, the
Applicable Prime Rate Margin will equal .50%.

          (ii) For any period during which the Consolidated Total Indebtedness
on the last day of a quarter is greater than 60% of the Consolidated Total
Adjusted Asset Value on such last day, the Applicable Prime Rate Margin will
equal .75%.

          (iii) For any period during which the Consolidated Total Indebtedness
on the last day of a quarter is greater than 55% but less than or equal to 60%
of the Consolidated Total Adjusted Asset Value on such last day, the Applicable
Prime Rate Margin will equal .50%.

          (iv) For any period during which the Consolidated Total Indebtedness
on the last day of a quarter is less than or equal to 55% of the Consolidated
Total Adjusted Asset Value on such last day, the Applicable Prime Rate Margin
will equal 0%.

For purposes of determining the Applicable Prime Rate Margin, Consolidated Total
Indebtedness and Consolidated Total Adjusted Asset Value will be tested as of
the end of each fiscal quarter of the Borrower, commencing with the fiscal
quarter ending March 31, 2000, based upon the annual or quarterly financial
statements required to be delivered pursuant to Section 8.4(a) or 8.4(b),
respectively, and, for purposes of determining the interest rate applicable to
Prime Rate Loans for any Rate Period hereunder, any interest

                                      -6-
<PAGE>

rate change shall be effective on the date after the date on which such
financial statements are required to be delivered to the Agent (assuming such
financial statements are timely delivered). The Borrower shall notify the Agent
in writing of any change in the Applicable Prime Rate Margin when it submits
the financial statements upon which such change in the Applicable Prime Rate
Margin is based.

          APPROVED CONDOMINIUM PROPERTY. A Real Estate Asset which is a
condominium unit and in which the Borrower 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 days after it has received copies of the applicable
condominium documents, the Agent shall be deemed to have approved such
documents).

          ARRANGER. FleetBoston Robertson Stephens 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.

          AVERAGE UNUSED COMMITMENT. For any period of time, the daily average
difference between (i) the Total Commitment in effect for each day during such
period and (ii) the sum of the principal amount of Revolving Credit Loans
outstanding on each day during such period PLUS the Maximum Drawing Amount for
each such day during such period.

          BANKS. Collectively, Fleet, B of A, Commerz, PNC, BNY, Hypo, Key,
Chase, Dresdner, Citizens and Summit 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.

          BORROWER. As defined in the preamble hereto.

                                      -7-
<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 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 (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 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

                                      -8-
<PAGE>

such subtraction being DIVIDED BY the Capitalization Rate; PROVIDED that 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, 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.

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

          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.

          CLOSING DATE. The first date on which all of the conditions set forth
in Section 12 have been satisfied.

                                      -9-
<PAGE>

          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
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 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 the following to the
extent deducted in computing such Consolidated net income for such quarter: (i)
Consolidated Total Interest Expense for such quarter and (ii) real estate
depreciation, amortization and other extraordinary items for such quarter; and
MINUS (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
adjusted to include only the funds actually received in cash by the Borrower and
its Subsidiaries from any Partially-Owned Entity and (ii) for the purposes of
calculating Consolidated Total Adjusted Asset Value only, (a) all interest
income of the Borrower and its Subsidiaries received in connection with any
Mortgages and (b) for the period commencing on the Closing Date and ending on
December 31, 2000, all income of the Borrower and its Subsidiaries received from
the ownership or operation of the Embarcadero Center Property.

          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

                                      -10-
<PAGE>

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) if and to the extent specifically required in Section 10.3, the dividends
and distributions, if any, paid or required to be paid during such quarter on
the Preferred Equity or Preferred Creditor Equity, as applicable, of the
Borrower, BPI or any of their respective Subsidiaries, and excluding, in all
events other than as required by Section 10.3(C) hereof, dividends and
distributions attributable to Preferred Equity which is not also Preferred
Creditor Equity.

          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. 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

                                      -11-
<PAGE>

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 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 NET WORTH. As at 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 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) 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 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).
Notwithstanding the foregoing, with respect to any Partially-Owned Entity, (x)
to the extent that such Partially-Owned Entity is providing solely a completion
guaranty in connection with a construction loan (and the Borrower or any such
Subsidiary has not agreed to be, or otherwise is not liable (by way of guaranty
or otherwise), for the Indebtedness incurred in connection with such
construction loan), Consolidated Total Indebtedness shall only be required to
include the Borrower's or such Subsidiaries' PRO RATA liability under the
Indebtedness relating to such completion guaranty (based on the Borrower's or
such Subsidiaries' percentage equity interest in such Partially-Owned Entity),
and (y) in connection with the liabilities described in clauses (a) and (d)
above, only those liabilities for which the Borrower or its Subsidiaries are, or
have agreed to be, liable (whether by way of their percentage equity interest in
the Partially-Owned Entity or, if greater, by way of guaranty, indemnity for
borrowed money, stop-loss agreement or the like) shall be included in
Consolidated Total Indebtedness. 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

                                      -12-
<PAGE>

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 reserves 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.

          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.

          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 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
$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 $20,000,000 in the aggregate to remediate, PROVIDED that for all such
environmental events that, individually or in the aggregate, in the Borrower's
and the Agent's reasonable judgment will cost in excess of $20,000,000 to
remediate, the Borrower has received an indemnification, in form and substance
satisfactory to Agent, for an amount at least equal to $10,000,000 from a third
party, who, in the reasonable opinion of Agent, is a credit-worthy entity.

                                      -13-
<PAGE>

          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 $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 $10,000,000 in the aggregate to fix, PROVIDED that if, in the
Borrower's and Agent's reasonable opinion, such structural issues will cost in
excess of $10,000,000 in the aggregate to fix, the Borrowing Base Value shall be
reduced by an amount equal to the aggregate of all costs in excess of such
$10,000,000.

          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 $. Dollars in 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 55% 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 Sections 8.4(a) and (b), the Advance Rate
shall be equal to 50%, 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 (or, if applicable under Section 10.7 at such time,
less than 1.5 to 1.0). In no event, however, shall the Eligible Amount be in
excess of $500,000,000.

                                      -14-
<PAGE>

          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 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 Regulation D), if

                                      -15-
<PAGE>

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.

          EURODOLLAR BREAKAGE COSTS. With respect to any Eurodollar Rate Loan to
be prepaid prior to the end of the applicable Interest Period or not drawn 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 borrowed.

                    (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.

                                      -16-
<PAGE>

          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 Agent is offered
Dollar deposits two Eurodollar Business Days prior to the beginning of such
Interest Period in an interbank eurodollar market where the eurodollar and
foreign currency and exchange operations of 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). Revolving Credit Loans bearing interest
calculated by reference to the Eurodollar Rate.

          EVENT OF DEFAULT. See Section 14.1.

          EXCEPTION PROPERTY. See Section 10.6.

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

          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, solely for the period commencing on the Closing Date and ending on
December 31, 2000, the Fair Market Value of Real Estate Assets attributable to
the Embarcadero Center Property shall be an amount equal to $1,254,000,000.

          FINANCIAL STATEMENT DATE. December 31, 1999.

          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.

                                      -17-
<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).

          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 borrowed money whether direct or indirect in respect of indebtedness or
obligations of others.

          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, but no less than quarterly.

          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 last day of the calendar month, 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

                                      -18-
<PAGE>

               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 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.

                                      -19-
<PAGE>

          LEASING COSTS. Collectively, leasing commissions, legal fees, design
costs, tenant improvement costs and other costs incurred by the Borrower, its
Subsidiaries or any Partially-Owned Entity in connection with entering into
Leases or amendments thereto.

          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 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 Revolving Credit Notes, the Joinder
Documents and any and all other agreements, instruments, documents or
certificates now or hereafter evidencing or otherwise relating to the Revolving
Credit 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.

          MAJORITY BANKS. As of any date, the Banks whose aggregate Commitments
constitute at least fifty-one percent (51%) of the Total
Commitment.

                                      -20-
<PAGE>

          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. March 31, 2003, or such earlier date on which the
Revolving Credit Loans shall become due and payable pursuant to the terms
hereof.

          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 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, 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.

          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 Revolving Credit
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

                                      -21-
<PAGE>

Agreement or arising or incurred hereafter, direct or indirect, joint or
several, absolute or contingent, matured or 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, 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.

          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)

                                      -22-
<PAGE>

pursuant to the documents or agreements under which such Preferred Equity was
issued 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. 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 Revolving Credit 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 hereof, and all
extensions, renewals, modifications, amendments, substitutions and replacements
thereof

          RATE PERIOD. The period beginning on the day following delivery to the
Agent of the annual or quarterly financial statements required to be delivered
pursuant to Sections 8.4(a) or (b) and ending two days after the day on which
the next quarterly (or annual, if applicable) financial statements are delivered
to the Agent.

          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,

                                      -23-
<PAGE>

without limitation, the Borrowing Base Properties at such time of reference,
but excluding all leaseholds other than University Place, Cambridge,
Massachusetts and other leaseholds which are subject to ground leases having
an unexpired term of not less than thirty (30) years from the date hereof
(which ground lease unexpired term will include only renewal options
exercisable solely at the ground lessee's option and, if exercisable prior to
the Maturity Date, so exercised). Notwithstanding the foregoing, Real Estate
Assets shall also include each Approved Condominium Property, PROVIDED, HOWEVER,
that 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.

          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 Revolving Credit 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).

          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

                                      -24-
<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.

          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.

          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 the aggregate principal amount of $500,000,000, 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.

          REVOLVING CREDIT NOTE RECORD. A Record with respect to the Revolving
Credit Notes.

          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.

                                      -25-
<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.

          TOTAL COMMITMENT. As of any date, the sum of the then current
Commitments of the Banks, PROVIDED that the Total Commitment shall not at any
time exceed $500,000,000.

          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 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

                                      -26-
<PAGE>

anything contained herein to the contrary, the term Unrestricted Cash and Cash
Equivalents shall not include the Commitments of the Banks to make Loans under
this Agreement.

          UNUSED FACILITY FEE. See Section 2.3(d).

          VALUE OF UNENCUMBERED ASSETS. As at any date of determination, the sum
of (i) the Borrowing Base Value PLUS (ii) Unrestricted Cash and Cash Equivalents
on such date, PLUS (iii) 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 attributable 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.

          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,
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.

                                      -27-
<PAGE>

                    (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 Borrower to the Agent (with copies to
the Agent for each Bank) given in accordance with Section 2.4 hereof, 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 an amount equal to such Bank's Commitment
Percentage MULTIPLIED BY 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, 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 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, 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 of) any Default or Event of Default; it being acknowledged and
agreed that

                                      -28-
<PAGE>

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 hereof 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 shall be required to be
made by any Bank unless (in connection with the initial Revolving Credit Loan or
Letter 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 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 (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 Revolving Credit
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 Bank's Revolving Credit 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 Bank's Revolving Credit 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.

                                      -29-
<PAGE>

          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, an unused
facility fee calculated at the rate of 0.125% per annum on the Average Unused
Commitment during each calendar quarter or portion thereof (the "Unused Facility
Fee"). The Unused 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 from the
               Banks on the proposed Drawdown Date, unless such Completed

                                      -30-
<PAGE>

               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 or Letter of Credit to be made or
                    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 knowledge, if the Borrowing Base Value and the
                    Borrowing Base

                                      -31-
<PAGE>

                    Debt Service Coverage Ratio were to be calculated on the
                    Drawdown Date of any 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 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 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 Rate Loan may be continued as such when
any Default or Event of Default has occurred

                                      -32-
<PAGE>

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 for a
Eurodollar Rate Loan that would create greater than six (6) Eurodollar Rate
Loans outstanding shall be deemed to be a Loan 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 Loan
simultaneously with converting or continuing a 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
Loans, 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. 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 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

                                      -33-
<PAGE>

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 Unused Facility Fee then accrued and unpaid on the amount of
the reduction. No reduction or termination of the Commitments may be reinstated.

          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 $75,000,000 at any one time and (b) the sum of (i) all Reimbursement
Obligations (to the extent, if any, not yet deemed a

                                      -34-
<PAGE>

Revolving Credit Loan pursuant to Section 3.3) and (ii) the amount of all 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 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 below, to

                                      -35-
<PAGE>

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 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 hereof 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 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 above. Notwithstanding anything contained in
Section 3.2 above 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

                                      -36-
<PAGE>

Fronting Bank for the amount of such drawing with funds other than the proceeds
of the 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 Loan of another Type in accordance with Section 2.5. Each Bank shall, in
accordance with Section 2.6, make available such Bank's Commitment Percentage
of such 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 Loan on the date of the 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 the 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

                                      -37-
<PAGE>

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
(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
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, 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 REVOLVING CREDIT LOANS.

          SECTION 4.1. MATURITY. 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 outstanding on such date,
together with any and all accrued and unpaid interest thereon, the unpaid
balance of the Unused Facility Fee accrued through such date, and any and all
other unpaid amounts due under this Agreement, the Revolving Credit 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

                                      -38-
<PAGE>

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 time, at least two
(2) Business Days' prior written notice of any prepayment pursuant to this
Section 4.2 of any 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, 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.

          (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 any such obligation
is imposed upon the Borrower 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

                                      -39-
<PAGE>

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
Revolving Credit Note Record 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 thereof, 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
a Eurodollar Rate Loans then outstanding shall be converted 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. 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

                                      -40-
<PAGE>

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

                    (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

                                      -41-
<PAGE>

                    (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, 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, 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.

          SECTION 5.7. CERTIFICATE. A certificate setting forth any additional
amounts payable pursuant to Sections 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,

                                      -42-
<PAGE>

submitted by any Bank or the Agent to the Borrower, shall be PRIMA FACIE
evidence that such amounts are due and owing.

          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%)
above 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.

          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.

          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.

                                      -43-
<PAGE>

          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, 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.

                                      -44-
<PAGE>

          (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 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.

                                      -45-
<PAGE>

          (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 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 S-11, 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:

                                      -46-
<PAGE>

          The consolidated balance sheet of BPI and its Subsidiaries as of
December 31, 1999, and their related consolidated statements of income, changes
in shareholders' equity and cash flows for the fiscal year then ended, and
setting forth in comparative form the figures as of the end of and for the
previous fiscal year, prepared in accordance with GAAP and accompanied by an
auditor's report prepared without qualification by the Accountants (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 then ended.
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.

          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.

                                      -47-
<PAGE>

          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 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

                                      -48-
<PAGE>

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, 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 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

                                      -49-
<PAGE>

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 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,

                                      -50-
<PAGE>

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.

          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 or December 31, 1999 or from maintaining
such qualification at all times during the term of the Loans.

          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) covenants
and agrees that, so long as any Loan, Letter of Credit or Revolving Credit Note
is outstanding or the Banks have 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

                                      -51-
<PAGE>

amounts provided for in this Agreement and the other Loan Documents, all in
accordance with the terms of this Agreement and the Revolving Credit 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 without
qualification by the Accountants; together with a written statement from such
Accountants to the effect that they have read a copy of this Agreement, and
that, in making the examination necessary to said certification, they have
obtained no knowledge of any Default or Event of Default under Section 9 or
Section 10 or otherwise under the provisions of this Agreement relating to the
financial condition of BPI or any of its Subsidiaries, or of any facts or
circumstances that would cause BPI not to continue to qualify as a REIT for
federal income tax purposes, or, if such Accountants shall have obtained
knowledge of any then existing Default, Event of Default or such facts or
circumstances, they shall make disclosure thereof in such statement (and, at the
Agent's request, the Borrower 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

                                      -52-
<PAGE>

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, at the Agent's request, the Borrower 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;

          (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;

                                      -53-
<PAGE>

          (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 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

                                      -54-
<PAGE>

          (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.

          (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

                                      -55-
<PAGE>

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 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

                                      -56-
<PAGE>

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 $1,000,000.

          (e) ACQUISITION OF REAL ESTATE ASSETS. The Borrower shall notify the
Agent in writing (with copies to the Agent for each Bank) within seven (7) days
of the acquisition of any Real Estate Asset 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 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 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

                                      -57-
<PAGE>

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. The
Borrower will take all reasonable actions to assure that its computer based
systems are able to effectively process data including dates on and after
January 1, 2000 and will notify the Agent of any material risk of any inability
to so process data. Such material risk shall constitute a breach hereunder
except to the extent that such risk would constitute 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)
hereof, 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 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

                                      -58-
<PAGE>

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. 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. The Agent and each Bank agrees to keep any non-public
information delivered or made available by the Borrower to it confidential from
anyone other than persons employed or retained by the Agent or such Bank who are
or are expected to become engaged in evaluating, approving, structuring or
administering the Loans; PROVIDED that nothing herein shall prevent the Agent or
any Bank from disclosing such 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,

                                      -59-
<PAGE>

(vi) in connection with any litigation to which the Agent, any Bank, or their
respective Affiliates 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 auditors, and (ix) to
any actual or proposed participant or Eligible Assignee of all or part of its
rights hereunder.

          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 Revolving Credit 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 this Agreement, the Borrower will use the proceeds of the Loans
solely for working capital and general corporate purposes, including, without
limitation, in connection with the acquisition, rehabilitation and development
of Permitted Properties and the acquisition of Mortgages in accordance with the
provisions of this Agreement.

          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

                                      -60-
<PAGE>

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 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. For any period of time during
which the outstanding balance of the Revolving Credit Loans and Letters of
Credit exceeds $335,000,000 for more than 60 consecutive days, the Borrower
shall, upon the Agent's reasonable written request (each, an "Agent Notice"),
maintain in effect interest rate protection arrangements to reduce the
Borrower's interest rate risk on the amounts in excess of such $335,000,000
balance 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. Notwithstanding the foregoing, Borrower shall be considered to be in
compliance with the requirements set forth above if, within ten (10) days after
Borrower's receipt of Agent's written request, Borrower provides evidence
reasonably satisfactory to Agent of Borrower's intent (together with a proposed
plan) to reduce such outstanding amounts under the Revolving Credit Loans and
Letters of Credit to an amount less than $335,000,000 during the sixty (60) day
period following the date of the Agent's written

                                      -61-
<PAGE>

request. Once obtained, the Borrower shall maintain such arrangements in full
force and effect as provided therein, and shall not, without Unanimous Bank
Approval, modify, terminate, or transfer such arrangements during the period in
which the outstanding balance of the Revolving Credit Loans and Letters of
Credit remains in excess of $335,000,000 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 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 this covenant of
indemnification shall survive the payment of the Loans 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

                                      -62-
<PAGE>

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 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

                                      -63-
<PAGE>

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.

          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 Revolving Credit Note is outstanding or any of the
Banks 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 hereof,

          (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;

                                      -64-
<PAGE>

          (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, 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 of this Agreement.

          Without limiting the foregoing, but subject to the other provisions of
this Agreement (including without limitation Section 10 hereof), 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.

          Notwithstanding anything contained herein to the contrary, the
Borrower will not, and will not permit any Subsidiary to, incur any Indebtedness
for borrowed money in any single transaction which exceeds $50,000,000 in the
aggregate unless the Borrower shall have delivered a compliance certificate in
the form of EXHIBIT C-3 hereto to the Agent evidencing covenant compliance at
the time of delivery of the certificate and on a pro-forma basis after giving
effect to such proposed Indebtedness.

          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

                                      -65-
<PAGE>

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) above;

          (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;

          (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

                                      -66-
<PAGE>

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;

          (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

                                      -67-
<PAGE>

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 hereof;

          (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 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

                                      -68-
<PAGE>

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; and

          (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, 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 hereof which is contained in the August 23,
1999 waiver letter in favor of the Borrower by $1,500,000.

          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

                                      -69-
<PAGE>

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 Sections 10.1
through 10.7 hereof 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 hereof relating to the
removal of a 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 in any single transaction having
a sales price (net of any Indebtedness secured by a Lien on such Real Estate
Assets, if any), in excess of $50,000,000 (collectively and individually, "Sell"
or a "Sale") or grant a Lien to secure Indebtedness (an "Indebtedness Lien") in
any single transaction in an amount in excess of $50,000,000 unless, in each
such event, the Borrower has provided to the Agent (with copies to the Agent for
each Bank) a compliance certificate in the form of EXHIBIT C-4 or EXHIBIT C-6,
as applicable, hereto signed by the chief financial officer, treasurer or
controller of the Borrower, setting forth in reasonable detail computations
evidencing compliance with the covenants contained in Section 10 hereof and
certifying that no Default or Event of Default would exist or occur and be
continuing after giving effect to all such proposed Sales or Indebtedness Liens.

          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

                                      -70-
<PAGE>

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 section (iii) above shall cease to apply with respect to such
monetary default.

          (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 and twenty seven
(127) Real Estate Assets.

          SECTION 10. FINANCIAL COVENANTS; COVENANTS REGARDING BORROWING BASE
PROPERTIES. The Borrower covenants and agrees that, so long as any Loan, Letter
of Credit or Revolving Credit 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 for 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
for 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 for 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 for such quarter.

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

                                      -71-
<PAGE>

                         (A)  the ratio of (i) Consolidated EBITDA for such
                              quarter to (ii) Consolidated Fixed Charges for
                              such quarter (exclusive of any Consolidated Fixed
                              Charges attributable to capitalized interest, as
                              determined in accordance with GAAP, and all
                              dividends and distributions on the Preferred
                              Equity, for such quarter) shall not be less than
                              1.75 to 1.0;

                         (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 capitalized interest, as
                              determined in accordance with GAAP, for such
                              quarter and all dividends and distributions paid
                              or required to be paid in such quarter on the
                              Preferred Creditor Equity) shall not be less than
                              1.50 to 1.0, PROVIDED that at any time when
                              Consolidated Total Indebtedness equals or exceeds
                              55% of Consolidated Total Adjusted Asset Value for
                              any quarter, 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
                              capitalized interest, as determined in accordance
                              with GAAP, for such quarter and all dividends and
                              distributions paid or required to be paid in such
                              quarter on the Preferred Creditor Equity) shall
                              not be less than 1.40 to 1.0; and

                         (C)  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 capitalized interest, as
                              determined in accordance with GAAP, and all
                              dividends and distributions 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. UNSECURED CONSOLIDATED TOTAL INDEBTEDNESS. As at the end
of any fiscal quarter, the Value of Unencumbered Assets for such quarter shall
not be less than 1.75 times the Unsecured Consolidated Total Indebtedness on the
last day of such quarter.

          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) $1,423,937,120 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

                                      -72-
<PAGE>

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 Letters of Credit after giving effect to Loan Requests) to
equal or exceed 55% 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 50% of the aggregate Borrowing Base Value.

          (b) Except for the Exception Property, not more than 15% of the
Borrowing Base Value shall be derived from any single Borrowing Base Property.
One Borrowing Base Property (the "Exception Property") (but not more than one
property), which property can differ from time to time, as designated by
Borrower) can constitute up to 25% of the Borrowing Base Value, PROVIDED that
the Exception Property (i) must be CBD Property, and (ii) may not be a hotel
property.

          (c) For purposes of determining the Borrowing Base Value for this
Section 10.6, 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 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

                                      -73-
<PAGE>

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.

          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 (i) 1.40 to 1.0 with respect
to any quarter for which Consolidated Total Indebtedness on the last day of such
quarter was less than 60% of Consolidated Total Adjusted Asset Value for such
quarter, and (ii) 1.50 to 1.0 with respect to any quarter for which Consolidated
Total Indebtedness on the last day of such quarter was equal to or greater than
60% of Consolidated Total Adjusted Asset Value for such quarter.

          SECTION 11. [Intentionally Omitted.]

          SECTION 12. CONDITIONS TO THE FIRST ADVANCE. The obligations of the
Banks 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
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

                                      -74-
<PAGE>

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. 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 and the Agent in form and substance reasonably
satisfactory to the Banks and the Agent from Goodwin, Procter and Hoar LLP and
Shaw, Pittman, Potts & Trowbridge, 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. The Agent and each of
the Banks shall have received evidence satisfactory to the Agent and each of the
Banks as to the good

                                      -75-
<PAGE>

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 12.13 to such
Bank after the Closing Date.

          SECTION 12.12. INSPECTION OF BORROWING BASE PROPERTIES. 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 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
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

                                      -76-
<PAGE>

EXHIBIT C-7 hereto evidencing compliance with the covenants set forth in
Section 10 hereof 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 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 the Banks
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
CERTIFICATES. 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).

          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

                                      -77-
<PAGE>

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);

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

                         (vi) Section 8.12;

                         (vii) Section 8.13;

                                      -78-
<PAGE>

                         (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 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;

                                      -79-
<PAGE>

          (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, no Event of Default under the Loan Document 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;

          (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 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;

                                      -80-
<PAGE>

          (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
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

                                      -81-
<PAGE>

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 hereof (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 Revolving Credit 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, 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 hereunder shall forthwith terminate and the Banks
shall be relieved of all

                                      -82-
<PAGE>

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 hereunder, and upon such notice
being given such unused portion of such 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 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 Revolving
Credit 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 Revolving Credit 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 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

                                      -83-
<PAGE>

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.

          SECTION 16.4. NO REPRESENTATIONS. The Agent shall not be responsible
for the execution or validity or enforceability of this Agreement, the Revolving
Credit 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 Revolving Credit 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 Revolving Credit 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

                                      -84-
<PAGE>

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 Revolving Credit
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 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.

                                      -85-
<PAGE>

          SECTION 16.6. HOLDERS OF REVOLVING CREDIT NOTES. The Agent may deem
and treat the payee of any Revolving Credit 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
Revolving Credit 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 Revolving Credit 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 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.

                                      -86-
<PAGE>

          SECTION 16.11. SUCCESSOR AGENT. Fleet, or any successor Agent, may
resign as Agent at any time by giving 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 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

                                      -87-
<PAGE>

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 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
payment or satisfaction of payment of amounts owing with respect to the
Revolving Credit Notes.

          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, 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

                                      -88-
<PAGE>

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 hereof, 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 Loan and the
termination of 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 Revolving Credit 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 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 Revolving Credit 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.

                                      -89-
<PAGE>

          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 Revolving Credit 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 hereof, each Bank shall
have at all times an amount of its Commitment of not less than $10,000,000 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 Revolving Credit 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 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.

          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

                                      -90-
<PAGE>

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 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 REVOLVING CREDIT NOTES. Upon its receipt of an
Assignment and Assumption executed by the parties to such assignment, together
with each Revolving Credit 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,

                                      -91-
<PAGE>

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 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 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 Revolving Credit Notes.
Such new Revolving Credit Notes shall provide that they are replacements for
the surrendered Revolving Credit Notes, shall be in an aggregate principal
amount equal to the aggregate principal amount of the surrendered Revolving
Credit Notes, shall be dated the effective date of such Assignment and
Assumption and shall otherwise be in substantially the form of the assigned
Revolving Credit Notes. The surrendered Revolving Credit 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 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.

          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 Revolving Credit 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.

                                      -92-
<PAGE>

          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 hereof.

          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 Revolving Credit 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:

          (a) if to the Borrower or BPI, at Boston Properties, Inc., 800
Boylston Street, Boston, Massachusetts 02199, Attention: Mr. Edward H. Linde,
President and Chief Executive 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 & Hoar LLP, Exchange Place, Boston, Massachusetts 02109,
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

                                      -93-
<PAGE>

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 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.

                                      -94-
<PAGE>

          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
REVOLVING CREDIT 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
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) ACKNOWLEDGE 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"

                                      -95-
<PAGE>

                    costs) or any fees due any Bank hereunder, or permits any
                    prepayment not otherwise permitted hereunder; or

                         (ii) changes the unpaid principal amount of, or the
                    rate of interest on, any Loan; 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; or

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

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

                         (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, hereof, 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 hereof, or

                         (iii) changes the rights, duties or obligations of the
                    Agent specified in Section 16 hereof (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).

                                      -96-
<PAGE>

          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.

                  (Remainder of page intentionally left blank)

                                      -97-
<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: ____________________________
                                    Name:
                                    Title:

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

                                    By: ____________________________
                                    Name:
                                    Title:

                                    COMMERZBANK AG, New York Branch and
                                    Grand Cayman Branch, individually and as
                                    Documentation Agent

                                    By: ____________________________
                                    Name:
                                    Title:

                                    By: ____________________________
                                    Name:
                                    Title:

                                    PNC BANK, NATIONAL ASSOCIATION,
                                    individually and as Co-Agent

                                    By: ____________________________
                                    Name:
                                    Title:

                                      -98-
<PAGE>

                                    THE BANK OF NEW YORK,
                                    individually and as Co-Agent

                                    By: ____________________________
                                    Name:
                                    Title:

                                    BAYERISCHE HYPO-UND VEREINSBANK
                                    AG, New York Branch,
                                    individually and as Co-Agent

                                    By: ____________________________
                                    Name:
                                    Title:

                                    By: ____________________________
                                    Name:
                                    Title:

                                    KEYBANK NATIONAL ASSOCIATION,
                                    individually and as Co-Agent

                                    By: ____________________________
                                    Name:
                                    Title:

                                    THE CHASE MANHATTAN BANK,
                                    individually and as Co-Agent

                                    By: ____________________________
                                    Name:
                                    Title:

                                      -99-
<PAGE>
                                    DRESDNER BANK AG, NEW YORK AND
                                    GRAND CAYMAN BRANCHES

                                    By: ____________________________
                                    Name:
                                    Title:

                                    By: ____________________________
                                    Name:
                                    Title:

                                    CITIZENS BANK

                                    By: ____________________________
                                    Name:
                                    Title:

                                    SUMMIT BANK

                                    By: ____________________________
                                    Name:
                                    Title:

                                     -100-
<PAGE>

                                    32 HARTWELL AVENUE, LEXINGTON, MA*

                                    MBZ-LEX TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                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:___________________(SEAL)
                                                David Gaw
                                                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.

                                     -101-
<PAGE>

                                    204 SECOND AVENUE, WALTHAM, MA

                                    WP TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                    170 TRACER LANE, WALTHAM, MA

                                    TRACER LANE TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                    33 HAYDEN AVENUE, LEXINGTON, MA

                                    HAYDEN OFFICE TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -102-
<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:___________________(SEAL)
                                                David Gaw
                                                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:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -103-
<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:___________________(SEAL)
                                                David Gaw
                                                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:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                    THREE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                    THREE CAMBRIDGE CENTER TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -104-
<PAGE>

                                    ELEVEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                    ELEVEN CAMBRIDGE CENTER TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                    FOURTEEN CAMBRIDGE CENTER, CAMBRIDGE, MA

                                    FOURTEEN CAMBRIDGE CENTER TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -105-
<PAGE>

                                    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:______________(SEAL)
                                                    David Gaw
                                                    Chief Financial Officer

                                     -106-
<PAGE>

                                    1950 STANFORD COURT, BUILDING ONE (MD 1),
                                    LANDOVER, MD

                                    MARYLAND 50 BUILDING I 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:___________________(SEAL)
                                                    David Gaw
                                                    Chief Financial Officer

                                    6201 COLUMBIA PARK ROAD, BUILDING TWO (MD2),
                                    LANDOVER, MD

                                    MARYLAND 50 BUILDING II 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:___________________(SEAL)
                                                     David Gaw
                                                     Chief Financial Officer

                                      -107-
<PAGE>

                                    2000 SOUTH CLUB DRIVE, BUILDING THREE (MD3),
                                    LANDOVER, MD

                                    MARYLAND 50 BUILDING III 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:___________________(SEAL)
                                                     David Gaw
                                                     Chief Financial Officer

                                    LONG WHARF MARRIOTT, BOSTON, MA

                                    DOWNTOWN BOSTON PROPERTIES TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -108-
<PAGE>

                                    CAMBRIDGE CENTER MARRIOTT, CAMBRIDGE, MA

                                    TWO CAMBRIDGE CENTER TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc., its
                                             general partner

                                             By:___________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -109-
<PAGE>

                                    910 CLOPPER ROAD, GAITHERSBURG, MD

                                    TECH PARK 270 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:______________(SEAL)
                                                     David Gaw
                                                     Chief Financial Officer

                                    930 CLOPPER ROAD, GAITHERSBURG, MD

                                    TECH PARK 270 PHASE III 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:______________(SEAL)
                                                    David Gaw
                                                    Chief Financial Officer

                                     -110-
<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:______________(SEAL)
                                                    David Gaw
                                                    Chief Financial Officer

                                    THE CANDLER BUILDING, 111 MARKET PLACE,
                                    BALTIMORE, MD

                                    CANDLER ASSOCIATES L.L.C.

                                    By: Boston Properties, Inc.,
                                        its managing member

                                        By:_____________________(SEAL)
                                           David Gaw
                                           Chief Financial Officer

                                    104 CARNEGIE CENTER, PRINCETON, NJ

                                    CARNEGIE CENTER ASSOCIATES

                                    By: Boston Properties Limited Partnership,
                                        its general partner

                                        By:  Boston Properties, Inc.,
                                             its general partner

                                             By:______________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -111-
<PAGE>

                                    105 CARNEGIE CENTER, PRINCETON, NJ

                                    CARNEGIE CENTER ASSOCIATES

                                    By: Boston Properties Limited Partnership,
                                        its general partner

                                        By:  Boston Properties, Inc.,
                                             its general partner

                                             By:_____________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                    206 CARNEGIE CENTER, PRINCETON, NJ

                                    206 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:___________________(SEAL)
                                                    David Gaw
                                                    Chief Financial Officer

                                     -112-
<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:___________________(SEAL)
                                                    David Gaw
                                                    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:___________________(SEAL)
                                                    David Gaw
                                                    Chief Financial Officer

                                     -113-
<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: __________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                    181 SPRING STREET, LEXINGTON, MA

                                    191 SPRING STREET TRUST

                                    By: Boston Properties Limited Partnership,
                                        its beneficiary

                                        By:  Boston Properties, Inc.,
                                             its general partner

                                             By:____________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -114-
<PAGE>

                                    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:__________________(SEAL)
                                                    David Gaw
                                                    Chief Financial Officer

                                    ONE TOWER CENTER, EAST BRUNSWICK, NJ

                                    SCV PARTNERS

                                    By: Boston Properties Limited Partnership,
                                        a general partner

                                        By:  Boston Properties, Inc.,
                                             its general partner

                                             By:____________________(SEAL)
                                                David Gaw
                                                Chief Financial Officer

                                     -115-
<PAGE>

                                    195 WEST STREET, WALTHAM, MA

                                    25-33 DARTMOUTH STREET, WESTWOOD, 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

                                    7600 BOSTON BOULEVARD, BUILDING NINE,
                                    SPRINGFIELD, VA

                                    7375 BOSTON BOULEVARD, BUILDING TEN,
                                    SPRINGFIELD, VA

                                    8000 CORPORATE COURT, BUILDING ELEVEN,
                                    SPRINGFIELD, VA

                                    7700 BOSTON BOULEVARD, BUILDING TWELVE,
                                    SPRINGFIELD, VA

                                    38 CABOT BOULEVARD, BUCKS COUNTY, PA
                                    2391 WEST WINTON AVENUE, HAYWARD, CA

                                    365 HERNDON PARKWAY (SUGARLAND I),
                                    HERNDON, VA

                                     -116-
<PAGE>

                                    397 HERNDON PARKWAY (SUGARLAND II),
                                    HERNDON, VA

                                    164 LEXINGTON ROAD, BILLERICA, MA
                                    FULLERTON SQUARE, SPRINGFIELD, VA

                                    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

                                    BOSTON PROPERTIES LIMITED PARTNERSHIP

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

                                        By:_________________________(SEAL)
                                           David Gaw
                                           Chief Financial Officer

ACKNOWLEDGED AND AGREED:

BOSTON PROPERTIES, INC.

By:_________________________(SEAL)
      David Gaw
      Chief Financial Officer

                                     -117-
<PAGE>

                                             SCHEDULE 1

                                    MBZ-LEX Trust

                                    ZEE EM Trust II

                                    WP Trust

                                    Tracer Lane Trust

                                    Hayden Office 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

                                    Maryland 50 Building I Associates Limited
                                    Partnership

                                    Maryland 50 Building II Associates Limited
                                    Partnership

                                    Maryland 50 Building III Associates Limited
                                    Partnership

                                    Downtown Boston Properties Trust

                                    Two Cambridge Center Trust

                                    Tech Park 270 Limited Partnership

                                    Tech Park 270 Phase III Limited Partnership

                                    Decoverly Two Limited Partnership

                                    Decoverly Seven Limited Partnership

                                    Candler Associates L.L.C.

                                    SCV Partners Carnegie Center Associates

                                    206 Associates Limited Partnership

                                    210 Associates Limited Partnership

                                    211 Associates Limited Partnership

                                    Cambridge Center North Trust

                                      S1-1-
<PAGE>

                                    191 Spring Street Trust

                                      S1-2-
<PAGE>

                                   SCHEDULE 2
<TABLE>
<CAPTION>

BANK                                   COMMITMENT AMOUNT  COMMITMENT PERCENTAGE

<S>                                      <C>                     <C>
Fleet National Bank                       $82,000,000             16.4%
One Federal Street
Boston, MA 02109

Bank of America, N.A.                     $81,500,000             16.3%
MD2-600-06-14
6610 Rock Ledge Drive
6th Floor
Bethesda, MD  20817

Commerzbank AG, New York                  $81,500,000             16.3%
Branch and Grand Cayman Branch
2 World Financial Center
New York, NY  10281-1050

PNC Bank, National Association            $40,000,000              8%
One PNC Plaza
249 Fifth Avenue
Mail Stop P1-P0PP-19-2
Pittsburgh, PA  15265

The Bank of New York                      $35,000,000              7%
One Wall Street
New York, NY  10286

Bayerische Hypo- Und Vereinsbank          $40,000,000              8%
  AG, New York Branch
150 East 42nd Street
New York, NY  10017-4679

The Chase Manhattan Bank                  $20,000,000              4%
380 Madison Avenue
10th Floor
New York, NY  10017

KeyBank                                   $40,000,000              8%
666 Fifth Avenue
Suite 3706
New York, NY  10103

</TABLE>

                                      S2-1
<PAGE>

<TABLE>

<S>                                      <C>                     <C>
Dresdner Bank AG, New York and            $35,000,000              7%
  Grand Gayman Branches
75 Wall Street
New York, NY  10005

Citizens Bank                             $25,000,000              5%
28 State Street
Boston, MA  02109

Summit Bank                               $20,000,000              4%
Commerce Center
1800 Chapel Avenue West
Cherry Hill, NJ  08002

TOTAL                                    $500,000,000            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

                        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.

                        1950 Stanford Court, Building One (MD 1),
                        Landover, MD

                        6201 Columbia Park Road, Building Two (MD2),
                        Landover, MD

                        2000 South Club Drive, Building Three (MD3),
                        Landover, MD

                        Long Wharf Marriott, Boston, MA

                        Cambridge Center Marriott, Cambridge, MA

                        910 Clopper Road, Gaithersburg, MD

                                      S3-1
<PAGE>

                        930 Clopper Road, Gaithersburg, MD

                        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

                        206 Carnegie Center, Princeton, NJ

                        210 Carnegie Center, Princeton, NJ

                        211 Carnegie Center, Princeton, NJ

                        Cambridge Center North Garage, Cambridge, MA

                        181 Spring Street, Lexington, MA

                        195 West Street, Waltham, MA

                        25-33 Dartmouth Street, Westwood, 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

                                      S3-2
<PAGE>

                        7501 Boston Boulevard, Building Seven,
                        Springfield, VA

                        7601 Boston Boulevard, Building Eight,
                        Springfield, VA

                        7600 Boston Boulevard, Building Nine,
                        Springfield, VA

                        7375 Boston Boulevard, Building Ten,
                        Springfield, VA

                        8000 Corporate Court, Building Eleven,
                        Springfield, VA

                        7700 Boston Boulevard, Building Twelve,
                        Springfield, VA

                        38 Cabot Boulevard, Bucks County, PA

                        2391 West Winton Avenue, Hayward, CA

                        365 Herndon Parkway (Sugarland I),
                        Herndon, VA

                        397 Herndon Parkway (Sugarland II),
                        Herndon, VA

                        164 Lexington Road, Billerica, MA

                        Fullerton Square, Springfield, VA

                        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

                                      S3-3
<PAGE>

                        200 West Street, Waltham, MA

                                      S3-4
<PAGE>

                           [To Be Updated by Borrower]

                                   SCHEDULE 4

                                 CBD PROPERTIES

                                      S3-1
<PAGE>

                                 SCHEDULE 7.1(b)

                            PREFERRED CREDITOR EQUITY

                                     [None.]

                                      S4-1
<PAGE>

                                  SCHEDULE 7.7

                                   LITIGATION

                                      None

                                     S7.7-1
<PAGE>

                                  SCHEDULE 7.19

                                  SUBSIDIARIES

                                     S7.19-1
<PAGE>

                                 SCHEDULE 8.5(b)

                              ENVIRONMENTAL MATTERS

                                    S7.19-1
<PAGE>

                                 SCHEDULE 9.1(e)

                                 BPI LIABILITIES

                                   S9.1(e)-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 promises 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 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 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

                                      A-1
<PAGE>

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 Second Amended and Restated Revolving Credit Agreement, dated as of March
__, 2000, 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, as amended on the date hereof, and as further 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. The payment of the principal of and the interest on this Note and
the payment of all (if any) other amounts as may become due and payable on or in
respect of this Note have been guaranteed. Reference is hereby made to the
Revolving Credit Agreement (including the EXHIBITS annexed thereto and the
Guaranty) for a complete statement of the terms thereof and for a description of
such guaranties.

          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 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.

                                      A-2
<PAGE>

          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.

                                    32 HARTWELL AVENUE, LEXINGTON, MA

                                    MBZ-LEX TRUST

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By:___________________(SEAL)
                                                 David Gaw
                                                 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:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                      A-4
<PAGE>

                                    204 SECOND AVENUE, WALTHAM, MA

                                    WP TRUST

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                    170 TRACER LANE, WALTHAM, MA

                                    TRACER LANE TRUST

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                    33 HAYDEN AVENUE, LEXINGTON, MA

                                    HAYDEN OFFICE TRUST

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                      A-5
<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:___________________(SEAL)
                                                 David Gaw
                                                 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:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                    17 HARTWELL AVENUE, LEXINGTON, MA

                                    ZEE BEE TRUST II

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                      A-6
<PAGE>

                                    ONE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                    ONE CAMBRIDGE CENTER TRUST

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                    THREE CAMBRIDGE CENTER, CAMBRIDGE, MA

                                    THREE CAMBRIDGE CENTER TRUST

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By:___________________(SEAL)
                                                    David Gaw
                                                    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:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                      A-7
<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:___________________(SEAL)
                                                 David Gaw
                                                 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:______________(SEAL)
                                                         David Gaw
                                                         Chief Financial Officer

                                      A-8
<PAGE>

                                    1950 STANFORD COURT, BUILDING ONE (MD 1),
                                    LANDOVER, MD

                                    MARYLAND 50 BUILDING I 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:___________________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer

                                    6201 COLUMBIA PARK ROAD, BUILDING TWO (MD2),
                                    LANDOVER, MD

                                    MARYLAND 50 BUILDING II 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:___________________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer

                                      A-9
<PAGE>

                                    2000 SOUTH CLUB DRIVE, BUILDING THREE (MD3),
                                    LANDOVER, MD

                                    MARYLAND 50 BUILDING III 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:___________________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer

                                    LONG WHARF MARRIOTT, BOSTON, MA

                                    DOWNTOWN BOSTON PROPERTIES TRUST

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc., its
                                              general partner

                                              By:___________________(SEAL)
                                                 David Gaw
                                                 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:___________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                      A-10
<PAGE>

                                    910 CLOPPER ROAD, GAITHERSBURG, MD

                                    TECH PARK 270 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:______________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer

                                    930 CLOPPER ROAD, GAITHERSBURG, MD

                                    TECH PARK 270 PHASE III 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:______________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer

                                    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:______________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer
                                      A-11
<PAGE>

                                    THE CANDLER BUILDING, 111 MARKET PLACE,
                                    BALTIMORE, MD

                                    CANDLER ASSOCIATES L.L.C.

                                    By:  Boston Properties, Inc.,
                                         its managing member

                                         By:_____________________(SEAL)
                                            David Gaw
                                            Chief Financial Officer

                                    104 CARNEGIE CENTER, PRINCETON, NJ

                                    CARNEGIE CENTER ASSOCIATES

                                    By:  Boston Properties Limited Partnership,
                                         its general partner

                                         By:  Boston Properties, Inc.,
                                              its general partner

                                              By:______________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                      A-12
<PAGE>

                                    105 CARNEGIE CENTER, PRINCETON, NJ

                                    CARNEGIE CENTER ASSOCIATES

                                    By:  Boston Properties Limited Partnership,
                                         its general partner

                                         By:  Boston Properties, Inc.,
                                              its general partner

                                              By:_____________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                    206 CARNEGIE CENTER, PRINCETON, NJ

                                    206 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:___________________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer

                                      A-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:___________________(SEAL)
                                                      David Gaw
                                                      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:___________________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer

                                    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:  __________________(SEAL)
                                                   David Gaw
                                                   Chief Financial Officer

                                      A-14
<PAGE>

                                    181 SPRING STREET, LEXINGTON, MA

                                    191 SPRING STREET TRUST

                                    By:  Boston Properties Limited Partnership,
                                         its beneficiary

                                         By:  Boston Properties, Inc.,
                                              its general partner

                                              By:____________________(SEAL)
                                                 David Gaw
                                                 Chief Financial Officer

                                    9500 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:__________________(SEAL)
                                                      David Gaw
                                                      Chief Financial Officer

                                    ONE TOWER CENTER, EAST BRUNSWICK, NJ

                                    SCV PARTNERS

                                    By:  Boston Properties Limited Partnership,
                                         a general partner

                                         By:  Boston Properties, Inc.,
                                              its general partner

                                              By:____________________(SEAL)
                                                  David Gaw
                                                  Chief Financial Officer

                                      A-15
<PAGE>

                                    195 WEST STREET, WALTHAM, MA

                                    25-33 DARTMOUTH STREET, WESTWOOD, 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

                                    7600 BOSTON BOULEVARD, BUILDING NINE,
                                    SPRINGFIELD, VA

                                    7375 BOSTON BOULEVARD, BUILDING TEN,
                                    SPRINGFIELD, VA

                                    8000 CORPORATE COURT, BUILDING ELEVEN,
                                    SPRINGFIELD, VA

                                    7700 BOSTON BOULEVARD, BUILDING TWELVE,
                                    SPRINGFIELD, VA

                                    38 CABOT BOULEVARD, BUCKS COUNTY, PA

                                    2391 WEST WINTON AVENUE, HAYWARD, CA

                                    365 HERNDON PARKWAY (SUGARLAND I),
                                    HERNDON, VA

                                      A-16
<PAGE>

                                    397 HERNDON PARKWAY (SUGARLAND II),
                                    HERNDON, VA

                                    164 LEXINGTON ROAD, BILLERICA, MA

                                    FULLERTON SQUARE, SPRINGFIELD, VA

                                    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

                                    BOSTON PROPERTIES LIMITED PARTNERSHIP

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

                                         By:_________________________(SEAL)
                                            David Gaw
                                            Chief Financial Officer

                                      A-17
<PAGE>

                                                                     EXHIBIT B

                                  LOAN REQUEST

          This Loan Request is made pursuant to Section 2.4/Section 2.5 of the
Second Amended and Restated Revolving Credit Agreement dated as of March 31,
2000 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 now or hereafter 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 Loan ($_______________)
   ___ Conversion of Existing Loan ($_______________) (Current Interest Period
          ending on _________, 19__)
   ___ Continuation of Existing Loan ($_______________) (Current Interest Period
          ending on _________, 19__)
   ___ 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 Loan or the date of issue, extension or
   renewal of the Letter of Credit requested in this Loan Request is:

   ___________________, 19__

                                      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 _____________, 19__.

                                              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 3.1.1 and/or Section 13.1 of the Second Amended and Restated
Revolving Credit Agreement dated as of March 31, 2000 among the Borrower, Fleet
National Bank, individually and as Agent, and certain other Banks as provided
therein (as the same may now or hereafter 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 Revolving
Credit 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 Revolving Credit 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 of such Loan or the date of [issue] [extension or renewal] of such
Letter of Credit, and (2) 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 or the 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 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 _______________, 19__

                                          BOSTON PROPERTIES LIMITED
                                          PARTNERSHIP, for itself and as agent
                                          for each other Borrower

                                          By:      Boston Properties, Inc., its
                                                   general partner

                                          By: _______________________________
                                                   Title:

                                     C-1-1
<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 Second Amended and Restated Revolving Credit Agreement dated as of March 31,
2000 among the Borrower, Fleet National Bank, individually and as Agent, and
certain other Banks as provided therein (as the same may now or hereafter 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 19_ (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 this Compliance Certificate on behalf of the Borrower.

                                     C-2-1
<PAGE>

          WITNESS our hands this ____ day of ___________________, 19__.

                                             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

         COMPLIANCE CERTIFICATE OF CHIEF FINANCIAL OFFICER OR TREASURER
                          (Incurrence of Indebtedness)

          The undersigned (the "Borrower") HEREBY CERTIFIES THAT:

          This Compliance Certificate is furnished pursuant to Section 9.1 of
the Second Amended and Restated Revolving Credit Agreement dated as of March 31,
2000 among the Borrower, Fleet National Bank, individually and as Agent, and
certain other Banks as provided therein (as the same may now or hereafter be
amended from time to time, the "Credit Agreement"). The Borrower hereby gives
the Agent notice that the Borrower, BPI or a Subsidiary plans to incur
Indebtedness for borrowed money in a single transaction in an amount in excess
of $50,000,000. 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 Indebtedness for borrowed money, 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 the Subsidiaries have been
reviewed by the Chief Financial Officer/Treasurer and/or by employees or agents
under his/her immediate supervision.

          The Chief Financial Officer/Treasurer certifies that he/she is
authorized to execute and deliver this Compliance Certificate on behalf of the
Borrower, BPI and the Subsidiaries.

          WITNESS our hands this ____ day of ___________, 19__.

                                         BOSTON PROPERTIES LIMITED
                                         PARTNERSHIP, for itself and as agent
                                         for each other Borrower

                                         By:      Boston Properties, Inc., its
                                                  general partner

                                         By: _______________________________
                                                  Title:

                                     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) of the Second Amended and Restated Revolving Credit Agreement dated as of
March 31, 2000 among the Borrower, Fleet National Bank, individually and as
Agent, and certain other Banks as provided therein (as the same may now or
hereafter 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) 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 _______________, 19__.

                                         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 Second Amended and
Restated Revolving Credit Agreement dated as of March 31, 2000 among the
Borrower, Fleet National Bank, individually and as Agent, and certain other
Banks as provided therein (as the same may now or hereafter 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 ____________,2000.

                                         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
          (Disposition of assets other than Borrowing Base Properties)
               (in a single transaction in excess of $50,000,000)

          The undersigned (the "Borrower") HEREBY CERTIFIES THAT:

          This Compliance Certificate is furnished pursuant to Section 9.4(b) of
the Second Amended and Restated Revolving Credit Agreement dated as of March 31,
2000 among the Borrower, Fleet National Bank, individually and as Agent, and
certain other Banks as provided therein (as the same may now or hereafter be
amended from time to time, the "Credit Agreement"). The Borrower hereby gives
the Agent notice of its intention to Sell one or more assets (other than
Borrowing Base Properties) or to grant Indebtedness Lien(s) on one or more
assets (other than Borrowing Base Properties) pursuant to Section 9.4(b) 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 all such proposed Sale(s) or Indebtedness Lien(s) 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, their respective Subsidiaries and
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, no Event of Default has occurred and
is continuing and no Default or Event of Default will occur and be continuing
under any Loan Document after giving effect to all such proposed Sale(s) or
Indebtedness Lien(s). [Based upon such review, the Chief Financial
Officer/Treasurer further certifies, to the best knowledge and belief of the
Chief Financial Officer/Treasurer, that a Default has occurred and is now
continuing, but that giving effect to such proposed Sale(s) or Indebtedness
Lien(s) and the net proceeds thereof, it is anticipated that such Default will
be cured before it has become an Event of Default.]

          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 _______________, 2000.

                                         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 Second Amended and Restated Revolving Credit Agreement dated as of March 31,
2000 among the Borrower, Fleet National Bank, individually and as Agent, and
certain other Banks as provided therein (as the same may now or hereafter 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 ___________________, 2000.

                                         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

                            [Intentionally Omitted.]

                                      D-1
<PAGE>

                                                                   EXHIBIT E

                      BOSTON PROPERTIES LIMITED PARTNERSHIP

                                                              March __, 2000

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 Second Amended and Restated
              Revolving Credit Agreement dated as of March __, 2000
              (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>

                                                               EXHIBIT F

                                     FORM OF
                       ASSIGNMENT AND ASSUMPTION AGREEMENT

                               Dated ____________

          Reference is made to the Second Amended and Restated Revolving Credit
Agreement, dated as of March 31, 2000 (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 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 Sections 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 CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS.

                                      F-2
<PAGE>

         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 Second Amended and Restated Revolving Credit
Agreement, dated as of March 31, 2000 (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 with respect to the Additional Borrower, in each
case in form and substance materially

                                      G-1
<PAGE>

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:_________________________(SEAL)
           David Gaw
           Chief Executive Officer

                                      G-2<PAGE>

                                                                   EXHIBIT 10.21

[CONFIDENTIAL TREATMENT REQUESTED. CONFIDENTIAL PORTIONS OF THIS AGREEMENT HAVE
BEEN REDACTED AND HAVE BEEN SEPARATELY FILED WITH THE COMMISSION.]

                                LICENSE AGREEMENT
                                     BETWEEN
                           HUMAN GENOME SCIENCES, INC.
                                       AND
                               VICAL INCORPORATED

                                FEBRUARY 24, 2000

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>

<S>   <C>                                   <C>
1     BACKGROUND                             1
2     DEFINITIONS                            2
3     GRANTS AND COVENANTS                   7
4     HGS PRODUCTS                          11
5     VICAL PRODUCTS                        13
6     MILESTONES AND ROYALTIES              16
7     TECHNOLOGY TRANSFER                   20
8     PRODUCT DEVELOPMENT                   21
9     CONFIDENTIALITY                       23
10    PATENT PROSECUTION AND LITIGATION     25
11    STATEMENTS AND REMITTANCES            28
12    TERM AND TERMINATION                  29
13    WARRANTIES AND REPRESENTATIONS        31
14    INDEMNIFICATION                       33
15    FORCE MAJEURE                         35
16    DISPUTE RESOLUTION                    35
17    SEPARABILITY                          36
18    ENTIRE AGREEMENT                      36
19    NOTICES                               37
20    ASSIGNMENT AND CHANGE OF CONTROL      38
21    COUNTERPARTS                          38
22    WAIVER                                38
23    INDEPENDENT RELATIONSHIP              39
24    FURTHER ACTIONS                       39
</TABLE>

                                         i
<PAGE>

                                LICENSE AGREEMENT

THIS AGREEMENT ("Agreement"), dated as of the 24th of February 2000 (the
"Effective Date"), is entered into by Human Genome Sciences, Inc. ("HGS"), a
Delaware corporation, having a place of business at 9410 Key West Avenue,
Rockville, Maryland 20850, and Vical Incorporated ("VICAL"), a Delaware
corporation, having a place of business at 9373 Towne Center Drive, San Diego,
California 92121.

1        BACKGROUND

1.1      HGS is in possession of certain human gene sequence information and has
         the ability and desire to develop and commercialize and to have
         developed and commercialized gene therapy products based on that
         sequence information.

1.2      VICAL is in possession of certain gene therapy delivery methods and has
         the ability and desire to develop and commercialize and to have
         developed and commercialized gene therapy products based on those
         delivery methods.

1.3      Vascular Genetics Inc. ("VGI") has an exclusive license from HGS for
         the use of the gene Vascular Endothelial Growth Factor-2 ("VEGF-2") in
         the gene therapy treatment of vascular diseases. HGS holds a
         significant equity interest in VGI.

1.4      HGS, VICAL, and VGI have agreed in an Investment Agreement, dated
         February 24, 2000 (the "Investment Agreement") to undertake a series of
         transactions in which (1) VGI will receive a license from VICAL for the
         use of VICAL's gene therapy delivery methods in conjunction with
         VEGF-2; (2) HGS will receive a license from VICAL for the use of
         certain VICAL technology with respect to certain genes; (3) VICAL will
         receive a license from HGS for the use of certain genes as gene therapy
         products; (4) VICAL will receive an equity interest in VGI, which VGI
         will have certain rights to redeem; and (5) HGS will receive additional
         equity in VGI and will have returned to it by VGI rights to certain
         genes licensed to VGI by HGS.

<PAGE>

1.5      To effect this series of transactions pursuant to the terms and
         conditions of the Investment Agreement, this Agreement is being
         simultaneously executed with (1) a license agreement between VICAL and
         VGI; (2) a second amendment to the license agreement between HGS and
         VGI; (3) certain other agreements, all as set forth in the Investment
         Agreement.

2        DEFINITIONS.

2.1      "AFFILIATE" shall mean any individual or entity directly or indirectly
         controlling, controlled by or under common control with, the specified
         individual or entity. For purposes of this Agreement, the direct or
         indirect ownership of fifty percent (50%) or more of the outstanding
         voting securities of an entity, or the right to receive fifty (50%) or
         more of the profits or earnings of an entity shall be deemed to
         constitute control. Such other relationship as in fact gives such
         individual or entity the power or ability to control the management,
         business and affairs of an entity shall also constitute control.

2.2      "CONFIDENTIAL INFORMATION" shall mean, with respect to a party, all
         information (and all tangible and intangible embodiments thereof),
         which is owned or controlled by such party, is disclosed by such party
         to the other party pursuant to this Agreement and (if disclosed in
         writing or other tangible medium) is marked or identified as
         confidential at the time of disclosure to the receiving party or (if
         otherwise disclosed) is identified as confidential at the time of
         disclosure to the receiving party and described as such in writing
         within thirty (30) days after such disclosure. Notwithstanding the
         foregoing, CONFIDENTIAL INFORMATION of a party shall not include
         information which, and only to the extent, the receiving party can
         establish by written documentation (a) has been publicly known prior to
         disclosure of such information by the disclosing party to the receiving
         party, (b) has become publicly known, without fault on the part of the
         receiving party, subsequent to disclosure of such information by the
         disclosing party to the receiving party, (c) has been received by the
         receiving party at any time from a source, other than the disclosing
         party, rightfully having possession of and the right to disclose such
         information free of confidentiality obligations, (d) has been otherwise
         known by the receiving party free of confidentiality obligations prior
         to disclosure of such information by the disclosing party to the
         receiving party, or (e) has been independently developed by

                                           -2-
<PAGE>

         employees or others on behalf of the receiving party without access to
         or use of such information disclosed by the disclosing party to the
         receiving party.

2.3      "CYTOFECTIN DELIVERY TECHNOLOGY" shall mean all patentable or
         unpatentable inventions, discoveries, technology and information of any
         type whatsoever, including without limitation compositions, methods,
         processes, confidential information, technical information, knowledge,
         experience and know-how regarding the use of cytofectins (including
         cationic lipids) in the delivery of GENES into a patient for the
         treatment or prevention of one or more diseases or conditions; in each
         case which is owned by or licensed to VICAL on the Effective Date or
         during the term of this Agreement, all to the extent and only to the
         extent that VICAL now has or hereafter will have the right to grant
         licenses, immunities or other rights thereunder.

2.4      "DIRECT INJECTION TECHNOLOGY" shall mean all patentable or unpatentable
         inventions, discoveries, technology and information of any type
         whatsoever, including without limitation compositions, methods,
         processes, confidential information, technical information, knowledge,
         experience and know-how regarding the direct injection of GENES
         (including plasmid DNA-based delivery technology) into a patient to
         cause the IN VIVO expression of a desired protein, thereby effecting
         delivery of such protein, to a patient for the treatment or prevention
         of one or more diseases or conditions; in each case which is owned by
         or licensed to VICAL on the Effective Date or during the term of this
         Agreement, all to the extent and only to the extent that VICAL now has
         or will have during the term of this Agreement the right to grant
         licenses, immunities or other rights thereunder.

2.5      "DNA PROCESS TECHNOLOGY" shall mean all patentable or unpatentable
         inventions, discoveries, technology and information of any type
         whatsoever, including without limitation compositions, methods,
         processes, confidential information, technical information, knowledge,
         experience and know-how regarding technologies related to the
         manufacture and processing of plasmid DNA for human use; in each case ,
         which is owned by or licensed to VICAL on the Effective Date or during
         the term of this Agreement, all to the extent and only to the extent
         that VICAL now has or will have during the term of this Agreement the
         right to grant licenses, immunities or other rights

                                   -3-
<PAGE>

         thereunder.

2.6      "EXCLUSIVE HGS PRODUCT" means any product or part thereof (a) the
         manufacture, use or sale of which is covered by an VICAL PATENT or is
         otherwise based on, uses or incorporates the VICAL TECHNOLOGY and (b)
         comprises an HGS RESEARCH GENE as to which HGS has exercised an option
         under Paragraph 3.2 and been granted a license under Paragraph 4.3.

2.7      "EXCLUSIVE VICAL PRODUCT" means any product or part thereof (a) the
         manufacture, use, or sale of which is covered by a HGS PATENT or is
         otherwise based on, uses or incorporates the HGS TECHNOLOGY, and (b)
         comprises a VICAL RESEARCH GENE as to which VICAL has exercised an
         option under Paragraph 3.6 and been granted a license under Paragraph
         5.4.

2.8      "FIELD" shall mean the intervention, treatment and/or prevention of a
         disease or disorder in humans by GENE THERAPY.

2.9      "GENE" shall mean a human nucleotide sequence, including DNA, RNA and
         complementary and reverse complementary nucleotide sequences thereto,
         whether coding or non-coding and whether intact or a fragment.

2.10     "GENE THERAPY" shall mean the treatment or prevention of a disease, or
         remedying a gene deficiency of humans by genetic modification of
         somatic cells (IN VIVO or EX VIVO) with DNA whereby an active
         transcription process results in the expression of a protein or
         oligo(poly)nucleotide encoded by said DNA in a human.

2.11     "HGS DATABASES" shall mean all data and information which during the
         term of this Agreement is owned by HGS or to which HGS has the right to
         grant access, regarding (i) sequence data with respect to genetic
         material (and the corresponding clones) and expression products
         thereof, (ii) information on biological function of such genetic
         material and expression products, and (iii) clones, cell lines and
         vectors.

2.12     "HGS IMPROVEMENTS" shall mean all patentable or unpatentable
         inventions, discoveries, or other technology regarding VICAL RESEARCH
         GENES or the protein(s)

                                      -4-
<PAGE>

         encoded thereby or the use of either of the foregoing, but expressly
         excluding a formulation or combination of a GENE and the delivery
         vehicle for such GENE, made or conceived by VICAL solely or jointly
         with others during the term of this Agreement.

2.13     "HGS PATENT(S)" shall mean (a) all patent applications filed in any
         country before or after the Effective Date; (b) all patents that have
         issued or in the future issue from any of the foregoing patent
         applications, including without limitation, utility and design patents
         and certificates of invention; and (c) all continuations,
         continuations-in-part, divisionals, additions, reissues, renewals,
         re-examinations or extensions, or SPCs to any such patents and patent
         applications; in each case which during the term of this Agreement are
         or become owned by HGS or to which HGS otherwise has, now or in the
         future, the right to grant licenses and which claim in whole or in part
         GENES, HGS TECHNOLOGY or the use thereof in the FIELD.

2.14     "HGS RESEARCH GENE" shall mean a GENE identified by HGS pursuant to
         Paragraph 7.3.

2.15     "HGS TECHNOLOGY" shall mean (a) sequence data with respect to human DNA
         (and the corresponding clones) and expression products, (b) information
         on biological function of GENES, and (c) HGS clones, cell lines and
         vectors and all related information and data which during the term of
         this Agreement, are owned by HGS or to which HGS otherwise has the
         right to grant licenses, immunities or other rights thereunder.

2.16     "IND" shall mean an Investigational New Drug application filed with the
         Food and Drug Administration in the United States, or any similar
         filing with any foreign regulatory authority, to commence human
         clinical testing of a PRODUCT in any country.

2.17     "NET SALES" shall mean, with respect to a PRODUCT, the gross sales
         price invoiced by the seller (calculated on a PRODUCT by PRODUCT basis)
         to THIRD PARTIES that are not (sub)licensees (except as set forth
         below), less normal and customary deductions actually paid or accrued
         by the seller for (i) normal and customary trade, cash and quality
         credits, discounts, refunds or government rebates; (ii) credits for
         claims, allowances or returns; retroactive price reductions;
         chargebacks or the like; and (iii) sales taxes, duties and other
         government charges (including value added tax), but excluding what is

                                      -5-
<PAGE>

         commonly known as income taxes. NET SALES shall not include sales among
         the seller, its (sub)licensees and their respective AFFILIATES for
         resale, provided that NET SALES shall include the amounts invoiced by
         the seller, its sublicensees and their respective AFFILIATES to THIRD
         PARTIES on the resale of such PRODUCT. Sales between or among a party,
         its (sub)licensees and their respective AFFILIATES shall be included
         within NET SALES only if such purchaser is an end-user of such PRODUCT.

2.18     "PRODUCT(S)" shall mean EXCLUSIVE VICAL PRODUCT(S) and EXCLUSIVE HGS
         PRODUCT(S).

2.19     "RESEARCH PLAN" shall mean a plan for research and development of a
         PRODUCT in the FIELD, which includes, at a minimum, scientific data,
         research and development efforts, and research and development
         milestones.

2.20     "RESEARCH TERM" shall mean the period beginning on the Effective Date
         and ending on September 30, 2004.

2.21     "SB" shall mean SmithKline Beecham Corporation and/or SmithKline
         Beecham p.l.c., as defined in the SB/HGS LICENSE AGREEMENT.

2.22     "SB/HGS LICENSE AGREEMENT" shall mean the SB/HGS License Agreement
         dated June 28, 1996 between SmithKline Beecham Corporation, SmithKline
         Beecham p.l.c. and Human Genome Sciences, Inc., as the same may be
         amended from time to time.

2.23     "SP" shall mean Schering Corporation and/or Schering Plough Ltd., as
         defined in the SP/HGS GENE THERAPY LICENSE AGREEMENT.

2.24     "SP/HGS GENE THERAPY LICENSE AGREEMENT" shall mean the Gene Therapy
         Collaboration and License Agreement between HGS and SP, dated June 28,
         1996.

2.25     "SPC" shall mean a right based upon an underlying patent such as a
         Supplementary Protection Certificate.

2.26     "THIRD PARTY" shall mean any party other than HGS or VICAL or an
         AFFILIATE of

                                    -6-
<PAGE>

         VICAL or HGS.

2.27     "VICAL IMPROVEMENTS" shall mean all patentable or unpatentable
         inventions, discoveries or other technology regarding VICAL TECHNOLOGY,
         but expressly excluding a formulation or combination of a GENE and the
         delivery vehicle for such GENE, made or conceived by HGS solely or
         jointly with others during the term of this Agreement, and which
         resulted from the use of VICAL TECHNOLOGY.

2.28     "VICAL PATENT(S)" shall mean (a) all patent applications filed in any
         country before or after the Effective Date; (b) all patents that have
         issued or in the future issue from any of the foregoing patent
         applications, including without limitation, utility and design patents
         and certificates of invention, further including but not limited to
         those patents listed in Appendix A; and (c) all continuations,
         continuations-in-part, divisional, additions, reissues, renewals,
         re-examinations or extensions, or SPCs to any such patents and patent
         applications; in each case which during the term of this Agreement are
         or become owned by VICAL or to which VICAL otherwise has, now or in the
         future, the right to grant licenses and which claim in whole or in part
         VICAL TECHNOLOGY or the use thereof in the FIELD.

2.29     "VICAL RESEARCH GENE" shall mean a GENE identified by VICAL pursuant to
         Paragraph 7.2.

2.30     "VICAL TECHNOLOGY" shall mean (a) DIRECT INJECTION TECHNOLOGY, (b)
         CYTOFECTIN DELIVERY TECHNOLOGY, and (c) DNA PROCESS TECHNOLOGY.

3        GRANTS AND COVENANTS

HGS PRODUCTS

3.1      Subject to the terms and conditions of this Agreement, VICAL grants to
         HGS a non-exclusive, non-transferable, worldwide license (without the
         right to grant sublicenses) under VICAL TECHNOLOGY and VICAL PATENTS to
         perform research and preclinical development in the FIELD during the
         RESEARCH TERM using HGS RESEARCH GENES.

                                    -7-
<PAGE>

3.2      Subject to the terms and conditions of this Agreement, VICAL hereby
         grants to HGS non-exclusive, non-transferable options to obtain
         licenses under Paragraph 3.3 for up to three (3) HGS RESEARCH GENES
         exercisable during the RESEARCH TERM of this Agreement in accordance
         with the provisions of Article 4.

3.3      Subject to the terms and conditions of this Agreement, with respect to
         EXCLUSIVE HGS PRODUCTS directed to an HGS RESEARCH GENE for which HGS
         has exercised an option under Paragraph 3.2 and VICAL is obligated to
         grant a license pursuant to Paragraph 4.3, VICAL grants to HGS an
         exclusive worldwide license (with the right to grant sublicenses) under
         VICAL TECHNOLOGY and VICAL PATENTS to research, develop, make, have
         made, use, import, export, offer to sell and sell such EXCLUSIVE HGS
         PRODUCTS in the FIELD.

3.4      For any sublicense granted by HGS to an AFFILIATE or THIRD PARTY
         pursuant to the provisions of Paragraph 3.3, HGS shall provide VICAL
         with a copy of each sublicense granted hereunder promptly after
         executing the same; provided, however, that HGS shall have the right to
         redact any confidential terms from the copy provided to VICAL. Any such
         sublicense shall be subject and subordinate to the terms and conditions
         of this Agreement, and HGS shall remain responsible for all payments
         due to VICAL.

VICAL PRODUCTS

3.5      Subject to the terms and conditions of this Agreement, HGS grants to
         VICAL a non-exclusive, non-transferable, worldwide license (without the
         right to grant sublicenses), under HGS TECHNOLOGY and HGS PATENTS to
         perform research and preclinical development in the FIELD during the
         RESEARCH TERM using VICAL RESEARCH GENES.

3.6      Subject to the terms and conditions of this Agreement, HGS hereby
         grants to VICAL non-exclusive, non-transferable options to obtain
         licenses under Paragraph 3.7 for up to three (3) VICAL RESEARCH GENES
         exercisable during the RESEARCH TERM of this Agreement in accordance
         with the provisions of Article 5.

3.7      Subject to the terms and conditions of this Agreement, with respect to
         EXCLUSIVE

                                      -8-
<PAGE>

         VICAL PRODUCTS directed to a VICAL RESEARCH GENE for which VICAL has
         exercised an option under Paragraph 3.6 and HGS is obligated to grant
         a license pursuant to Paragraph 5.3, HGS grants to VICAL an exclusive
         worldwide license (with the right to grant sublicenses) under HGS
         TECHNOLOGY and HGS PATENTS to research, develop, make, have made, use,
         import, export, offer to sell and sell such EXCLUSIVE VICAL PRODUCTS
         in the FIELD.

3.8      For any sublicense granted by VICAL to an AFFILIATE or THIRD PARTY
         pursuant to the provisions of Paragraph 3.7, VICAL shall provide HGS
         with a copy of each sublicense granted hereunder promptly after
         executing the same; provided, however, that VICAL shall have the right
         to redact any confidential terms from the copy provided to HGS. Any
         such sublicense shall be subject and subordinate to the terms and
         conditions of this Agreement, and VICAL shall remain responsible for
         all payments due to HGS.

MISCELLANEOUS

3.9      During and after the RESEARCH TERM, VICAL agrees to use HGS TECHNOLOGY
         and HGS PATENTS only as licensed and permitted hereunder. During and
         after the RESEARCH TERM, HGS agrees to use VICAL TECHNOLOGY and VICAL
         PATENTS only as licensed and permitted hereunder.

3.10     The rights and licenses granted to HGS by VICAL are sublicensable
         and/or transferable by HGS to a THIRD PARTY only with respect to a
         specific EXCLUSIVE HGS PRODUCT and only in accordance with the
         provisions of this Agreement. The rights and licenses granted to VICAL
         by HGS are licensable and/or transferable by VICAL to a THIRD PARTY
         only with respect to a specific EXCLUSIVE VICAL PRODUCT and only in
         accordance with the provisions of this Agreement.

3.11     Notwithstanding anything to the contrary in this Agreement, HGS shall
         not grant any rights or license to a THIRD PARTY with respect to an
         EXCLUSIVE HGS PRODUCT unless HGS has first demonstrated IN VIVO
         biological activity for the EXCLUSIVE HGS PRODUCT in a relevant animal
         model. VICAL shall not grant any rights or license to a THIRD PARTY
         with respect to an EXCLUSIVE VICAL PRODUCT unless VICAL has first
         demonstrated IN VIVO biological activity for the EXCLUSIVE VICAL
         PRODUCT in

                                      -9-
<PAGE>

         a relevant animal model. Such evidence of IN VIVO biological activity
         must be statistically different (p < 0.05) from control for at least
         one data point.

3.12     Notwithstanding anything to the contrary herein, HGS shall own all
         right, title and interest in and to the HGS IMPROVEMENTS and all
         intellectual property rights therein and thereto. VICAL hereby
         irrevocably assigns, transfers and conveys to HGS all right, title and
         interest in and to the HGS IMPROVEMENTS and all intellectual property
         rights therein and thereto. VICAL shall take, and shall cause its
         AFFILIATES to take any and all actions and execute and deliver (or
         cause to be executed or delivered) any and all documents reasonably
         requested by HGS, at HGS' expense, in order to effect the foregoing
         assignment.

3.13     HGS hereby grants VICAL a non-exclusive, royalty-free, perpetual,
         worldwide, sublicensable license to HGS IMPROVEMENTS and the claims of
         any HGS PATENT covering such HGS IMPROVEMENTS but only to the extent
         that such claims cover HGS IMPROVEMENTS.

3.14     Notwithstanding anything to the contrary herein, VICAL shall own all
         right, title and interest in and to the VICAL IMPROVEMENTS and all
         intellectual property rights therein and thereto. HGS hereby
         irrevocably assigns, transfers and conveys to VICAL all right, title
         and interest in and to the VICAL IMPROVEMENTS and all intellectual
         property rights therein and thereto. HGS shall take, and shall cause
         its AFFILIATES to take any and all actions and execute and deliver (or
         cause to be executed or delivered) any and all documents reasonably
         requested by VICAL, at VICAL's expense, in order to effect the
         foregoing assignment.

3.15     VICAL hereby grants HGS a non-exclusive, royalty-free, perpetual,
         worldwide, sublicensable license to VICAL IMPROVEMENTS and the claims
         of any VICAL PATENT covering such VICAL IMPROVEMENTS, but only to the
         extent that such claims cover VICAL IMPROVEMENTS.

                                     -10-
<PAGE>

3.16     Notwithstanding anything to the contrary herein, during the period
         commencing upon the Effective Date and ending ***, HGS shall not
         request and VICAL shall not grant to HGS any license rights regarding
         GENES encoding ***.

3.17     No rights, other than those expressly set forth in this Agreement, are
         granted to HGS or VICAL hereunder, and no additional rights shall be
         granted to VICAL or HGS by implication, estoppel or otherwise.

4        HGS PRODUCTS

4.1      If HGS desires to exercise an option under Paragraph 3.2 for an HGS
         RESEARCH GENE, HGS shall do so by submitting to VICAL a written notice
         that describes the HGS RESEARCH GENE for which HGS seeks an exclusive
         license to use VICAL TECHNOLOGY and VICAL PATENTS. Such notice shall
         include the HGS Clone ID Number, the common name of such GENE, the
         amino acid sequence encoded by the GENE, and any other publicly known
         names of the GENE or the amino acid sequence.

4.2      VICAL shall grant an exclusive license pursuant to Paragraph 3.3 to the
         HGS RESEARCH GENE identified in such notice provided that (1) VICAL has
         not previously granted a license to a THIRD PARTY with respect to the
         identified GENE or essentially the same GENE; or (2) VICAL has not
         previously begun an active gene therapy program on such GENE or
         essentially the same gene. For the purposes of this Agreement the term
         "essentially the same" shall mean that the sequence of nucleotides
         comprising the GENE is at least *** homologous to such GENE. In the
         event that VICAL indicates to HGS that VICAL has previously begun a
         program to research and/or develop a product in the FIELD which
         utilizes, comprises, or is based on such GENE or essentially the same
         GENE, within sixty (60) days thereafter HGS shall have the right to
         notify VICAL that HGS at its cost and expense will have an independent
         THIRD PARTY reasonably acceptable to VICAL inspect VICAL's records with
         respect thereto solely for the purpose of verifying that VICAL has
         previously begun such research and development. VICAL

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                     -11-
<PAGE>

         shall permit such independent THIRD PARTY to effect such inspection
         within a reasonable time after such notification provided that such
         THIRD PARTY signs an agreement of confidentiality acceptable to VICAL
         which includes a covenant that the only information which will be
         provided to HGS is whether or not VICAL has in fact begun such research
         and/or development.

4.3      Within thirty (30) days after receipt of a notice pursuant Paragraph
         4.1, VICAL shall notify HGS in writing if VICAL does not have the right
         to grant HGS the license under Paragraph 3.3 for such GENE. Unless
         VICAL timely notifies HGS in writing that it does not have such a
         right, VICAL hereby grants to HGS the exclusive license under Paragraph
         3.3 for EXCLUSIVE HGS PRODUCTS directed to such GENE.

4.4      Following a grant to HGS under Paragraph 4.3 above, HGS shall not
         exercise its option for its second or third GENE, as the case may be,
         until the earlier of (a) the date on which HGS has granted to VICAL the
         first or second, as the case may be, exclusive license pursuant to
         Paragraph 3.7 for a GENE; or (b) the date *** after the date on which
         VICAL has granted to HGS its immediately preceding exclusive license
         pursuant to Paragraph 3.3 (the "HGS Holding Period"); provided,
         however, if VICAL receives written notice pursuant to Paragraph 5.2 or
         5.4 that a GENE requested by VICAL is not available, the HGS Holding
         Period shall continue until the later of (i) the expiration of the ***
         described in clause (b) above, and (ii) the earlier of (A) the date ***
         after the date on which VICAL receives the latest written notice from
         HGS pursuant to Paragraph 5.2 or 5.4, and (B) the date *** after the
         expiration of the *** described in clause (b) above.

4.5      Within thirty (30) days of the grant of each license under Paragraph
         3.3, HGS shall provide VICAL with a RESEARCH PLAN for each HGS RESEARCH
         GENE for which license rights are granted.

4.6      HGS will have the sole responsibility for development and
         commercialization of EXCLUSIVE HGS PRODUCTS.

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                      -12-
<PAGE>

4.7      VICAL agrees not to grant to any THIRD PARTY any rights or licenses in
         or to an EXCLUSIVE HGS PRODUCT or to the use of VICAL TECHNOLOGY or
         VICAL PATENTS with respect to essentially the same GENE which is
         encompassed by such EXCLUSIVE HGS PRODUCT.

4.8      HGS may not exercise an option to obtain an exclusive license under
         Paragraph 3.3 for EXCLUSIVE HGS PRODUCTS directed to more than three
         (3) GENES during the term of this Agreement.

4.9      During the term of this Agreement and for a period of two (2) years
         thereafter, HGS shall keep complete and accurate records of its
         research and development activities conducted under this Agreement
         regarding EXCLUSIVE HGS PRODUCTS and the results thereof. Within thirty
         (30) days after the end of each calendar year during the term of this
         Agreement, HGS shall prepare and provide VICAL with a reasonably
         detailed written report of such activities and results through such
         date.

5        VICAL PRODUCTS

5.1      If VICAL desires to exercise an option under Paragraph 3.6 for a VICAL
         RESEARCH GENE, VICAL may do so by submitting to HGS a written notice
         that describes the GENE for which VICAL seeks an exclusive license.
         Such notice shall include the HGS Clone ID Number, the common name of
         the GENE, the amino acid sequence encoded by the GENE, and any other
         publicly known names of the GENE or the amino acid sequence.

5.2      HGS shall grant an exclusive license pursuant to Paragraph 3.7 to the
         GENE identified in such notice provided that (1) HGS has not previously
         granted a license to a THIRD PARTY with respect to such GENE or
         essentially the same GENE; (2) the GENE is not directed to a
         therapeutic protein that HGS has obtained exclusive rights to pursuant
         to the SB/HGS LICENSE AGREEMENT and similar collaboration agreements;
         (3) HGS has not previously begun an active gene therapy program on the
         GENE or essentially the same GENE; or (4) SP has not exercised its
         option as described in Paragraph 5.3. For the purposes of this
         Agreement the term "essentially the same" shall mean that the sequence

                                      -13-
<PAGE>

         of nucleotides comprising the GENE incorporated in a product for GENE
         THERAPY licensed to a THIRD PARTY, or under development by HGS, is at
         least *** homologous to such GENE. In the event that HGS indicates to
         VICAL that HGS has previously begun a program to research and/or
         develop a product in the FIELD which utilizes, comprises or is based on
         such GENE or essentially the same GENE, within sixty (60) days
         thereafter VICAL shall have the right to notify HGS that VICAL at its
         cost and expense will have an independent THIRD PARTY reasonably
         acceptable to HGS inspect HGS' records with respect thereto solely for
         the purpose of verifying that HGS has previously begun such research
         and development. HGS shall permit such independent THIRD PARTY to
         effect such inspection within a reasonable time after such notification
         provided that such THIRD PARTY signs an agreement of confidentiality
         acceptable to HGS which includes a covenant that the only information
         which will be provided to VICAL is whether or not HGS has in fact begun
         such research and/or development.

5.3      Under the terms of the SP/HGS GENE THERAPY LICENSE AGREEMENT, HGS may
         not license a GENE to VICAL without first notifying SP and offering SP
         the right to license such GENE. SP has the right to exercise its option
         to such GENE within thirty (30) days after such notice from HGS.
         Accordingly, upon written notice from VICAL pursuant to Section 5.1 of
         its intent to exercise its option to a GENE, and if such GENE would
         otherwise be available for licensing to VICAL except for the SP option,
         HGS within ten (10) business days shall notify SP in writing that HGS
         intends to license the GENE to a THIRD PARTY. Such notice shall not
         identify VICAL as the THIRD Party. If SP fails to exercise the option
         within the thirty (30) day period, HGS shall grant an exclusive license
         to VICAL for the EXCLUSIVE VICAL PRODUCT.

5.4      Within ten (10) days after expiration of the SP option period described
         in Paragraph 5.3, HGS shall notify VICAL in writing if HGS does not
         have the right to grant VICAL the license under Paragraph 3.7 for such
         GENE. Unless HGS timely notifies VICAL in writing that it does not have
         such a right, HGS hereby grants to VICAL the exclusive

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                      -14-
<PAGE>

         license under Paragraph 3.7 for EXCLUSIVE VICAL PRODUCTS directed to
         such GENE.

5.5      Following a grant to VICAL under Paragraph 5.4 above, VICAL shall not
         exercise its option for its second or third GENE, as the case may be,
         until the earlier of (a) the date on which VICAL has granted to HGS the
         first or second, as the case may be, exclusive license pursuant to
         Paragraph 3.3 for a GENE; or (b) the date *** after the date on which
         HGS has granted to VICAL its immediately preceding exclusive license
         pursuant to Paragraph 3.7 (the "VICAL Holding Period"); provided,
         however, if HGS receives written notice pursuant to Paragraph 4.2 or
         4.3 that a GENE requested by HGS is not available, the VICAL Holding
         Period shall continue until the later of (i) the expiration of the ***
         described in clause (b) above, and (ii) the earlier of (A) the date ***
         after the date on which HGS receives the latest written notice from
         VICAL pursuant to Paragraph 4.2 or 4.3, and (B) the date *** after the
         expiration of the *** described in clause (b) above.

5.6      Within thirty (30) days of the grant of the license under Paragraph 3.7
         VICAL shall provide HGS with a RESEARCH PLAN for each VICAL RESEARCH
         GENE for which license rights are granted.

5.7      VICAL will have the sole responsibility for development and
         commercialization of EXCLUSIVE VICAL PRODUCTS.

5.8      HGS agrees not to grant to any THIRD PARTY any rights or licenses in or
         to an EXCLUSIVE VICAL PRODUCT or to the use of HGS TECHNOLOGY or HGS
         PATENTS in the FIELD with respect to essentially the same GENE which is
         encompassed by such EXCLUSIVE VICAL PRODUCT.

5.9      VICAL may not exercise an option to obtain an exclusive license under
         Paragraph 3.6 for EXCLUSIVE VICAL PRODUCTS directed to more than three
         (3) GENES during the term of this Agreement.

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                      -15-
<PAGE>

5.10     During the term of this Agreement and for a period of two (2) years
         thereafter, VICAL shall keep complete and accurate records of its
         research and development activities conducted under this Agreement
         regarding EXCLUSIVE VICAL PRODUCTS and the results thereof. Within
         thirty (30) days after the end of each calendar year during the term of
         this Agreement, VICAL shall prepare and provide HGS with a reasonably
         detailed written report of such activities and results through such
         date.

6        MILESTONES AND ROYALTIES

EXCLUSIVE HGS PRODUCT

6.1      Within thirty (30) days of the granting by VICAL of an exclusive
         license for each EXCLUSIVE HGS PRODUCT, HGS shall pay to VICAL the sum
         of ***.

6.2      For the second and third EXCLUSIVE HGS PRODUCTS for which HGS obtains a
         license under Paragraph 3.3, but not for the first such EXCLUSIVE HGS
         PRODUCT, HGS shall pay to VICAL a milestone payment of *** upon start
         of a Phase III clinical trial. Such milestone payment shall be due and
         payable within thirty (30) days after the start of the trial, which for
         the purpose of this Paragraph 6.2 shall be the date the first patient
         is enrolled in the trial. In the event that no Phase III clinical trial
         is initiated prior to submission of an application for regulatory
         approval (e.g., a New Drug Application or a Biological License
         Application) of the PRODUCT, such milestone payment shall be due on the
         date such submission is submitted to the appropriate regulatory
         authority. The milestone payments provided in this Paragraph 6.2 shall
         only be made once for each EXCLUSIVE HGS PRODUCT and shall not be made
         in the case of improvements or modifications such as, but not limited
         to, changed forms, formats, formulations, indications, processes or
         protocols of an EXCLUSIVE HGS PRODUCT for which the payments were
         previously made.

6.3      Subject to Paragraph 6.4, for each EXCLUSIVE HGS PRODUCT, HGS shall pay
         to

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                      -16-
<PAGE>

         VICAL a royalty of *** of NET SALES of the PRODUCT sold by HGS, and its
         (sub)licensees and their respective AFFILIATES.

6.4      Royalty obligations under Paragraph 6.3, with respect to an EXCLUSIVE
         HGS PRODUCT, shall terminate on a country-by-country basis and on an
         EXCLUSIVE HGS PRODUCT by EXCLUSIVE HGS PRODUCT basis on the later of
         (i) *** after first country-wide launch of such PRODUCT in such country
         or (ii) expiration of the last to expire VICAL PATENT licensed to HGS
         under this Agreement which covers the making, having made, importing,
         exporting, offering to sell or using or selling of such PRODUCT in such
         country.

6.5      In the event that HGS licenses an EXCLUSIVE HGS PRODUCT to a THIRD
         PARTY, HGS shall pay VICAL a percentage of all revenues received under
         the license for the EXCLUSIVE HGS PRODUCT, other than revenues received
         as earned royalties, or payments for R&D services provided by HGS to
         the licensee or monies to purchase equity in HGS at fair market value.
         The percentage applied to such payments will vary according to the
         development stage of the PRODUCT at the time such a license agreement
         is entered into, as follows:

         (a)      If such PRODUCT is licensed to a THIRD PARTY prior to the
                  filing of an IND in the United States (or its foreign
                  equivalent in a Major Country), the percentage shall be ***;

         (b)      If such PRODUCT is licensed to a THIRD PARTY after the filing
                  of an IND in the United States (or its foreign equivalent in a
                  Major Country) but before the completion of an initial Phase
                  II(a) clinical trial, the percentage shall be ***;

         (c)      If such PRODUCT is licensed to a THIRD PARTY after completion
                  of an initial Phase II(a) clinical trial, the percentage shall
                  be ***.

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                      -17-
<PAGE>

EXCLUSIVE VICAL PRODUCT

6.6      Within thirty (30) days of the granting by HGS of an exclusive license
         for each EXCLUSIVE VICAL PRODUCT, VICAL shall pay to HGS the sum of
         ***.

6.7      For the second and third EXCLUSIVE VICAL PRODUCTS for which VICAL
         obtains a license under Paragraph 3.7, but not for the first such
         EXCLUSIVE VICAL PRODUCT, VICAL shall pay to HGS a milestone payment ***
         upon start of a Phase III clinical trial. Such milestone payment shall
         be due and payable within thirty (30) days after the start of the
         trial, which for the purpose of this Paragraph shall be the date the
         first patient is enrolled in the trial. In the event that no Phase III
         clinical trial is initiated prior to submission of an application for
         regulatory approval (e.g., a New Drug Application or a Biological
         License Application) of the PRODUCT, such milestone payment shall be
         due on the date such submission is submitted to the appropriate
         regulatory authority. The milestone payments provided in this Paragraph
         6.7 shall only be made once for each EXCLUSIVE VICAL PRODUCT and shall
         not be made in the case of improvements or modifications such as, but
         not limited to, changed forms, formats, formulations, indications,
         processes or protocols of an EXCLUSIVE VICAL PRODUCT for which the
         payments were previously made.

6.8      Subject to Paragraph 6.9, for each EXCLUSIVE VICAL PRODUCT, VICAL shall
         pay to HGS a royalty of *** of NET SALES of the PRODUCT sold by VICAL,
         and its (sub)licensees and their respective AFFILIATES.

6.9      Royalty obligations under Paragraph 6.8, with respect to an EXCLUSIVE
         VICAL PRODUCT, shall terminate on a country-by-country basis and on an
         EXCLUSIVE VICAL PRODUCT by EXCLUSIVE VICAL PRODUCT basis on the later
         of (i) *** after first country-wide launch of such PRODUCT in such
         country or (ii) expiration of the last to expire HGS PATENT licensed to
         VICAL under this Agreement which covers the making, having made,
         importing, exporting, offering to sell or using or selling of such

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                     -18-

<PAGE>

         PRODUCT in such country.

6.10     In the event that VICAL licenses an EXCLUSIVE VICAL PRODUCT to a THIRD
         PARTY, VICAL shall pay HGS a percentage of all revenues received under
         the license for the EXCLUSIVE VICAL PRODUCT, other than revenues
         received as earned royalties, payments for R&D services provided by
         VICAL to the licensee or monies to purchase equity in VICAL at fair
         market value. The percentage applied to such payments will vary
         according to the development stage of the PRODUCT at the time such
         license agreement is entered into, as follows:

         (a)      If such PRODUCT is licensed to a THIRD PARTY prior to the
                  filing of an IND in the United States (or its foreign
                  equivalent in a Major Country), the percentage shall be ***;

         (b)      If such PRODUCT is licensed to a THIRD PARTY after the filing
                  of an IND in the United States (or its foreign equivalent in a
                  Major Country) but before the completion of an initial Phase
                  II(a) clinical trial, the percentage shall be ***;

         (c)      If such PRODUCT is licensed to a THIRD PARTY after completion
                  of an initial Phase II(a) clinical trial, the percentage shall
                  be ***.

MISCELLANEOUS

6.11     For purposes of this Article 6, (a) "Phase II(a) clinical trial" shall
         mean an initial human clinical trial in a Major Country that is
         intended to initially evaluate the effectiveness of a PRODUCT for a
         particular indication or indications in patients with the disease or
         indication under study, or that would otherwise satisfy requirements of
         21 CRF 312.21(b); (b) "Phase III clinical trial" shall mean a human
         clinical trial in a Major Country the results of which could be used as
         pivotal to establish safety and efficacy of a PRODUCT as a basis for a
         marketing approval application submitted to the U.S. FDA or a foreign
         equivalent, or that would otherwise satisfy requirements of 21 CRF
         312.21(c);

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                     -19-
<PAGE>

         and, (c) "Major Country" shall mean the United States, any country in
         the European Union, Canada or Japan.

6.12     If, at the time when any milestone payment listed in the applicable
         Paragraph under this Article 6 with respect to a PRODUCT is due from a
         party, such party has not paid all other milestone payments (if any)
         previously listed in such Paragraph with respect to such PRODUCT, then
         at such time such party shall pay all such unpaid milestone payments
         (if any) previously listed in such Paragraph with respect to such
         PRODUCT. If, at the time of the first commercial sale of a PRODUCT by a
         party, its AFFILIATE or permitted licensee, such party has not paid all
         milestone payments (if any) listed in the applicable Paragraph under
         this Article 6 with respect to such PRODUCT, then at such time such
         party shall pay all such unpaid milestone payments (if any) listed in
         such Paragraph with respect to such PRODUCT.

6.13     The manner in which statements and remittances of royalty and other
         payments are handled is as set forth in Article 11 hereof.

6.14     All payments to be made hereunder shall be by wire transfer of
         immediately available funds to an account designated by VICAL or HGS,
         whoever is to be the recipient of such funds.

7        TECHNOLOGY TRANSFER

7.1      To assist VICAL in the selection of three (3) GENES for exclusive
         licensing pursuant to Paragraph 3.7, HGS scientists shall meet with
         VICAL scientists to discuss therapeutic areas of interest to VICAL and
         to develop criteria and search parameters for potential GENES of
         interest to VICAL. Upon VICAL's request, HGS shall search the HGS
         DATABASES for GENES that meet those criteria and parameters and will
         provide VICAL with a list of the candidates resulting from such
         searches.

7.2      VICAL shall have the right to identify a reasonable number of GENES
         (***) as VICAL

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                     -20-

<PAGE>

         RESEARCH GENES. These genes may be based on the candidates identified
         pursuant to Paragraph 7.1 or may be independently identified by VICAL.
         For each such VICAL RESEARCH GENE, HGS will provide VICAL to the extent
         available all sequence data related to such GENE contained in the HGS
         DATABASES and any HGS clones related to that GENE. HGS will be required
         to furnish such data and clones only to the extent that HGS would be
         able to grant VICAL an EXCLUSIVE LICENSE to such GENE pursuant to
         Paragraph 3.7.

7.3      HGS shall have the right to identify a reasonable number of GENES (***)
         as HGS RESEARCH GENES.

7.4      To assist HGS in the utilization of VICAL TECHNOLOGY, VICAL scientists
         will meet with HGS scientists to discuss the application of VICAL
         TECHNOLOGY to HGS RESEARCH GENES and will provide to HGS any know-how
         or proprietary materials necessary for HGS to use the VICAL TECHNOLOGY
         with respect to an HGS RESEARCH GENE in accordance with the research
         license granted in Paragraph 3.1. VICAL will be required to furnish
         such information only to the extent that VICAL would be able to grant
         HGS an EXCLUSIVE LICENSE to such HGS RESEARCH GENE pursuant to
         Paragraph 3.3.

7.5      Pursuant to Paragraphs 7.1 and 7.4, HGS and VICAL agree to make their
         scientists reasonably available to the other.

8        PRODUCT DEVELOPMENT

8.1      VICAL shall use reasonable efforts to actively research, develop,
         market, promote and sell each royalty bearing EXCLUSIVE VICAL PRODUCT.

8.2      During the term of this Agreement and for a period of five (5) years
         thereafter, VICAL shall keep complete and accurate records of its
         activities conducted under this Agreement regarding the development and
         commercialization of EXCLUSIVE VICAL PRODUCTS

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                     -21-

<PAGE>

         and the results thereof. Within thirty (30) days after the end of each
         calendar year during the term of this Agreement, VICAL shall prepare
         and provide HGS with a reasonably detailed written report of such
         activities and results, through such date.

8.3      If at any time VICAL elects not to continue the development and
         commercialization of an EXCLUSIVE VICAL PRODUCT, or fails to use
         reasonable efforts to actively research, develop, market, promote and
         sell each such PRODUCT as required by Paragraph 8.1, all relevant
         licenses granted by HGS pursuant to this Agreement shall terminate.

8.4      HGS shall use reasonable efforts to actively research, develop, market,
         promote and sell each royalty bearing EXCLUSIVE HGS PRODUCT.

8.5      During the term of this Agreement and for a period of five (5) years
         thereafter, HGS shall keep complete and accurate records of its
         activities conducted under this Agreement regarding the development and
         commercialization of EXCLUSIVE HGS PRODUCTS and the results thereof.
         Within thirty (30) days after the end of each calendar year during the
         term of this Agreement, HGS shall prepare and provide VICAL with a
         reasonably detailed written report of such activities and results,
         through such date.

8.6      If at any time HGS elects not to continue the development and
         commercialization of an EXCLUSIVE HGS PRODUCT, or fails to use
         reasonable efforts to actively research, develop, market, promote and
         sell each such PRODUCT as required by Paragraph 8.4 all relevant
         licenses granted by VICAL pursuant to this Agreement shall terminate;
         provided however, that if HGS is pursuing development and
         commercialization of a gene therapy product not derived from VICAL
         TECHNOLOGY, but directed to the same gene as the EXCLUSIVE HGS PRODUCT,
         HGS shall have the option at its sole discretion to retain the relevant
         VICAL licenses by paying to VICAL the milestones and royalties set
         forth in Paragraph 6.1, on the development and sale of such non-VICAL
         derived product.

                                     -22-

<PAGE>

9        CONFIDENTIALITY

9.1      During the term of this Agreement and for a period of *** following the
         expiration or earlier termination hereof, each party shall maintain in
         confidence the CONFIDENTIAL INFORMATION of the other party, and shall
         not disclose, use or grant the use of the CONFIDENTIAL INFORMATION of
         the other party except on a need-to-know basis to such party's
         AFFILIATES, directors, officers, employees, agents, independent
         contractors and such party's THIRD PARTY licensors of intellectual
         property rights (sub)licensed hereunder, and such party's consultants,
         to the extent such disclosure is reasonably necessary in connection
         with such party's activities as expressly authorized by this Agreement.
         To the extent that disclosure to any person is authorized by this
         Agreement, prior to disclosure, a party shall obtain written agreement
         of such person to hold in confidence and not disclose, use or grant the
         use of the CONFIDENTIAL INFORMATION of the other party except as
         expressly permitted under this Agreement. Each party shall notify the
         other party promptly upon discovery of any unauthorized use or
         disclosure of the other party's CONFIDENTIAL INFORMATION. Upon the
         expiration or earlier termination of this Agreement, each party shall
         return to the other party all tangible items regarding the CONFIDENTIAL
         INFORMATION of the other party and all copies thereof; provided,
         however, that each party shall have the right to retain one (1) copy
         for its legal files for the sole purpose of determining its obligations
         hereunder.

9.2      All confidential information disclosed by one party to the other party
         shall remain the intellectual property of the disclosing party. In the
         event that a court or other legal or administrative tribunal, directly
         or through an appointed master, trustee or receiver, assumes partial or
         complete control over the assets of a party to this Agreement based on
         the insolvency or bankruptcy of such party, the bankrupt or insolvent
         party shall promptly notify the court or other tribunal (i) that
         confidential information received from the other party under this
         Agreement remains the property of the other party and (ii) of the
         confidentiality obligations under this Agreement. In addition, the
         bankrupt or insolvent

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                     -23-

<PAGE>

         party shall, to the extent permitted by law, take all steps necessary
         or desirable to maintain the confidentiality of the other party's
         confidential information and to insure that the court, other tribunal
         or appointee maintains such information in confidence in accordance
         with the terms of this Agreement.

9.3      No public announcement or public disclosure concerning (i) the
         existence of or terms of this Agreement, (ii) research and/or
         discoveries made by one party, (iii) milestones achieved by one party,
         or (iv) exercise by one party of rights and options granted under this
         Agreement, shall be made, either directly or indirectly, by any other
         party to this Agreement without prior written notice and, except as may
         be legally required, or as may be legally required for a public
         offering of securities, or as may be required for recording purposes,
         without first obtaining the approval of the other party and agreement
         upon the nature and text of such announcement, such agreement and/or
         approval not to be unreasonably withheld. Except as otherwise required
         by law, the party desiring to make any such public announcement or
         public disclosure shall inform the other party of the proposed
         announcement or disclosure at least five (5) business days prior to
         public release, and shall provide the other party with a written copy
         thereof, in order to allow such other party to comment upon such
         announcement or disclosure. This Paragraph shall not apply to any
         information in a public announcement or public disclosure that is
         information essentially identical to that contained in a previous
         public announcement or public disclosure agreed to pursuant to this
         paragraph.

9.4      The confidentiality obligations under Paragraphs 9.1 and 9.2 shall not
         apply to the extent that a party is required to disclose information by
         applicable law, regulation or order of a governmental agency or a court
         of competent jurisdiction; provided, however, that to the extent
         practical such party (a) shall provide written notice thereof to the
         other party and consult with the other party prior to such disclosure
         with respect, thereto, and (b) shall provide the other party sufficient
         opportunity to object to any such disclosure or to request confidential
         treatment thereof, and provide reasonable assistance as requested in
         connection therewith.

9.5      Both parties agree that all RESEARCH PLANS submitted by a party to the
         other party

                                     -24-

<PAGE>

         pursuant to this Agreement shall be strictly confidential and that all
         RESEARCH PLANS will not be utilized by or on behalf of the receiving
         party for any purpose other than as authorized under this Agreement.

9.6      Each party hereto acknowledges that the remedy at law for breach by any
         party of its obligations under this Section 9 is inadequate and that
         each party shall be entitled to equitable remedies, including
         injunctive relief, in the event of a breach by the other party.

9.7      The provisions of this Section 9 are in addition to an do not supercede
         and are not superceded by similar provisions in any other agreements.

10       PATENT PROSECUTION AND LITIGATION

10.1     All right, title and interest to the VICAL TECHNOLOGY and all patent
         rights and other intellectual property rights therein shall belong
         solely to VICAL. VICAL shall have the sole right and responsibility for
         the filing, prosecution and maintenance of patents and patent
         applications directed thereto.

10.2     All right, title and interest to the HGS TECHNOLOGY and all patent
         rights and other intellectual property rights therein shall belong
         solely to HGS. HGS shall have the sole right and responsibility for the
         filing, prosecution and maintenance of patents and patent applications
         directed thereto.

10.3     With respect to any patent covering HGS IMPROVEMENTS or VICAL
         IMPROVEMENTS that is a joint invention of both HGS and VICAL, HGS and
         VICAL shall share equally in the cost and expense thereof. Unless the
         parties otherwise agree, HGS shall be the lead party on HGS
         IMPROVEMENTS and VICAL shall be the lead party on VICAL IMPROVEMENTS.
         The lead party shall consult with the other with respect to strategies
         for filing, prosecution and maintenance of patents and patent
         applications for which it bears responsibility under this paragraph,
         and shall keep the other reasonably informed with regard to filing,
         prosecution and maintenance activity for such patents and patent
         applications. In the event the lead party does not intend to prepare,
         file, prosecute and/or maintain patent protection in any country with
         respect to such joint invention, the lead party shall notify the other
         party and the other party may

                                     -25-

<PAGE>

         assume such responsibility at its own cost and expense. Any patent on
         such joint invention shall be considered both an HGS PATENT and a VICAL
         PATENT.

10.4     Both parties will provide the other reasonable assistance to enable the
         other to prepare, file, prosecute and maintain patents pursuant to this
         Article 10.

10.5     In the event of the institution of any suit by a THIRD PARTY,

         (a)      against VICAL, its AFFILIATES, or its licensees (other than
                  HGS) for patent infringement involving the manufacture, use,
                  import, export, offer for sale, sale, distribution or
                  marketing of EXCLUSIVE VICAL PRODUCT, VICAL shall promptly
                  notify HGS in writing. As between HGS and VICAL, VICAL shall
                  be solely responsible for the cost and expense of such action
                  and any liability, which results therefrom;

         (b)      against HGS, its AFFILIATES, or its licensees (other than
                  VICAL) for patent infringement involving the manufacture, use,
                  import, export, offer for sale, sale, distribution or
                  marketing of EXCLUSIVE HGS PRODUCT, HGS shall promptly notify
                  VICAL in writing. As between HGS and VICAL, HGS shall be
                  solely responsible for the cost and expense of such action and
                  any liability, which results therefrom;

         (c)      The party defending an action under this Paragraph 10.5 shall
                  have full control over its conduct, including settlement
                  thereof provided such settlement shall not be made without the
                  prior written consent of the other party if it would adversely
                  affect the patent rights of such party licensed hereunder.

10.6     In the event that HGS or VICAL becomes aware of actual or threatened
         infringement of a VICAL PATENT or HGS PATENT that claims an EXCLUSIVE
         VICAL PRODUCT or EXCLUSIVE HGS PRODUCT or the use thereof, that party
         shall promptly notify the other party in writing. The owner of the
         VICAL PATENT or HGS PATENT shall have the first right but not the
         obligation to bring, at its own expense, an infringement action against
         any THIRD PARTY and to use the other party's name in connection
         therewith. If the owner of the patent does not commence a particular
         infringement action within ninety (90) days, the other party, after
         notifying the owner in writing, shall be entitled to bring such
         infringement action, in its own name and/or in the name of the patent
         owner, at its own expense to the extent that such party is licensed
         thereunder. The foregoing notwithstanding, in the event that an alleged
         infringer certifies pursuant to 21 U.S.C. Section 355(b)(2)(A)(iv)
         against an issued VICAL PATENT or HGS PATENT that claims EXCLUSIVE
         VICAL PRODUCT or EXCLUSIVE HGS PRODUCT or the use thereof,

                                     -26-

<PAGE>

         as between the patent owner and the owner of the product, the party
         receiving notice of such certification shall immediately notify the
         other party of such certification, and if fourteen (14) days prior
         to expiration of the forty five (45) day period set forth in 21
         U.S.C. Section 355(c)(3)(C), the owner of the patent fails to
         commence an infringement action, the party receiving notice, in its
         sole discretion, at its own expense and to the extent that it is
         licensed under the patent, shall be entitled to bring such
         infringement action in its own name and/or in the name of the patent
         owner. The party conducting an action under this Paragraph 10.6
         shall have full control over its conduct, including settlement
         thereof provided such settlement shall not be made without the prior
         written consent of the other party if it would adversely affect the
         patent rights of such party licensed hereunder. The licensing party
         (i.e., the patent owner) and the licensed party (i.e., the owner of
         the product) shall reasonably assist one another and cooperate in
         any such litigation at the other's request, each such party paying
         its own costs and expenses. The party conducting the litigation
         shall periodically reimburse the other party for its reasonable and
         actual out-of-pocket expenses incurred at the request of the party
         conducting the litigation for assisting in the litigation, which
         reimbursement shall be made within thirty (30) days of receipt by
         the party conducting the litigation of itemized invoices from the
         assisting party documenting such expenses.

10.7     Any recovery made by a party as the result of an action for patent
         infringement it has conducted under Paragraph 10.6 shall be distributed
         as follows:

         (a)      The party conducting the action shall recover its actual out
                  -of-pocket expenses, and then shall reimburse the other party
                  for any unreimbursed actual and out-of-pocket expenses.

         (b)      To the extent that the recovery exceeds the total of item (a),
                  the excess shall be kept by the party conducting the action,
                  provided, however, that to the extent that (i) the recovery is
                  based on an award of lost sales/profits, and (ii) the party
                  conducting the action would have incurred a royalty obligation
                  to the other party based upon such sales, the party to whom
                  such royalties would have been due shall receive a proportion
                  of the excess recovery corresponding to the royalty percentage
                  it would have otherwise been due.

10.8     The parties shall periodically keep one another reasonably informed of
         the status of their respective activities regarding any such litigation
         or settlement thereof.

                                     -27-

<PAGE>

11       STATEMENTS AND REMITTANCES

11.1     VICAL and HGS, as the case may be, shall keep and require its
         AFFILIATES and licensees to keep complete and accurate records of all
         sales and calculations for NET SALES of PRODUCTS. Each party shall have
         the right, at its expense, through an independent certified public
         accounting firm of nationally recognized standing reasonably acceptable
         to the other party, to examine pertinent financial records during
         regular business hours upon proper advance written notice during the
         life of this Agreement and for *** after its termination for the
         purpose of verifying and reporting to HGS or VICAL as to the
         computation of the royalty payments made hereunder during the preceding
         *** prior to the date of such examination; provided, however, that such
         examination shall not take place more often than once a year; provided
         further that such accountant shall report only as to the accuracy of
         the royalty statements and payments, including the magnitude and source
         of any discrepancy. VICAL, HGS, and their respective AFFILIATES and
         licensees shall be required to maintain such sales and royalty
         calculation records for ***. The accountant shall execute customary
         confidentiality agreements prior to any examination, reasonably
         satisfactory in form and substance to both parties, to maintain in
         confidence all information obtained during the course of any such
         examination, except for disclosure to the parties, as necessary for the
         above purpose.

11.2     Within sixty (60) days after the close of each calendar quarter, VICAL
         and HGS, as the case may be, shall deliver to the other party a true
         accounting of all amounts owing hereunder sold by it and its licensees
         and distributors during such calendar quarter and shall at the same
         time pay all amounts due.

11.3     All royalties and other payments due under this Agreement shall be
         payable in U.S. dollars.

11.4     Royalties payable on sales in countries other than the United States
         shall be calculated by

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                  -28-
<PAGE>

         multiplying the appropriate royalty rate times the sales in each
         currency in which they are made and converting the resulting amount
         into United States dollars, at the rates of exchange as reported in The
         Wall Street Journal as published under the caption

          "Currency Trading", on the last business day in New York, New York of
         each royalty period. If the Wall Street Journal ceases to be published,
         then the rate of exchange to be used shall be that reported in such
         other business publication as all parties reasonably agree. Such
         payments shall be without deduction of exchange, collection, or other
         charges. If, due to restrictions or prohibitions imposed by a national
         or international authority, payments cannot be made as aforesaid, the
         parties shall consult with a view to finding a prompt and acceptable
         solution, and the parties will deal with such monies as the other party
         may lawfully direct at no additional out-of-pocket expense to the party
         owed the royalty. Notwithstanding the foregoing, if royalties cannot be
         remitted for any reason within six (6) months after the end of the
         calendar quarter during which they are earned, then the party owing the
         royalty shall be obligated to deposit the royalties in a bank account
         in the country of sale in the name of the other party. Each party shall
         deduct any taxes which the party is obligated to pay and/or withhold in
         a country based on royalties due to the other based on sales in such
         country from royalty payments due for such country under this Agreement
         and pay them to the proper authorities as required by applicable laws.
         Each party shall maintain official receipts of payment of any such
         taxes and forward these receipts to the other within sixty (60) days.

11.5     All payments to be made hereunder shall be by wire transfer of
         immediately available funds to an account designated by HGS or VICAL,
         whoever is to be the recipient of such funds.

12       TERM AND TERMINATION

12.1     This Agreement shall come into effect as of the Effective Date, and
         unless earlier terminated as provided in this Article 12, shall remain
         in full force and effect on a PRODUCT by PRODUCT and country-by-country
         basis, until the last to expire of the applicable party's royalty
         obligations under this Agreement with respect to such PRODUCT in such
         country.

                                       -29-
<PAGE>

12.2     A party shall have the right to terminate this Agreement with respect
         to any PRODUCT upon the material breach by the other party of the other
         party's obligations with respect to such PRODUCT under Article 8 if
         such breach is not cured within sixty (60) days after receipt of
         written notice from such party thereof. Notwithstanding the foregoing,
         a party may not terminate this Agreement during the pendency of an
         arbitration proceeding under this Agreement in which the other party
         reasonably contests whether it has failed to meet its obligations under
         Article 8.

12.3     A party shall have the right to terminate this Agreement in its
         entirety (a) upon the material breach by the other party of the other
         party's obligations to pay any amounts owing hereunder, if such breach
         is not cured within thirty (30) days after receipt of written notice
         from such party thereof, or (b) upon the material breach by the other
         party of the other party's obligations (other than obligations under
         Article 8 or obligations to pay any amounts owing hereunder), if such
         breach is not cured within sixty (60) days after receipt of written
         notice from such party thereof. Notwithstanding the foregoing, a party
         may not terminate this Agreement during the pendency of an arbitration
         proceeding under this Agreement in which the other party reasonably
         contests whether a royalty or other amount is due hereunder, or whether
         it has failed to satisfy its other obligations hereunder.

12.4     Either party, may terminate this Agreement if, at any time, the other
         party shall file in any court or agency pursuant to any statute or
         regulation of any state or country, a petition in bankruptcy or
         insolvency or for reorganization or for an arrangement or for the
         appointment of a receiver or trustee of the party or of its assets, or
         if the other party proposes a written agreement of composition or
         extension of its debts, or if the other party shall be served with an
         involuntary petition against it, filed in any insolvency proceeding,
         and such petition shall not be dismissed within sixty (60) days after
         the filing thereof, or if the other party shall propose or be a party
         to any dissolution or liquidation, or if the other party shall make an
         assignment for the benefit of creditors.

12.5     Neither party shall have the right to terminate this Agreement except
         under Paragraphs 12.2, 12.3 and 12.4, provided however that nothing in
         this Agreement shall limit any remedies for breach which may be
         available pursuant to a judgment of a court, in law or

                                      -30-
<PAGE>

         equity, including termination of this Agreement or of any or all rights
         hereunder, except that any action seeking remedies for breach of this
         Agreement shall be conducted in accordance with Article 16.

12.6     Notwithstanding termination of this Agreement, the rights and
         obligations of the parties under Articles 9, 10, 12, 13, 14 and 16 and
         Paragraphs 3.12, 3.13, 3.14 and 3.15 shall survive such termination, as
         well as any provision not specified in this paragraph which is clearly
         meant to survive termination of this Agreement. Upon expiration of this
         Agreement under Paragraph 12.1 with respect to a particular PRODUCT in
         a particular country, the licenses granted under Paragraphs 3.3 and 3.6
         under VICAL TECHNOLOGY and HGS TECHNOLOGY shall survive on a
         non-exclusive basis.

12.7     Termination of the Agreement in accordance with the provisions hereof
         shall not limit remedies that may be otherwise available in law or
         equity.

13       WARRANTIES AND REPRESENTATIONS

13.1     Each of HGS and VICAL hereby represents, warrants and covenants to the
         other, as of the date of this Agreement, as follows:

         (a)      it is a corporation duly organized and validity existing under
                  the laws of the state of its incorporation;
         (b)      the execution, delivery and performance of this Agreement by
                  such party has been duly authorized by all requisite corporate
                  action;
         (c)      it has the power and authority to execute and deliver this
                  Agreement and to perform its obligations hereunder, including,
                  without limitation, the right, power and authority to grant
                  the licenses under Article 3;
         (d)      the execution, delivery and performance by such party of this
                  Agreement and its compliance with the terms and provisions
                  hereof to such party's best knowledge does not conflict with
                  or result in a breach of any of the terms and provisions of or
                  constitute a default under (i) a loan agreement, guaranty,
                  financing agreement,

                                  -31-
<PAGE>

                  agreement affecting a product or other agreement or instrument
                  binding or affecting it or its property; (ii) the provisions
                  of its charter documents or bylaws; or (iii) any order, writ,
                  injunction or decree of any court or governmental authority
                  entered against it or by which any of its property is bound;
                  and
         (e)      this Agreement constitutes such party's legal, valid and
                  binding obligation enforceable against it in accordance with
                  its terms subject, as to enforcement, to bankruptcy,
                  insolvency, reorganization and other laws of general
                  applicability relating to or affecting creditors' rights and
                  to the availability of particular remedies under general
                  equity principles.

13.2     No party to this Agreement has in effect, and, after the date of this
         Agreement, no party shall enter into any written agreement that would
         be inconsistent with its obligations under this Agreement.

13.3     NOTHING IN THIS AGREEMENT SHALL BE CONSTRUED AS A WARRANTY THAT VICAL
         PATENTS OR HGS PATENTS ARE VALID OR ENFORCEABLE OR THAT THEIR EXERCISE
         OR THE EXERCISE OF HGS TECHNOLOGY OR VICAL TECHNOLOGY DOES NOT INFRINGE
         ANY PATENT RIGHTS OF THIRD PARTIES. A HOLDING OF INVALIDITY OR
         UNENFORCEABILITY OF ANY SUCH PATENT, FROM WHICH NO FURTHER APPEAL IS OR
         CAN BE TAKEN, SHALL NOT AFFECT ANY OBLIGATION HEREUNDER, BUT SHALL ONLY
         ELIMINATE ROYALTIES OTHERWISE DUE UNDER SUCH PATENT FROM THE DATE SUCH
         HOLDING BECOMES FINAL.

13.4     EXCEPT AS OTHERWISE EXPRESSLY SET FORTH HEREIN HGS AND VICAL MAKE NO
         REPRESENTATIONS OR EXTEND ANY WARRANTIES OF ANY KIND, EITHER EXPRESS OR
         IMPLIED, INCLUDING, BUT NOT LIMITED TO, WARRANTIES OF MERCHANTABILITY
         OR FITNESS FOR A PARTICULAR PURPOSE OR NONINFRINGEMENT.

13.5     Each party shall use any materials provided by the other party under
         this Agreement in compliance with all applicable laws and regulations.

                                    -32-
<PAGE>

14       INDEMNIFICATION

14.1     VICAL shall defend, indemnify and hold harmless HGS, its AFFILIATES,
         licensors of HGS and each of their respective directors, officers,
         shareholders, agents and employees, from and against any and all
         liability, loss, damages and expenses (including reasonable attorneys'
         fees) as the result of claims, demands, actions or proceedings by any
         THIRD PARTY which are made or instituted against any of them arising
         out of the development, manufacture, possession, distribution, use,
         testing, sale or other disposition of any EXCLUSIVE VICAL PRODUCT by or
         through VICAL, its AFFILIATES or any THIRD PARTY granted rights by
         VICAL under this Agreement. VICAL's obligation to defend, indemnify and
         hold harmless shall include claims, demands, actions or proceedings,
         whether for money damages or equitable relief by reason of alleged
         personal injury (including death) to any person or alleged property
         damage, provided, however, the indemnity shall not extend to any claims
         against an indemnified party which result from the gross negligence or
         willful misconduct of an indemnified party. VICAL shall have the
         exclusive right to control the defense of any action which is to be
         indemnified in whole by VICAL hereunder, including the right to select
         counsel reasonably acceptable to HGS to defend HGS and the indemnified
         parties hereunder, and to settle any claim, demand, action or
         proceeding, provided that, without the prior written consent of HGS
         (which shall not be unreasonably withheld or delayed), VICAL shall not
         agree to settle any claim, demand, action or proceeding against HGS to
         the extent such claim has a material adverse effect on HGS. The
         provisions of this Paragraph 14.1 shall survive and remain in full
         force and effect after any termination, expiration or cancellation of
         this Agreement and the obligation hereunder shall apply whether or not
         such claims are rightfully brought. VICAL shall require each licensee
         to agree to indemnify HGS in a manner consistent with this Paragraph
         14.1.

14.2     HGS shall defend, indemnify and hold harmless VICAL, its AFFILIATES,
         licensors of VICAL and each of their respective directors, officers,
         shareholders, agents and employees, from and against any and all
         liability, loss, damages and expenses (including reasonable attorneys'
         fees) as the result of claims, demands, actions or proceedings by a
         THIRD PARTY which are made or instituted against any of them arising
         out of the

                                     -33-
<PAGE>

         development, manufacture, possession, distribution, use, testing,
         sale or other disposition of EXCLUSIVE HGS PRODUCT by or through
         HGS, its AFFILIATES or any THIRD PARTY granted rights by HGS
         under this Agreement. HGS' obligation to defend, indemnify and hold
         harmless shall include claims, demands, actions or proceedings, whether
         for money damages or equitable relief by reason of alleged personal
         injury (including death) to any person or alleged property damage,
         provided, however, the indemnity shall not extend to any claims against
         an indemnified party which result from the gross negligence or willful
         misconduct of an indemnified party. HGS shall have the exclusive right
         to control the defense of any action which is to be indemnified in
         whole by HGS hereunder, including the right to select counsel
         reasonably acceptable to VICAL to defend VICAL and the indemnified
         parties hereunder, and to settle any claim, demand, action or
         proceeding, provided that, without the prior written consent of VICAL
         (which shall not be unreasonably withheld or delayed), HGS shall not
         agree to settle any claim, demand, action or proceeding against VICAL
         to the extent such claim has a material adverse effect on VICAL. The
         provisions of this Paragraph 14.2 shall survive and remain in full
         force and effect after any termination, expiration or cancellation of
         this Agreement and the obligation hereunder shall apply whether or not
         such claims are rightfully brought. HGS shall require each licensee to
         agree to indemnify VICAL in a manner consistent with this Paragraph
         14.2.

14.3     A person or entity that intends to claim indemnification under this
         Article 14 (the "Indemnitee") shall promptly notify the other party
         (the "Indemnitor") of any claim, demand, action or proceeding for which
         the Indemnitee intends to claim such indemnification, and the
         Indemnitor, after it determines that indemnification is required of it,
         shall assume the defense thereof with counsel selected by the
         Indemnitor and reasonably acceptable to the other party, provided,
         however, that an Indemnitee shall have the right to retain its own
         counsel, with the fees and expenses to be paid by the Indemnitor if
         Indemnitor does not assume the defense; or, if representation of such
         Indemnitee by the counsel retained by the Indemnitor would be
         inappropriate due to actual or potential conflicts of interest between
         such Indemnitee and any other party represented by such counsel in such
         proceedings. The indemnity agreement in this Article 14 shall not apply
         to amounts paid in settlement of any claim, demand, action or

                                    -34-
<PAGE>

         proceeding if such settlement is effected without the consent of the
         Indemnitor, which consent shall not be unreasonably withheld or
         delayed. The failure to deliver notice to the Indemnitor within a
         reasonable time after the commencement of any such action, if
         prejudicial to its ability to defend such action, shall relieve such
         Indemnitor of any liability to the Indemnitee under this Article 14,
         but failure to deliver notice to the Indemnitor will not relieve it of
         any liability that it may have to any Indemnitee otherwise than under
         this Article 14. The Indemnitee under this Article 14, its employees
         and agents, shall cooperate reasonably with the Indemnitor and its
         legal representatives in the investigations of any claim, demand,
         action or proceeding covered by this indemnification. In the event that
         each party claims indemnity from the other and one party is finally
         held liable to indemnify the other, the Indemnitor shall additionally
         be liable to pay the reasonable legal costs and attorneys' fees
         incurred by the Indemnitee in establishing its claim for indemnity.

15       FORCE MAJEURE

15.1     If the performance by a party of any obligation under this Agreement
         (other than an obligation for a payment of money), is prevented,
         restricted, interfered with or delayed by reason of any reasonable,
         unforeseeable cause beyond the reasonable control of the party liable
         to perform, the party so affected shall, upon giving written notice to
         the other party, be excused from such performance to the extent of such
         prevention, restriction, interference or delay, provided that the
         affected party shall use its commercially reasonable efforts to avoid
         or remove such causes of non-performance and shall continue performance
         with the utmost dispatch whenever such causes are removed. When such
         circumstances arise, the parties shall discuss what, if any,
         modification of the terms of this Agreement may be required in order to
         arrive at an equitable solution.

16       DISPUTE RESOLUTION

16.1     This Agreement shall be construed and enforced in accordance with the
         laws of the State of Delaware (without reference to the conflicts of
         law principles thereof).

16.2     In the event of any controversy, dispute or claim arising out of or
         relating to any provision of this Agreement or the breach thereof, the
         parties shall use good faith efforts

                                  -35-
<PAGE>

         to settle such controversy, dispute, or claim amicably between
         themselves.

16.3     Should the parties fail to reach mutually acceptable settlement of any
         controversy, dispute or claim which may arise out of or in connection
         with this Agreement, or the breach, termination or validity thereof
         (other than with respect to patent validity) shall be settled by final
         and binding arbitration pursuant to the Commercial Arbitration Rules of
         the American Arbitration Association ("AAA") as herein provided.

         (a)      The Arbitration Tribunal shall consist of three arbitrators.
                  Each party shall nominate in the request for arbitration and
                  the answer thereto one arbitrator and the two arbitrators so
                  named will then jointly appoint the third arbitrator as
                  chairman of the Arbitration Tribunal. If one party fails to
                  nominate its arbitrator or, if the parties' arbitrators cannot
                  agree on the person to be named as chairman within sixty (60)
                  days, the necessary appointments shall be made under the rules
                  of the AAA.

         (b)      The place of arbitration shall be in Chicago, Illinois and the
                  arbitration proceedings shall be held in English. The
                  procedural law of the State of Illinois shall apply where the
                  AAA Rules are silent.

The award of the Arbitration Tribunal shall be final and judgment upon such an
award may be entered in any competent court or application may be made to any
competent court for judicial acceptance of such an award and order of
enforcement. Notwithstanding the foregoing, nothing contained herein shall
prevent either party from seeking interim relief from a court of competent
jurisdiction pending the establishment of or a decision by a panel of
arbitrators.

17       SEPARABILITY

17.1     In the event any portion of this Agreement shall be held illegal, void
         or ineffective, the remaining portions hereof shall remain in full
         force and effect.

17.2     If any of the terms or provisions of this Agreement are in conflict
         with any applicable statute or rule of law, then such terms or
         provisions shall be deemed inoperative to the extent that they may
         conflict therewith and shall be deemed to be modified to conform with
         such statute or rule of law.

17.3     In the event that the terms and conditions of this Agreement are
         materially altered as a result of Paragraphs 17.1 or 17.2, the parties
         will, in good faith, renegotiate the terms and conditions of this
         Agreement to resolve any inequities.

                                -36-
<PAGE>

18       ENTIRE AGREEMENT

18.1     This Agreement, together with the Appendices hereto, entered into as of
         the date written above constitutes the entire agreement between the
         parties relating to the subject matter hereof and supersedes all
         previous writings and understandings. No terms or provisions of this
         Agreement shall be varied or modified by any prior or subsequent
         statement, conduct or act of either of the parties, except that the
         parties may amend this Agreement by written instruments specifically
         referring to and executed in the same manner as this Agreement.

19       NOTICES

19.1     Any notice required or permitted under this Agreement shall be
         hand-delivered or sent by express delivery service or certified or
         registered mail, postage prepaid, or by fax with written confirmation
         by mail, to the following addresses of the parties:

                  HUMAN GENOME SCIENCES, INC.
                  9410 Key West Avenue
                  Rockville, MD  20850
                  Attn:  Senior Vice President, Corporate Development
                  Fax:   301-762-5181

                  copy to:
                  HUMAN GENOME SCIENCES, INC.
                  9410 Key West Avenue
                  Rockville, Maryland 20850
                  Attn:  General Counsel
                  Fax:   301-309-8439

                  VICAL INCORPORATED
                  9373 Towne Center Drive
                  San Diego, California  92121
                  Attn:  President
                  Fax:   858-646-1150

                  copy to:
                  PILLSBURY MADISON & SUTRO
                  50 Fremont Street
                  San Francisco, California 94105
                  Attn:  Thomas E. Sparks, Jr.
                  Fax:   415-983-7396

19.2     Any notice required or permitted to be given concerning this Agreement
         shall be

                                     -37-
<PAGE>

         effective upon receipt by the party to whom it is addressed.

20       ASSIGNMENT AND CHANGE OF CONTROL

20.1     This Agreement and the licenses herein granted shall be binding upon
         and inure to the benefit of the parties and their respective permitted
         assignees and successors in interest of the respective parties. Neither
         this Agreement nor any interest hereunder shall be assignable by a
         party without the prior written consent of the other party and any
         attempted assignment contrary to this Paragraph 20.1 shall be void and
         without force and effect. Notwithstanding the foregoing, a party may
         assign this Agreement and all its rights and obligations hereunder to
         any AFFILIATE or to any THIRD PARTY in connection with the transfer or
         sale of all or substantially all of its business, or all or
         substantially all of its assets to which this Agreement relates, or in
         the event of its merger, consolidation, change in control or similar
         transaction, without obtaining the consent of the other party, provided
         that the THIRD PARTY assignee or surviving entity assumes in writing
         all of its obligations under this Agreement.

20.2     ***

21       COUNTERPARTS

21.1     This Agreement may be executed in any number of counterparts, and each
         such counterpart shall be deemed an original instrument, but all such
         counterparts together shall constitute but one agreement.

22       WAIVER

22.1     Any delay or failure in enforcing a party's rights under this Agreement
         or any waiver as to a particular default or other matter shall not
         constitute a waiver of such party's rights to the future enforcement of
         its rights under this Agreement, nor operate to bar the exercise or
         enforcement thereof at any time or times thereafter, excepting only as
         to an express

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                     -38-
<PAGE>

         written and signed waiver as to a particular matter for a particular
         period of time.

22.2     Notwithstanding the foregoing, in the event VICAL or HGS challenges
         whether any payments contemplated hereunder (including, without
         limitation royalties or milestones) are due, it shall have the right,
         but not the obligation, to make such payments under protest (reserving
         all rights hereunder) pending resolution of such dispute.

23       INDEPENDENT RELATIONSHIP

23.1     Nothing herein contained shall be deemed to create an employment,
         agency, joint venture or partnership relationship between the parties
         hereto or any of their agents or employees, or any other legal
         arrangement that would impose liability upon one party for the act or
         failure to act of the other party. No party shall have any power to
         enter into any contracts or commitments or to incur any liabilities in
         the name of, or on behalf of, the other party, or to bind the other
         party in any respect whatsoever.

24       FURTHER ACTIONS

24.1     Each party agrees to execute, acknowledge and deliver such further
         instruments and to do all such other acts, as may be necessary or
         appropriate in order to carry out the purposes and intent of this
         Agreement.

                                     -39-
<PAGE>

IN WITNESS WHEREOF, the parties, through their authorized officers, have
executed this Agreement as of the Effective Date.

VICAL INCORPORATED

BY:      /s/ Alain B. Schreiber
   ------------------------------
         Alain B. Schreiber, M.D.
Title:   President and Chief Executive Officer

HUMAN GENOME SCIENCES, INC.

BY:      /s/ Arthur M. Mandell
   ------------------------------
         Arthur M. Mandell
Title:   Sup. Corporate Development

                                     -40-
<PAGE>

                                   APPENDIX A
     ***

         ____________

*** Confidential material redacted and separately filed with the Commission.

                                     -41-
<PAGE>

                                   APPENDIX B

     ***

         ____________

    *** Confidential material redacted and separately filed with the Commission.

                                     -42-

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