Document:

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                                                                   Exhibit 10.18

                                                                  EXECUTION COPY

                         AGREEMENT OF SALE AND PURCHASE

        THIS AGREEMENT OF SALE AND PURCHASE (this "AGREEMENT") made this 28th
day of December, 1999 by and between MACK-CALI REALTY, L.P., a Delaware limited
partnership having an address at c/o Mack-Cali Realty Corporation, 11 Commerce
Drive, Cranford, New Jersey 07016 ("SELLER") and PARSIPPANY OFFICE ASSOCIATES
L.L.C., a New Jersey limited liability company having an address at c/o
Mack-Cali Realty Corporation, 11 Commerce Drive, Cranford, New Jersey 07016
("PURCHASER").

        In consideration of the mutual promises, covenants, and agreements set
forth herein, and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Seller and Purchaser agree as
follows:

                                    ARTICLE I
                                   DEFINITIONS

               SECTION 1.1 DEFINITIONS. For purposes of this Agreement, the
following capitalized terms have the meanings set forth in this Section 1.1:

        "AFFILIATE" of any Person means any other Person directly or indirectly
controlling, controlled by or under common control with such Person. For
purposes of this definition, the term "control" (including the correlative
meanings of the terms "controlling," "controlled by" and "under common control
with"), as used with respect to any Person, shall mean the possession, directly
or indirectly, of the power to direct or cause the direction of the management
policies of such Person, whether through the ownership of voting securities or
by contract or otherwise; PROVIDED (but without limiting the foregoing) that no
pledge of voting securities of any Person without the current right to exercise
voting rights with respect thereto shall by itself be deemed to constitute
control over such Person; PROVIDED, FURTHER, that Purchaser and the Companies
shall not be deemed to be an Affiliate of Seller or Seller's Affiliates
immediately following the Closing.

        "ASSIGNMENT" has the meaning ascribed to such term in Section 10.3(a),
in the form attached hereto as EXHIBIT A.

        "AUTHORITIES" means the various governmental and quasi-governmental
bodies or agencies having jurisdiction over the Properties, or any applicable
portion thereof.

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        "BUSINESS DAY" means any day other than a Saturday, Sunday or a day on
which national banking associations are authorized or required to close.

        "CERTIFICATE AS TO FOREIGN STATUS" has the meaning ascribed to such term
in Section 10.3(g).

        "CLOSING" means the consummation of the purchase and sale of the
Membership Interests contemplated by this Agreement, as provided for in Article
X.

        "CLOSING DATE" means December 28, 1999.

        "CLOSING STATEMENT" has the meaning ascribed to such term in Section
10.4(a).

        "CLOSING SURVIVING OBLIGATIONS" means the rights, liabilities and
obligations set forth in Article VIII and 10.4, Articles XII and XVI, and
Sections 18.2, 18.5, 18.7, 18.9, 18.11 and 18.12, and any other provisions which
pursuant to their terms survive the Closing hereunder.

        "CODE" means the Internal Revenue Code of 1986, as amended.

        "COMPANIES" means Mack-Cali Campus Realty L.L.C., a New Jersey limited
liability company, and Mack-Cali Morris Realty L.L.C., a New Jersey limited
liability company.

        "DOCUMENTS" has the meaning ascribed to such term in Section 8.1(z).

        "EFFECTIVE DATE" means the date first written above.

        "ENVIRONMENTAL LAWS" means each and every federal, state, county and
municipal statute, ordinance, rule, regulation, code, order, requirement,
directive, binding written interpretation and binding written policy
pertaining to Hazardous Substances issued by any Authorities and in effect as
of the date of this Agreement with respect to or which otherwise pertain to
or affect the Properties, or any portion thereof, the use, ownership,
occupancy or operation of the Properties, or any portion thereof, or the
Companies, and as same have been amended, modified or supplemented from time
to time prior to the Effective Date, including but not limited to the
Comprehensive Environmental Response, Compensation and Liability Act of 1980
(42 U.S.C. SECTIONS 9601 et seq.), the Hazardous Substances Transportation
Act (49 U.S.C. SECTIONS 1802 et seq.), the Resource Conservation and Recovery
Act (42 U.S.C. SECTIONS 6901 et seq.), as amended by the Hazardous and Solid
Wastes Amendments of 1984, the Water Pollution Control Act (33 U.S.C.
SECTIONS 1251 et seq.), the Safe Drinking Water Act (42 U.S.C. SECTIONS 300f
et seq.), the Clean Water Act (33 U.S.C. SECTIONS 1321 et seq.), the Clean
Air Act (42 U.S.C. SECTIONS 7401 et seq.), the Solid Waste Disposal Act (42
U.S.C. SECTIONS 6901 et seq.), the Toxic Substances Control Act (15 U.S.C.
SECTIONS 2601 et seq.), the Emergency Planning and Community Right-to-Know
Act of 1986 (42 U.S.C. SECTIONS 11001 et seq.), the Radon and Indoor Air
Quality Research Act (42 U.S.C. SECTIONS 7401 note, et seq.), the National
Environmental Policy Act (42 U.S.C. SECTIONS 4321 et seq.), the Superfund
Amendment Reauthorization Act of 1986 (42 U.S.C. SECTIONS 9601 et seq.), the
Occupational Safety and Health Act (29 U.S.C. SECTIONS 651 et seq.), the New
Jersey Environmental Rights Act (N.J.S.A. 2A:35A-1 et seq.),

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the New Jersey Spill Compensation and Control Act (N.J.S.A. 58:10-23.11 et
seq.), the New Jersey Air Pollution Control Act (N.J.S.A. 26:2C-1 et seq.), the
Hazardous Substances Discharge: Reports and Notices Act (N.J.S.A. 13:1K-15 et
seq.), the Industrial Site Recovery Act (N.J.S.A. 13:1K-6 et seq.), the New
Jersey Underground Storage of Hazardous Substances Act (N.J.S.A. 58:10A-21 et
seq.) (collectively, the "ENVIRONMENTAL STATUTES"), and any and all rules and
regulations which have become effective prior to the Effective Date under any
and all of the Environmental Statutes.

        "FINANCIAL INFORMATION has the meaning ascribed to such term in Section
8.1(z).

        "GOVERNMENTAL REGULATIONS" means all statutes, ordinances (including
without limitation, zoning ordinances), rules and regulations of the Authorities
applicable to Seller or the Companies or the use or operation of the Properties
or any portion thereof.

        "HAZARDOUS SUBSTANCES" means (a) asbestos, radon gas and urea
formaldehyde foam insulation, (b) any solid, liquid, gaseous or thermal
contaminant, including smoke vapor, soot, fumes, acids, alkalis, chemicals,
petroleum products or byproducts, PCBs, phosphates, lead or other heavy metals
and chlorine, (c) any solid or liquid waste (including, without limitation,
hazardous waste), hazardous air pollutant, hazardous substance, hazardous
chemical substance and mixture, toxic substance, pollutant, pollution, regulated
substance and contaminant, as such terms are defined in any of the Environmental
Statutes as such Environmental Statutes have been amended and/or supplemented
from time to time prior to the date of this Agreement, and any and all rules and
regulations promulgated under any of the above, and (d) any other chemical,
material or substance, the use or presence of which, or exposure to the use or
presence of which, is prohibited, limited or regulated by any Environmental
Statutes.

        "IMPROVEMENTS" means all buildings, structures, fixtures, parking areas
and other improvements located on the Real Properties.

        "KNOWLEDGE," "TO ITS KNOWLEDGE," "TO THE BEST OF ITS KNOWLEDGE," "KNOWN
TO IT" means the current actual knowledge of any employee or officer of the
party hereto to which the term applies or of the Companies who have actively and
directly participated in the negotiation and closing of the matters described
herein or who have actively and directly participated in the management or
operation of the Real Properties and who devoted substantive attention

        "LEASE SCHEDULES" has the meaning ascribed to such term in Section
8.1(z).

        "LEASES" means all of the leases and other agreements with Tenants with
respect to the use and occupancy of the Real Properties, together with all
renewals and modifications thereof, if any, and any new leases entered into
after the Effective Date and prior to the Closing.

        "LICENSES AND PERMITS" means, collectively, all of the Companies' right,
title and interest, to the extent assignable, in and to licenses, permits,
certificates of occupancy, approvals, dedications, subdivision maps and
entitlements now or hereafter issued, approved or granted by the Authorities in
connection with the Properties, together with all renewals and modifications

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thereof.

        "MANAGEMENT AGREEMENT" means, collectively, that certain Leasing and
Management Agreement (in form and substance satisfactory to both Seller and
SLAB) dated as of the date hereof between each of the Companies and an Affiliate
of Seller for the management of the Properties.

        "MEMBERSHIP INTERESTS" means 100% of the membership interests owned by
Seller with respect to the Companies.

        "PERSON" means any individual, corporation, limited liability company,
partnership, association, trust or other entity or organization.

        "PERSONAL PROPERTY" means all of the Companies' right, title and
interest in and to all equipment, appliances, tools, supplies, machinery,
artwork, furnishings and other tangible personal property attached to,
appurtenant to, located in and used exclusively in connection with the ownership
or operation of the Improvements and situated at the Properties at the time of
Closing.

        "PHASE I UPDATE" means an updated Phase I environmental report for the
benefit of the Companies from the environmental consultants who prepared the
existing Phase I environmental report on the Properties.

        "PROPERTIES" means the Real Properties, the Improvements and the
Personal Property.

        "PURCHASE PRICE" has the meaning ascribed to such term in Section 3.1.

        "PURCHASER" means Parsippany Office Associates L.L.C., a New Jersey
limited liability company.

        "REAL PROPERTIES" means those certain real properties located at 2
Hilton Court, 7 Campus Drive, 8 Campus Drive, 5 Sylvan Way, 7 Sylvan Way and 2
Dryden Way, all in Parsippany, New Jersey and certain leasehold interests
related thereto, all as more particularly described on the legal description
attached hereto and made a part hereof as EXHIBIT B, together with all of the
Companies' right, title and interest, if any, in and to the appurtenances
pertaining thereto, including but not limited to the Companies' right, title and
interest in and to the adjacent streets, alleys and right-of-ways, and any
easement rights, air rights, subsurface development rights and water rights.

        "RENTALS" has the meaning ascribed to such term in Section 10.4(b).

        "SERVICE CONTRACTS" means all of the Companies' right, title and
interest, to the extent assignable, in and to all service agreements,
maintenance contracts, equipment leasing agreements, warranties, guarantees,
bonds, open purchase orders and other contracts for the provision of labor,
services, materials or supplies relating solely to the Properties, as listed and

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described on EXHIBIT C attached hereto, together with all renewals, supplements,
amendments and modifications thereof, and any new such agreements entered into
after the Effective Date, all to the extent they survive the Closing.

        "SECURITY DEPOSITS" means all security deposits paid to the Companies,
as landlord (together with any interest which has accrued thereon, but only to
the extent such interest has accrued for the account of the Tenant), and not
previously applied to Rental or other charges.

        "SELLER" means Mack-Cali Realty, L.P., a Delaware limited partnership.

        "SLAB" means SLAB Investments Holding, Inc., a Delaware corporation, a
member of the Purchaser.

        "TENANTS" means the tenants or users who are parties to the Leases.

        "TITLE ENDORSEMENTS" means the endorsements to the Title Policies
described in Section 10.3(d).

        "TITLE POLICIES" means those certain owner's title policies in respect
of the Real Properties listed on EXHIBIT G attached thereto.

               SECTION 1.2 REFERENCES: EXHIBITS AND SCHEDULES. Except as
otherwise specifically indicated, all references in this Agreement to Articles
or Sections refer to Articles or Sections of this Agreement, and all references
to Exhibits or Schedules refer to Exhibits or Schedules attached hereto, all of
which Exhibits and Schedules are incorporated into, and made a part of, this
Agreement by reference. The words "herein," "hereof," "hereinafter" and words
and phrases of similar import refer to this Agreement as a whole and not to any
particular Section or Article.

                                   ARTICLE II
                         AGREEMENT OF PURCHASE AND SALE

               SECTION 2.1 AGREEMENT. Seller hereby agrees to sell, convey,
transfer and assign to Purchaser, and Purchaser hereby agrees to purchase,
acquire, assume and accept from Seller, on the Closing Date and subject to the
terms and conditions of this Agreement, all of the Membership Interests.

               SECTION 2.2 INDIVISIBLE ECONOMIC PACKAGE. Purchaser has no right
to purchase, and Seller has no obligation to sell, less than all of the
Membership Interests, it being the express agreement and understanding of
Purchaser and Seller that, as a material inducement to Seller and Purchaser to
enter into this Agreement, Purchaser has agreed to purchase, and Seller has
agreed to sell, all of the Membership Interests, subject to and in accordance
with the terms and conditions hereof.

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                                   ARTICLE III
                                 PURCHASE PRICE

               SECTION 3.1 PURCHASE PRICE. The purchase price for the Membership
Interests (the "PURCHASE PRICE") shall be One Hundred Fifty Two Million and/100
Dollars ($152,000,000) in lawful currency of the United States of America,
payable as provided in Section 3.2.

               SECTION 3.2 METHOD OF PAYMENT OF PURCHASE PRICE. On or before
11:00 a.m. Eastern time on the Closing Date, Purchaser shall pay to Seller the
Purchase Price, as adjusted pursuant to the terms of this Agreement, by Federal
Reserve wire transfer of immediately available funds to the account of Seller.

                                   ARTICLE IV
                            [INTENTIONALLY OMITTED.]

                                    ARTICLE V
                            [INTENTIONALLY OMITTED.]

                                   ARTICLE VI
                            [INTENTIONALLY OMITTED.]

                                   ARTICLE VII
                            [INTENTIONALLY OMITTED.]

                                  ARTICLE VIII
                         REPRESENTATIONS AND WARRANTIES

               SECTION 8.1 SELLER'S REPRESENTATIONS AND WARRANTIES. The
following constitute the sole representations and warranties of Seller, which
representations and warranties shall be true as of the Effective Date and as of
the Closing Date. Seller represents and warrants to Purchaser the following:

               (a) STATUS. Seller is a limited partnership, duly organized and
validly existing under the laws of the State of Delaware with all requisite
power and authority to carry on the business in which it is engaged and to own
the properties it owns. Mack-Cali Campus Realty L.L.C. is a limited liability
company, duly organized and validly existing under the laws of the State of New
Jersey with all

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requisite power and authority to carry on the business in which it is engaged
and to own the properties it owns. Mack-Cali Morris Realty L.L.C. is a limited
liability company, duly organized and validly existing under the laws of the
State of New Jersey with all requisite power and authority to carry on the
business in which it is engaged and to own the properties it owns. Each of the
Companies and Seller is not in violation or breach of its organizational
documents including, without limitation, its Certificate of Formation or LLC
Agreement. Each of Seller and the Companies is duly qualified and licensed to do
business and is in good standing in all jurisdictions where the nature of their
business makes such qualification necessary and has the requisite power and
authority to conduct its business as now being conducted and to own, lease and
sell all of the Properties. Companies possess all franchises, patents,
copyrights, trademarks, trade names, licenses and permits adequate for the
conduct of their businesses substantially as now conducted. Companies do not
have any direct or indirect subsidiaries or any equity interests in any other
entity. Each of Seller and the Companies are not an "investment company," or a
company "controlled" by an "investment company," within the meaning of the
Investment Company Act of 1940, as amended. No election is in effect whereby the
Seller or the Companies are treated as a corporation for tax purposes. Neither
of the Companies owns, nor have they ever owned, any asset or property other
than the Real Properties (and 1 Sylvan Way, Parsippany, New Jersey, in the case
of Mack-Cali Morris Realty LLC which that Company no longer owns or has any
rights or obligations in respect of) and incidental personal property necessary
for the ownership and operation of the Real Properties. The Companies do not now
engage in, nor have they ever engaged in, any business other than that permitted
by their respective LLC operating agreements. The Companies have no obligations,
liabilities or commitments other than those related to the Real Properties and
disclosed to Purchasers. The Companies have not entered into any contract or
agreement with any member, manager, general partner, principal or affiliate of
Seller or any affiliate thereof, except upon terms and conditions that are
intrinsically fair and substantially similar to those that would be available on
an arm's length basis with third parties other than an affiliate. The Companies
have not incurred any debt, secured or unsecured, direct or contingent
(including guaranteeing any obligation), other than trade payables or accrued
expenses incurred in the ordinary course of business of operating the Real
Properties. The Companies have not made any loans or advances to any third party
(including any member, manager, general partner, principal or affiliate of
Seller, or any guarantor). The Companies have done or caused to be done all
things necessary to preserve their existence and limited liability company
formalities.

               (b) AUTHORITY. This Agreement has been duly executed and
delivered by Seller and the execution and delivery of this Agreement and the
performance of Seller's obligations hereunder have been or will, on or prior to
the Closing, be duly authorized by all necessary action on the part of Seller
and the Companies, and no other procedures on the part of Seller or either of
the Companies are necessary in order to permit them to consummate the
transactions contemplated hereby, and this Agreement constitutes the legal,
valid and binding obligation of Seller. Neither Seller nor the Companies is
required to obtain the consent or any other authorization of a person or entity
in connection with execution and delivery of this Agreement and performance of
its obligations under this Agreement.

               (c) NON-CONTRAVENTION. The execution and delivery of this
Agreement by Seller and the consummation by Seller or either of the Companies of
the transactions contemplated hereby will not (i) violate any judgment, order,
statute, writ, injunction, decree, regulation or ruling of any court or
Authority or arbitrator or conflict with, result in a breach of,

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or constitute a default under the organizational documents of Seller or the
Companies, any note or other evidence of indebtedness, any mortgage, deed of
trust or indenture, or any lease or other agreement or instrument to which
Seller or either of the Companies is a party or by which they are bound; (ii)
result in the creation of any lien, charge, claim or encumbrance upon the
Properties by virtue of any of those items set forth in (i) above; or (iii)
require any order, authorization or consent of any Authority or other person or
entity which has not been obtained.

               (d) OWNERSHIP OF MEMBERSHIP INTERESTS. The Membership Interest in
each of the Companies is duly authorized, validly issued, fully paid and
nonassessable, and has not been issued in violation of any preemptive or similar
rights. Seller is the owner of record and beneficially of the Membership
Interests, free and clear of all mortgages, pledges, encumbrances, security
interests, charges, agreements or claims of any kind (collectively, "Liens").
There are no authorized or outstanding options, warrants, calls, subscriptions
or rights, commitments or other agreements of any kind to purchase any
membership interest or capital stock of the Companies or to cause the Companies
to issue any membership interest or shares of capital stock or securities
convertible into or exchangeable or exercisable for any membership interest or
capital stock of any Company. There are no agreements or understandings to which
either of the Companies is a party or by which it is bound with respect to the
voting, sale or transfer of its Membership Interest, other than the limited
liability company agreements. Upon delivery of the Membership Interests against
payment thereof in accordance with this Agreement, Purchaser will acquire good
and marketable title to the Membership Interests, free and clear of any and all
Liens. No Person, other than Purchaser, has any right to acquire any of the
Membership Interests. The Membership Interests constitute all of the membership
interests in each of the Companies.

               (e) FINANCIAL INFORMATION; LIABILITIES AND OBLIGATIONS. There are
no material inaccuracies or omissions in the Financial Information. Except for
those incurred in the ordinary course of business since the date of the
Financial Information, the Financial Information reflects all liabilities of
each of the Companies, accrued, contingent or otherwise, arising out of
transactions effected or events occurring on or prior to the Effective Date of
this Agreement. As of the Closing, each of the Companies will not be liable upon
or with respect to, or obligated in any other way to provide funds in respect of
or to guarantee or assume in any manner, any debt, obligation, dividend or
distribution of any other Person, and there is no basis for the assertion of any
other claims or liabilities of any nature or in any amount against the
Companies.

               (f) ORGANIZATIONAL DOCUMENTS AND RECORDS OF COMPANIES. The copies
of the operating agreement, other organizational documents and the minute books
of the Companies which have been or are delivered to Purchaser hereunder are
true, correct and complete copies thereof.

               (g) TAXES. Each of the Companies has duly and timely filed all
income, excise, corporate, franchise, property, sales, payroll, withholding and
other tax returns and reports required to be filed by it as of the date hereof
and has paid or established adequate reserves for all taxes (including penalties
and interest) which have or may become due pursuant to such returns and any
assessments which have been received by it or otherwise. Except as disclosed in
the Financial Information, no tax audit of the Companies is pending or
threatened,

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and the results of any completed audits are properly reflected in the Financial
Information. Neither of the Companies has granted any extension to any taxing
authority of the limitation period during which any tax liability may be
asserted. No transfer taxes are or shall be due as a result of transfer of the
Membership Interests or the transactions contemplated hereunder or related
hereto.

               (h) SUITS AND PROCEEDINGS. Except as listed in EXHIBIT D, there
are no:

                       (i) legal actions, claims, charges, complaints,
               petitions, suits or similar proceedings or unsatisfied orders
               pending and served, or threatened against the Companies, the
               Seller or the Properties which if adversely determined, might
               adversely affect the value of the Companies or the Properties,
               the continued ownership, occupancy, or operations thereof, or
               Seller's ability to consummate the transactions contemplated
               hereby;

                       (ii) pending or threatened grievances or arbitration
               proceedings or unsatisfied arbitration awards, or judicial
               proceedings or orders respecting awards, relating to any of the
               Properties or their ownership, operation or occupancy;

                       (iii) pending or threatened unfair labor practice orders
               or judicial proceedings or orders with respect thereto relating
               to any of the Properties or their ownership, operation or
               occupancy; or

                       (iv) any other action, proceeding or investigation
               pending or threatened against or involving Seller or either of
               the Companies or any of the Properties that might adversely
               affect the ownership, operation or occupancy of any of the
               Properties or such person so acquiring ownership, operation or
               occupancy.

To the best knowledge of Seller and the Companies, there are no facts which, if
known by a potential claimant or Authority, would give rise to a claim or
proceeding which, if asserted or conducted with results unfavorable to Seller,
would have a material adverse effect on the ownership or operation of the
Properties, the financial condition or prospects of the Properties or the
consummation of the transactions contemplated by this Agreement. For the purpose
of this Section 8.1(a) any of the terms set forth in subsections (i) through
(iv) above which are adequately insured against shall not be considered subject
to disclosure hereunder.

               (i) NON-FOREIGN ENTITY. Seller is not a "foreign person" or
"foreign corporation" as those terms are defined in the Internal Revenue Code of
1986, as amended, and the regulations promulgated thereunder.

               (j) TENANTS. As of the Closing, the only tenants of the
Properties are the Tenants set forth in the Lease Schedules. The information set
forth on each of the Lease Schedules are accurate and complete as of the date
thereon. The Lease Schedules, attached hereto as EXHIBIT E, accurately and
completely set forth in all material respects for each Lease, the following: the
name of the Tenant, the lease expiration date, extension and renewal provisions,

<PAGE>

the base rent payable and the security deposits held thereunder. Seller and the
Companies are in compliance with all legal requirements relating to such
security deposits. The Documents made available to Purchaser pursuant to Section
8.1(z) hereof include true, correct and complete copies of all of the Leases.
The Leases are in full force and effect. Except as shown on the Lease Schedules,
neither the Companies nor the Tenants are in default of any monetary or, to the
best of Sellers' and the Companies' knowledge, non-monetary obligations under
the Leases. No event or omission has occurred which but for the passing of time
or giving of notice or both would be a monetary or non-monetary default, on the
part of either landlord or tenant under any Lease, and there is no outstanding
defense, counterclaim or offset against the payment of any rent or other amount
payable thereunder or against the performance of any obligation thereunder.
Neither Seller nor the Companies have received notice or has knowledge of any
pending or threatened rent strikes, tenant organizations, tenant unions or
tenant interpleader actions. All work and materials, if any, required to be
performed or furnished, as applicable, prior to the date hereof by landlord
under each of the Leases has been performed and furnished in accordance with the
terms of such Leases and fully paid for. All tenant allowances and concessions
(including all rent-free periods) will be paid for and furnished, as applicable,
by Seller by Closing to the extent required by agreement or otherwise so to be
paid for and furnished, as applicable, by Closing. No commission, compensation
or other amount is now or hereafter shall become payable to any broker or other
agent under any written or oral agreement or understanding with any broker or
other agent in connection with any Leases or renewals thereof, or any other
options thereunder. Each such Lease is a bona fide Lease with a Tenant totally
unrelated to and independent of Seller, the Companies or their Affiliates. To
the best knowledge of Seller and the Companies, there are no circumstances or
events affecting the financial condition of any Tenant or otherwise which might
prevent or seriously hinder such Tenant from fulfilling its obligations under
its Lease. Seller and the Companies have no knowledge of any intention or
indication of intention by any Tenant to terminate its Lease or to limit or
alter its Lease in any material respect. No Tenant under a Lease has paid rent
more than thirty (30) days in advance, and the rents under such Leases have not
been waived, released, or otherwise discharged or compromised. Each Lease
constitutes the legal , valid and binding obligation of the Company constituting
the lessor thereof and is enforceable against the tenant thereof. Each tenant
under the Lease has entered into occupancy of the demised premises. Except as
disclosed to Purchaser in writing, there are no management fees payable by any
Company with respect to the management of the Real Properties. Each Tenant has
accepted and is occupying the entire demised premises. No rent has agreed to be
paid more than one month in advance. Rent has been paid in respect of each Lease
through to the date shown on the Lease Schedules attached. No Tenant has
advanced any funds for or on behalf of Landlord for which it has a right to
deduct or offset from rent. All amendments, supplements and modifications to the
Leases are listed on the Lease Schedule. No Tenant has a purchase option or
right of first refusal on the Real Properties or any part thereof or has any
right to additional space.

               (k) SERVICE CONTRACTS. The Service Contracts are legal, valid and
in full force and effect. None of the parties thereto are in default under any
Service Contract. The Documents made available to Purchaser pursuant to Section
5.2 hereof include true, correct and complete copies of all Service Contracts
under which the Companies are currently paying for services rendered in
connection with the Properties. Other than the Leases, the Service Contracts and
the

<PAGE>

Management Agreement, the Companies, as of the Closing, will not be a party
to any other agreements, contracts or commitments.

               (l) COMPLIANCE WITH LAWS. Neither Seller nor any of the Companies
has received any written notice of any violations of Governmental Regulations
with respect to the Companies or the Properties. Neither the Companies nor the
Properties are in material violation of any Governmental Regulations and, to the
knowledge of Seller and the Companies, neither the Companies nor the Properties
are in any other violation of Governmental Regulations. The Real Properties and
Improvements do not require any rights over, or restrictions against, other
property in order to comply with any Governmental Regulations.

               (m) ZONING. The Improvements and the continuation of the present
location, use, occupancy, operation, maintenance, repair and replacement of the
Real Properties or any part thereof, including the present location, use,
occupancy, operation, maintenance, repair and replacement by the Tenants, comply
in full with all zoning requirements and do not depend on or require to any
extent any further ordinance, variance, special exception or other special
governmental approval for their continuing legality. Without limiting the
foregoing, such Improvements and such location, use, occupancy, operation,
maintenance, repair and replacement are not nonconforming uses in respect of
zoning and other governmental requirements. There is no violation of any
recorded restriction, condition or agreement affecting any of the Real
Properties or, to the best knowledge of Seller and the Companies, of any other
restriction, condition or agreement affecting any of the Real Properties; and
neither Seller nor either Company has received notice of, and to the best
knowledge of Seller and the Companies, there does not exist any violation of,
and continuation of the present locations, uses, occupancies and operations will
not result in a violation of, any building, health, safety, disability,
environmental, pollution control, fire or similar law, ordinance, order,
directive or regulation respecting the Real Properties or any part thereof. To
the best knowledge of Seller and the Companies, all Improvements (including all
roads, parking areas, curbs, curb cuts, sidewalks and sewers and other
utilities) in, on or about the Real Properties have been completed and installed
in accordance with the drawings, plans and specifications approved by the
governmental authorities having jurisdiction or as otherwise required by such
governmental authorities. To the best knowledge of Seller and the Companies, all
impact and other similar fees and charges have been paid and no additional
and/or new impact and other similar fees and charges are pending or
contemplated.

               (n) ENVIRONMENTAL LAWS. To the best knowledge of Seller and the
Companies:

        1. the Real Properties are and at all times have been in compliance with
all Environmental Laws:

        2. no notice, demand, claim or other communication has been given to or
served on Seller or either of the Companies or on previous owners or tenants of
the Real Properties from any entity, governmental body or individual claiming
any violation of any of the Environmental Laws or demanding payment,
contribution, indemnification, remedial action, removal action or

<PAGE>

any other action or inaction with respect to any actual or alleged environmental
damage or injury to persons, property or natural resources, and no basis for any
of the foregoing exists;

        3. no above-ground or underground storage tanks, vessels and related
equipment and containers are or ever were located on the Real Properties;

        4. the soil, surface water and ground water of, under, on or around the
Real Properties are free from any Hazardous Substance;

        5. the Real Properties have never been used for or in connection with
the manufacture, refinement, treatment, storage, generation, transport or
hauling of any Hazardous Substance in excess of levels permitted by applicable
Environmental Laws or the disposal of any such material;

        6. no asbestos, asbestos-containing materials or presumed
asbestos-containing materials have been installed, used, incorporated into or
disposed of on the Real Properties;

        7. no PCBs are or ever have been located on, in, or used in connection
with the Real Properties; and

        8. no investigation, administrative order, administrative order by
consent, consent order, agreement, litigation or settlement is proposed or in
existence or threatened or anticipated, with respect to or arising from the
presence of any Hazardous Substance or the transport of Hazardous Substances
with respect to the Real Properties.

               (o) CC&RS. The current use and occupancy of the Real Property and
the Improvements are not in violation of any recorded or unrecorded covenants,
conditions, restrictions, reservations, easements or agreements affecting the
Real Property and the Improvements.

               (p) LICENSES AND PERMITS. The Companies possess all licenses,
permits, certificates of occupancy, entitlements, approvals and other
governmental authorizations to own, operate, occupy, use and lease the
Properties. All certificates, permits, licenses, franchises, authorizations and
approvals which are necessary to permit the lawful access, use, occupancy and
operation of the Properties for their present and intended accesses, uses,
occupancies and operations have been duly and validly obtained, are in full
force and effect, and Seller and the Companies have no knowledge of any pending
threat or contemplation of modification, cancellation or non-renewal of any such
certificate, permit, license, franchise, authorization or approval.

               (q) TITLE. Each of the Companies is the sole owner of good
insurable and marketable title to such Company's respective Real Properties and
Improvements and Personal Property, free and clear of all liens, mortgages,
deeds of trust and other encumbrances and title defects and claims, charges,
obligations, liabilities or rights in favor of third parties except as otherwise
provided in the Title Policies and the Title Endorsements and Purchaser shall
receive

<PAGE>

such title at Closing. To the best knowledge of Seller and the Companies, all
Personal Property is in good working order and condition. The Real Properties
are free and clear of any mechanics; or materialsmen's liens or liens in the
nature thereof, and no rights are outstanding that under law would give rise to
any such liens, except those which are insured against by the Title Policies and
the Title Endorsements. There are no outstanding options or rights of first
offer or refusal to purchase all or any portion of the Real Properties,
Companies' interests therein or ownership thereof.

               (r) HVAC ETC. All water, sewer, electric, heating, ventilating,
air conditioning, drainage facilities, telephone and other utilities required
for ownership, operation or occupancy of the Real Properties or required by
applicable law or currently on, under or at the Real Property or the
Improvements have been installed in accordance with applicable Governmental
Regulations and are in good working order. To the best knowledge of Seller and
the Companies. Said utilities either enter the Real Properties through adjoining
public streets or if they pass through adjoining private land, do so in
accordance with legal, valid and enforceable permanent public or private
easements which will inure to the benefit of Purchaser, its successors and
assigns.

               (s) BANKRUPTCY. Neither Seller nor any of the Companies has
received any notice of attachments, executions, assignments for the benefit of
creditors, or voluntary or involuntary proceedings in bankruptcy, or under any
other debtor relief laws involving Seller and/or the Companies, or pending
against Seller and/or the Companies, or threatened against Seller, the Companies
or the Properties, or contemplated by Seller or the Companies.

               (t) CONDEMNATION. Neither Seller nor any of the Companies has
received any notice of any pending condemnation action with respect to the
Properties, or any part thereof (including any proceeding for widening, change
of grade or limitation on use of streets abutting the Real Properties) and, to
the best knowledge of Seller and the Companies, no such proceeding has been
threatened or is contemplated by any Authority.

               (u) INSURANCE. Neither Seller nor any of the Companies has
received, and neither Seller nor any of the Companies has any other knowledge or
information of, any notice from any insurance company or board of fire
underwriters requesting the performance of any work or alteration with respect
to the Properties, or requiring an increase in the insurance rates applicable to
the Properties. Every policy of insurance relating to any of the Real Properties
has been disclosed to Purchaser in writing and is in full force and effect at
Closing, indicating name of insurer, premium, and coverage.

               (v) CONDITION OF REAL PROPERTIES. To the best knowledge of Seller
and the Companies, there has been no damage or loss to any of the Real
Properties by any fire or other casualty, any act of God or any hazard prior to
the date hereof; and there has been no material change (adverse or otherwise) in
the physical condition of the Improvements since the date of Purchaser's
inspection. No improvements on adjoining properties encroach on the Real
Properties.

<PAGE>

               (w) LATENT DEFECTS. To the best knowledge of Seller and the
Companies, there are no latent defects in any of the Improvements, and the
structural components, exteriors, electrical, gas, plumbing, water, sewer, air
conditioning, heating, ventilating, exhaust, mechanical, security, disability,
life/safety, communication, telephone, cable and other building systems,
equipment and improvements are in good working order, condition and repair, the
roofs, foundations, structures, doors and windows thereof are free from leaks
and the Improvements are free from termite or other infestation. To the best
knowledge of Seller and the Companies, there are no defects or inadequacies in
the Real Properties or any part thereof which might adversely affect the
insurability of the same or which might cause the imposition of extraordinary
insurance premiums therefor or which might create a hazard or a material
operating deficiency.

               (x) TENANT PROPERTY. To the best knowledge of seller and the
Companies, no equipment, fixture or article of personal property owned by
Tenants and removable by them is material to the ownership, operation or
occupancy of any of the Real Properties.

               (y) REAL ESTATE TAXES. Complete and accurate copies of the most
recent real estate and personal property tax bills covering the Properties have
been provided by Seller to Purchaser. Neither Seller nor either of the Companies
has received any notice, or has any knowledge of any increase in any of the
factors comprising such tax bills or any other matters which might increase such
taxes above such amount for any subsequent year. Neither Seller nor either of
the Companies has received any assessment or other notice with respect to any
governmental improvements prior to the date hereof for which the Real Properties
can be assessed; and no such governmental improvements are threatened,
contemplated, proposed or planned or in progress. To the best knowledge of
Seller and the Companies, neither of the Companies has received any notice of
any pending, threatened or contemplated assessments. The Real Properties and
Improvements constitute separate tax parcels for purposes of ad valorem
taxation.

               (z) DOCUMENT REVIEW. Seller heretofore has provided to Purchaser
for inspection true, accurate and complete copies of all of the following
(collectively, the "DOCUMENTS") with respect to the Properties or the Companies:
all existing environmental, engineering or consulting reports and studies of the
Real Properties (including without limitation, the Phase I Update), real estate
tax bills, together with assessments (special or otherwise), ad valorem and
personal property tax bills, covering the period of the Companies' ownership of
the Properties; the most current lease schedules (the "LEASE SCHEDULES");
current operating statements; the Leases, lease files, Service Contracts, and
Licenses and Permits; the Title Policies and the existing surveys; the
organizational documents, such as the operating agreement and amendments
thereto, the minutes and other similar documents of the Companies; and the most
current financial statements and balance sheets of the Companies (the "FINANCIAL
INFORMATION").

               (aa) COPIES AND SCHEDULES. Copies of all the documents listed on
Schedules and Exhibits attached hereto have been delivered to Purchaser. The
copies of all documents delivered by Seller to Purchaser pursuant to the terms
of this Agreement are complete and accurate. The information contained in
attached Schedules is complete and accurate. The representations and warranties
of Seller contained in this Agreement do not omit to state any

<PAGE>

material fact necessary in order to make such representations and warranties not
misleading.

               (bb) ISRA COMPLIANCE. The transactions contemplated by this
Agreement and the Real Properties are not subject to the requirements of the
Industrial Site Recovery Act of New Jersey.

               (cc) SINGLE-MEMBER LLC. Each of the Companies has been properly
treated as a disregarded entity for income tax purposes.

               (dd) 3 SYLVAN WAY. With respect to 3 Sylvan Way, no tenants has
rights to lease or acquire the Real Property known as 5 Sylvan Way.

               (ee) COOPERS & LYBRAND. With respect to 5 Sylvan Way, the former
tenant, Coopers & Lybrand and its successors in title and assigns have no rights
of lease, renewal, extension or any others rights relating to the Real Property
known as 5 Sylvan Way.

               (ff) ERISA. (i) the Companies are not "employee benefit plans" as
defined in Section 3(3) of ERISA, which is subject to Title I of ERISA, or a
"governmental plan" within the meaning of Secton 3(3) of ERISA; (ii) the
Companies are not subject to state statutes regulating investments and fiduciary
obligations with respect to governmental plans; and (iii) one or more of the
following circumstances is true with respect to each of the Companies:

                       (i) Equity interests in the Company are publicly offered
               securities, within the meaning of 29 C.F.R. SECTIONS
               2510.3-101(b)(2);

                       (ii) Less than twenty-five percent (25%) of each
               outstanding class of equity interests in the Company are held by
               "benefit plan investors" within the meaning of 29 C.F.R. SECTIONS
               2510.3-101(f)(2); or

                       (iii) The Company qualifies as an "operating company" or
               a "real estate operating company" within the meaning of 29
               C.F.R. SECTIONS 2510.3-101(c) or (e) or an investment company
               registered under The Investment Company Act of 1940.

               SECTION 8.2 PURCHASER'S REPRESENTATIONS AND WARRANTIES. Purchaser
represents and warrants to Seller the following as of the Effective Date and as
of the Closing Date:

               (a) STATUS. Purchaser is a limited liability company duly
organized and validly existing under the laws of the State of New Jersey.

               (b) AUTHORITY. The execution and delivery of this Agreement and
the performance of Purchaser's obligations hereunder have been duly authorized
by all necessary action on the part of Purchaser and this Agreement constitutes
the legal, valid and binding obligation of Purchaser.

<PAGE>

               (c) NON-CONTRAVENTION. The execution and delivery of this
Agreement by Purchaser and the consummation by Purchaser of the transactions
contemplated hereby will not violate any judgment, order, injunction, decree,
regulation or ruling of any court or Authority or conflict with, result in a
breach of or constitute a default under the organizational documents of
Purchaser, any note or other evidence of indebtedness, any mortgage, deed of
trust or indenture, or any lease or other material agreement or instrument to
which Purchaser is a party or by which it is bound.

               (d) CONSENTS. No consent, waiver, approval or authorization is
required from any person or entity (that has not already been obtained) in
connection with the execution and delivery of this Agreement by Purchaser or the
performance by Purchaser of the transactions contemplated hereby.

               SECTION 8.3 SURVIVAL OF REPRESENTATIONS, WARRANTIES AND
COVENANTS. The representations and warranties of Seller set forth in Section 8.1
will survive the Closing. The Closing Surviving Obligations will survive Closing
without limitation unless a specified period is otherwise provided in this
Agreement. All other representations, warranties, covenants and agreements made
or undertaken by Seller under this Agreement, unless otherwise specifically
provided herein, will not survive the Closing Date but will be merged into the
Assignment and other Closing documents delivered at the Closing.

               SECTION 8.4 INDEMNITY.

               (a) Seller shall indemnify and hold harmless Purchaser and each
member of Purchaser individually, and its directors, officers, shareholders,
employees, successors, affiliates, trustees, partners, or principals from and
against, any actual damages, loss, cost, liability, damage, expense (including
reasonable attorneys' and other professionals' fees and disbursements), penalty
or fine incurred, but shall exclude any consequential, speculative, punitive or
special damages of Purchaser itself or its affiliates, in connection with or
arising from any breach of representation or warranty made in Section 8.1 above.
For the purposes of determining whether a breach of any representation or
warranty made in Section 8.1 above has occurred and of measuring damages arising
out of breaches of representations and warranties in this Agreement, any
qualifications relating to the 'knowledge' of the Seller and/or the Companies
contained in such representations and warranties shall be ignored.

               (b) Seller shall indemnify and hold harmless Purchaser and each
member of Purchaser individually, and its directors, officers, shareholders,
employees, successors, affiliates, trustees, partners, or principals from and
against, any actual loss, cost, liability, damage, expense (including reasonable
attorneys' and other professionals' fees and disbursements), penalty or fine
incurred, but shall exclude any consequential, speculative, punitive or special
damages of Purchaser itself or its affiliates, in connection with or arising
from any claim relating to the Companies and the Real Properties attributable to
the period prior to the Closing.

               (c) In the event that during the ownership of the Real Properties
by the Companies and of the Membership Interests by Purchaser, neither Standard
& Poor nor Moody's

<PAGE>

is rating Seller as investment grade and the book value, determined in
accordance with Generally Accepted Accounting Principles of Seller (excluding
goodwill and adding back all accumulated depreciation and amortization) falls
below $1,500,000,000, within thirty (30) days thereof, Seller shall, at Seller's
sole expense, provide to Purchaser:

                       (i) updated Phase I environmental reports for all of the
               Real Properties reasonably satisfactory to Purchaser prepared by
               the environmental consultant who prepared the most recent such
               reports submitted by Seller to Purchaser prior to Closing; and

                       (ii) title policies in favor of Purchaser reasonably
               satisfactory to Purchaser in the amount of at least $86,000,000
               (but in no event less than an amount which would prevent
               Purchaser from being a co-insurer) in the aggregate for all of
               the Real Properties issued by the title company which issued the
               most recent title policies in favor of Seller or other title
               companies reasonably acceptable to Purchaser.

               (d) If the Seller for any reason fails to comply with
subparagraphs (c)(i) and (ii) above within the above-mentioned thirty (30) day
period, within ten (10) business days from the date of expiration of such
period, Seller shall at the cost of Seller deliver at Seller's sole expense to
Purchaser an irrevocable standby letter of credit in the amount of $86,000,000
to secure Seller's obligations under this Section 8.4. in a form reasonably
acceptable to Purchaser, renewable annually for a period of no less than three
(3) years, and issued by a bank selected by Seller which is rated AA by all
agencies which have jurisdiction to rate the bank, or otherwise reasonably
acceptable to Purchaser. If the selected bank is downgraded below AA after
issuance of the letter of credit, a replacement letter of credit on all of the
same terms set forth herein must be obtained from a AA rated bank as soon as
reasonably possible. If the above-mentioned letter of credit is for any reason
not renewed during the term thereof within 30 days prior to any annual
expiration, the Purchaser shall be able to draw against the letter of credit
prior to its expiration in accordance with its terms.

               (e) In the event that all of the Real Properties are sold by the
Companies or that all of the Membership Interests are sold by Purchaser, on or
prior to the closing of the sale of the Real Properties or the Membership
Interests, Seller shall deliver to Purchaser at Seller's sole expense an updated
Phase I environmental report for all of the Real Properties prepared by the
environmental consultant who prepared the most recent such report submitted by
Seller to Purchaser or such other environmental consultants reasonably
acceptable to Purchaser which are dated on or about the time Seller purchased
such Real Properties.

                       (i) If the above-mentioned updated Phase I environmental
               reports for all of the Real Properties show no adverse change
               from the most recent such reports submitted to and approved by
               Seller prior to Closing, Seller shall have no further obligations
               under this Section 8.4(c).

                       (ii) If the above-mentioned updated Phase I environmental
               reports for

<PAGE>

               any of the Real Properties show any adverse change from the most
               recent such reports submitted to and approved by Seller prior to
               Closing and Seller's investment rating falls or Seller is not
               rated as set forth in subsection (c) above, within ten (10)
               business days from the date of delivery of such reports by
               Seller to Purchaser, Seller shall arrange at Seller's sole
               expense an indemnity, in form and substance reasonably approved
               by Purchaser by a person or entity with a book value determined
               in accordance with GAAP (excluding goodwill and adding back
               accumulated depreciation and amortization) of $100,000,000, as
               verified by Purchaser to its reasonable satisfaction.

               This Section 8.4 shall survive the Closing.

                                   ARTICLE IX
                         CONDITIONS PRECEDENT TO CLOSING

               SECTION 9.1 CONDITIONS PRECEDENT TO OBLIGATION OF PURCHASER. The
obligation of Purchaser to consummate the transaction hereunder shall be subject
to the fulfillment at or prior to the Closing of all of the following
conditions, any or all of which may be waived by Purchaser in its sole
discretion:

               (a) Seller shall have delivered to Purchaser all of the items
required to be delivered to Purchaser pursuant to the terms of this Agreement,
including but not limited to, those provided for in Section 10.3.

               (b) All of the representations and warranties of Seller contained
in this Agreement shall be true and correct in all material respects as of the
date of Closing.

               (c) Seller shall have performed and observed, in all material
respects, all covenants and agreements of this Agreement to be performed and
observed by Seller as of the Closing Date.

               SECTION 9.2 CONDITIONS PRECEDENT TO OBLIGATION TO SELLER. The
obligation of Seller to consummate the transaction hereunder shall be subject to
the fulfillment on or before the date of Closing of all of the following
conditions, any or all of which may be waived by Seller in it sole discretion:

               (a) Seller shall have received the Purchase Price as adjusted
pursuant to, and payable in the manner provided for, in this Agreement.

               (b) Purchaser shall have delivered to Seller all of the items
required to be delivered to Seller pursuant to the terms of this Agreement,
including but not limited to, those provided for in Section 10.2.

               (c) All of the representations and warranties of Purchaser
contained in this Agreement shall be true and correct in all material respects
as of the date of Closing (with

<PAGE>

appropriate modifications permitted under this Agreement or not materially
adverse to Seller).

               (d) Purchaser shall have performed and observed, in all material
respects, all covenants and agreements of this Agreement to be performed and
observed by Purchaser as of the Closing Date.

               (e) The Companies and an Affiliate of Seller shall have entered
into the Management Agreement to become effective as of the Closing.

                                    ARTICLE X
                                     CLOSING

               SECTION 10.1 CLOSING. The consummation of the transaction
contemplated by this Agreement by delivery of documents and payments of money
shall take place on the Closing Date at the office of Weil, Gotshal & Manges,
767 Fifth Avenue (GM Building), New York, New York, or such other place as the
parties agree. At Closing, the events set forth in this Article X will occur, it
being understood that the performance or tender of performance of all matters
set forth in this Article X are mutually concurrent conditions which may be
waived by the party for whose benefit they are intended. The acceptance of the
Assignment by Purchaser shall be deemed to be full performance and discharge of
each and every agreement and obligation on the part of the Seller to be
performed hereunder unless otherwise specifically provided herein.

               SECTION 10.2 PURCHASER'S CLOSING OBLIGATIONS. At the Closing,
Purchaser will deliver the following items to Seller as provided herein:

               (a) The Purchase Price, after all adjustments are made as herein
provided, by Federal Reserve wire transfer of immediately available funds, in
accordance with the timing and other requirements of Section 3.2;

               (b) A counterpart original of the Assignment, duly executed by
Purchaser;

               (c) An original ratification of the Companies' execution and
delivery of the Management Agreement, duly executed by the Purchaser as the new
sole member of the Companies; and

               (d) Evidence reasonably satisfactory to Seller that the person
executing the Assignment and the other Closing documents on behalf of Purchaser
has full right, power and authority to do so.

               SECTION 10.3 SELLER'S CLOSING OBLIGATIONS. At the Closing, Seller
will deliver to Purchaser the following documents:

               (a) A counterpart original of the Assignment, duly executed by
Seller, assigning and transferring to the Purchaser the Membership Interests;

<PAGE>

               (b) The original Management Agreements, duly executed by the
Companies and an Affiliate of Seller which will be the manager thereunder;

               (c)     The Phase I Update;

               (d) Title endorsements commonly referred to as the Fairway
Endorsement and the Non-imputation Endorsement (the "TITLE ENDORSEMENTS") to the
Title Policy in a form satisfactory to Purchaser;

               (e) Evidence reasonably satisfactory to Purchaser that the person
executing the documents delivered by Seller or its Affiliates pursuant to this
Section 10.3 has full right, power, and authority to do so;

               (f) A certificate in the form attached hereto as EXHIBIT F
("CERTIFICATE AS TO FOREIGN STATUS") certifying that Seller is not a "foreign
person" as defined in Section 1445 of the Internal Revenue Code of 1986, as
amended, as well as any form or other document required under applicable laws to
be executed by Seller in connection with any transfer tax applicable to the
transaction contemplated by this Agreement;

               (g) All original Leases, to the extent in Seller's or the
Companies' possession, and all original Licenses and Permits and Service
Contracts in Seller's or the Companies' control bearing on the Properties (to be
delivered to the property manager under the Management Agreement);

               (h) A certificate, dated as of the date of Closing, stating that
the representations and warranties of Seller contained in Section 8.1 are true
and correct in all material respects as of the Closing Date or identifying any
representation or warranty which is not, or no longer is, true and correct and
explaining the state of facts giving rise to the change. If, despite changes or
other matters described in such certificate, the Closing occurs, Seller's
representations and warranties set forth in this Agreement shall be deemed to
have been modified by all statements made in such certificate;

               (i) The Lease Schedules, updated to show any changes and dated as
of no more than five (5) Business Days prior to the Closing Date; and

               (j) UCC Search in respect of Seller regarding assignment of
membership interests at Secretary of State's office

               (k) UCC Searches for fixtures and Personal Property in respect of
the Companies at state, in county of property location and executive office, if
different, or county of residence if applicable

               (l)     Litigation searches for the Companies

<PAGE>

               (m) Tax Lien searches for the Companies

               (n) Amendments of the operating agreements for the Companies to
reflect changes in membership and, in the case of Mack-Cali Morris Realty
L.L.C., removal of reference to 1 Sylvan Way, Parsippany, New Jersey.

               (o) FIRPTA requirements (Federal)

               (p) Original executed Asset Management Agreement

               (q) Approved Budgets for the Companies in form satisfactory to
Purchaser

               (r) Certified Service Contracts List in form satisfactory to
Purchaser

               (s) Certified Rent Roll in respect of the Real Properties in form
satisfactory to Purchaser

               (t) Environmental reliance letter enabling Purchaser to rely on
the Phase I Update in form satisfactory to Purchaser

               (u) Real estate tax bills and assessments and evidence of payment
for last three years in form satisfactory to Purchaser

               (v) Legal opinion of Seller's counsel in form satisfactory to
Purchaser relating to (i) due authority of the Seller; and enforceability of
this Agreement and the Assignments for transfer of the Membership Interests
contemplated hereby and related hereto;

               (w) Tax opinion in form satisfactory to Purchaser

               (x) Surveys of the Real Properties

               (y) The organizational documents in respect of Seller and the
Companies listed on EXHIBIT H annexed hereto

               (z) Documents evidencing transfer of 1 Sylvan way, to a party
other than Purchaser.

               (aa) Such other documents as may be reasonably necessary or
appropriate to effect the consummation of the transaction which is the subject
of this Agreement.

               (bb) All certificates of occupancy in the possession of the
Companies with respect to the Real Properties.

               SECTION 10.4   CLOSING STATEMENT; POST-CLOSING OBLIGATIONS.

<PAGE>

               (a) CLOSING STATEMENT. Seller agrees that the Closing Statement
will reflect the following fair and accurate adjustments (as of 11:59 p.m. on
the day preceding the Closing Date):

                       (i) Seller will receive a credit in the amount of any
               cash on hand or in any bank, savings or other deposit accounts
               held in the name of or for the benefit of the Companies.

                       (ii) Seller will receive a credit for any prepaid amounts
               for periods after the Closing Date under any agreement or
               contracts (including insurance policies) to which the Companies
               are a party and which will survive the Closing.

                       (iii) Seller will receive a credit equal to the value of
               fuel stored at the Real Properties, at the Companies' most recent
               cost, including taxes, on the basis of a reading made within ten
               (10) days prior to the Closing by the Companies' supplier.

                       (iv) Purchaser will receive a credit in the amount of the
               Security Deposits and any prepaid Rents, together with interest
               required to be paid thereon.

                       (v) Purchaser will receive a credit in the amount of the
               utility charges payable by the Companies for periods prior to the
               Closing Date, including, without limitation, electricity, water
               charges and sewer charges, based on the most current information.

                       (vi) Purchaser will receive a credit equal to the amounts
               payable under the Service Contracts for services rendered prior
               to the Closing Date.

                       (vii) Purchaser will receive a credit for any other
               amounts payable under any other agreement or contracts (including
               insurance policies) relating to the Companies or the Property for
               periods prior to the Closing Date and for any other liability
               whatsoever of the Companies incurred or arising prior to the
               Closing Date.

                       (viii) Purchaser will receive a credit in the amount of
               the real estate taxes due and payable for periods prior to the
               Closing Date, based on the most current information.

Within fifteen (15) days following the Closing, Seller will deliver to Purchaser
the Closing Statement. Any amounts shown by the Closing Statement to be due by
any party to the other pursuant to this Section 10.4(a) will be paid within
fifteen (15) days following execution of the Closing Statement by Purchaser and
Seller. Section 10.4 (a) shall survive the Closing.

               (b) POST-CLOSING RECEIPT OF RENTAL. All Rentals received by the
Companies

<PAGE>

or the Purchaser on or after the Closing Date shall first be applied by
Purchaser for payment of Rentals owing in respect of periods commencing on or
after the Closing Date then, to the extent any Rentals so received are
remaining, the remainder shall be paid or turned over to Seller to the extent
attributable to any period prior to the Closing Date. "RENTALS" as used herein
includes fixed monthly rentals, additional rentals, percentage rentals,
escalation rentals (which include each Tenant's proportionate share of building
operation and maintenance costs and expenses as provided for under the Lease, to
the extent the same exceeds any expense specified in such Lease), retroactive
rentals, all administrative charges, utility charges, other common area
maintenance charges, real and personal property taxes and assessments, tenant or
real property association dues, storage rentals, special event proceeds,
temporary rents, telephone receipts, locker rentals, vending machine receipts
and other sums, charges, fees or pass-through items payable by Tenants under the
Leases or from other occupants or users of the Properties. The provisions of
this Section 10.4(b) shall survive the Closing indefinitely.

               (c) COST OF DUE DILIGENCE ITEMS IN EVENT OF SALE. In the event
that Purchaser sells or refinances the Membership Interests or the Companies
sell or refinance any of the Real Properties to or with any party other than an
affiliate of Seller, Seller shall bear at its sole expense, the cost of the
following due diligence items if required to be provided by Purchaser or any of
the Companies in connection with any such transaction: (i) engineering reports;
(ii) Phase I environmental reports; (iii) appraisal; (iv) title reports,
searches and endorsements; (v) surveys; (vi) certificates of occupancy.

                                   ARTICLE XI
                            TERMINATION AND REMEDIES

               (a) PURCHASER'S TERMINATION. Provided that Purchaser is not then
in material breach of this Agreement, this Agreement shall terminate, upon
receipt by Seller of Purchaser's written notice of termination without further
notice or action by Purchaser, if any condition to Closing contained in Section
10.2 has not been satisfied or waived by Seller in writing by the Closing Date;

               (b) SELLER'S TERMINATION. Provided that Seller is not then in
material breach of this Agreement, this Agreement shall terminate, upon receipt
by Purchaser of Seller's written notice of termination without further notice or
action by Seller, if any condition to Closing contained in Section 10.3 has not
been satisfied or waived by Purchaser in writing by the Closing Date;

               (c) PURCHASER'S REMEDIES. If Seller materially breaches this
Agreement, Purchaser shall be entitled to pursue the remedy of specific
performance and the return of any deposit (and any interest accrued thereon)
from Seller and Seller shall be liable to Purchaser for such actual costs and
expenses (which shall include, without limitation, reasonable attorneys' fees
and costs) of enforcing the rights of Purchaser under this Agreement. This
Article XI(c) shall survive the Closing.

<PAGE>

               (d) SELLER'S REMEDIES. If Purchaser breaches this Agreement,
Seller shall be entitled to pursue all remedies permitted herein and by law,
including, without any limitation, the remedy of specific performance and the
retention of any deposit (and any interest accrued thereon) from Purchaser.

               (e) INDEMNIFICATION PROCEDURES.

                       (i) If Purchaser (the"Indemnitee") becomes aware of any
               matter for which it believes it is entitled to indemnification
               under Section 8.4, hereof that involves (i) any claim made
               against the Indemnitee or (ii) the commencement of any action,
               suit, investigation, arbitration, or similar proceeding against
               the Indemnitee, the Indemnitee will give Seller (the
               "Indemnifying Party") prompt written notice of such claim or
               commencement of such action, suit, investigation, arbitration, or
               similar proceeding. Such notice will (A) provide (with reasonable
               specificity) the basis on which indemnification is being
               asserted, (B) set forth the actual or estimated amount of damages
               for which indemnification is being asserted, if known, and (C) be
               accompanied by copies of all relevant pleadings, demands and
               other papers served on the Indemnitee.

                       (ii) The Indemnifying Party will have a period of 30-days
               after the delivery of each notice required by Section 11.2(a)
               hereof during which to respond to such notice. If the
               Indemnifying Party elects to defend the claim described in such
               notice or does not respond within such 30-day period, the
               Indemnifying Party will be obligated to compromise or defend (and
               will control the defense of) such claim, at is own expense and by
               counsel chosen by the Indemnifying Party and reasonably
               satisfactory to the Indemnitee. The Indemnitee will cooperate
               fully with the Indemnifying Party and counsel for the
               Indemnifying Party in the defense against any such claim and the
               Indemnitee will have the right to participate at its own expense
               in the defense of any such claim. If the Indemnifying party
               responds within such 30-day period and elects not to defend such
               claim, the Indemnitee will be free to compromise or defend (and
               control the defense of) such claim and to pursue such remedies as
               may be available to the Indemnitee under applicable law.

                       (iii) Any compromise or settlement of any claim (whether
               defended by the Indemnitee or by Indemnifying Party) will require
               the prior written consent of the Indemnitee and the Indemnifying
               Party.

                       (iv) Any reasonable costs or expenses incurred and paid
               by the Indemnitee in connection with the exercise of any of its
               rights under this Section 10.4 or with respect to a matter for
               which it is indemnified under Section 8.4 of this Agreement shall
               be paid by the Indemnifying Party on demand and if the
               Indemnifying Party fails to pay such amounts demanded within five
               (5) days of demand, the amounts demanded will bear interest at
               the lower fifteen (15%) per annum or the maximum applicable
               lawful rate; PROVIDED, HOWEVER, that the Indemnifying Party's
               obligation to pay such costs, expenses and interest shall not

<PAGE>

               apply for any period claimed in the event that Indemnifying Party
               obtains a final judgement or order that the Indemnitee is not
               entitled to indemnification or to payment of costs or expenses
               under the provisions of Section 8.4 or 10.4 of this Agreement.

                                   ARTICLE XII
                                 CONFIDENTIALITY

               SECTION 12.1 PRESS RELEASES. Before either of Seller or Purchaser
discloses in writing to any third party any of the terms and conditions of this
Agreement (or the transaction contemplated hereby), such party shall provide a
copy of such writing to the other party for its review and comment (but not its
approval). Either Seller or Purchaser may request a meeting to discuss any such
writing. The provisions of this Section 12.1 will survive the Closing.

                                  ARTICLE XIII
                            [INTENTIONALLY OMITTED.]

                                   ARTICLE XIV
                            [INTENTIONALLY OMITTED.]

                                   ARTICLE XV
                                   ASSIGNMENT

               SECTION 15.1 ASSIGNMENT. No party shall have any right to assign
this Agreement or any portion thereof.

                                   ARTICLE XVI
                                    BROKERAGE

               SECTION 16.1 BROKERS. Purchaser and Seller represent that they
have not dealt with any brokers, finders or salesmen, in connection with this
transaction, and agree to indemnify, defend and hold each other harmless from
and against any and all loss, cost, damage, liability or expense, including
reasonable attorneys' fees, which either party may sustain, incur or be exposed
to by reason of any claim for fees or commissions made through the other party.
The provisions of this Article XVI will survive any Closing.

                                  ARTICLE XVII
                            [INTENTIONALLY OMITTED.]

<PAGE>

                                  ARTICLE XVIII
                                  MISCELLANEOUS

               SECTION 18.1 WAIVERS. No waiver of any breach of any covenant or
provisions contained herein will be deemed a waiver of any preceding or
succeeding breach thereof, or of any other covenant or provision contained
herein. No extension of time for performance of any obligation or act will be
deemed an extension of the time for performance of any other obligation or act.

               SECTION 18.2 RECOVERY OF CERTAIN FEES. In the event a party
hereto files any action or suit against another party hereto by reason of any
breach of any of the covenants, agreements or provisions contained in this
Agreement, then in that event the prevailing party will be entitled to have and
recover certain fees from the other party including all reasonable attorneys'
fees and costs resulting therefrom. For purposes of this Agreement, the term
"attorneys' fees" or "attorneys' fees and costs" shall mean the fees and
expenses of counsel to the parties hereto, which may include printing,
photostatting, duplicating and other expenses, air freight charges, and fees
billed for law clerks, paralegals and other persons not admitted to the bar but
performing services under the supervision of an attorney, and the costs and fees
incurred in connection with the enforcement or collection of any judgment
obtained in any such proceeding. The provisions of this Section 18.2 shall
survive the entry of any judgment, and shall not merge, or be deemed to have
merged, into any judgment.

               SECTION 18.3 CONSTRUCTION. Headings at the beginning of each
article and section are solely for the convenience of the parties and are not a
part of this Agreement. Whenever required by the context of this Agreement, the
singular will include the plural and the masculine will include the feminine and
vice versa. This Agreement will not be construed as if it had been prepared by
one of the parties, but rather as if both parties had prepared the same. All
exhibits and schedules referred to in this Agreement are attached and
incorporated by this reference, and any capitalized term used in any exhibit or
schedule which is not defined in such exhibit or schedule will have the meaning
attributable to such term in the body of this Agreement. In the event the date
on which Purchaser or Seller is required to take any action under the terms of
this Agreement is not a Business Day, the action will be taken on the next
succeeding Business Day.

               SECTION 18.4 COUNTERPARTS. This Agreement may be executed in
multiple counterparts, each of which, when assembled to include an original
signature for each party contemplated to sign this Agreement, will constitute a
complete and fully executed original. All such fully executed original
counterparts will collectively constitute a single agreement.

               SECTION 18.5 SEVERABILITY. If any term or other provision of this
Agreement is invalid, illegal, or incapable of being enforced by any rule of law
or public policy, all of the other conditions and provisions of this Agreement
will nevertheless remain in full force and effect, so long as the economic or
legal substance of the transactions contemplated hereby is not affected in any
adverse manner to either party. Upon such determination that any term or other
provision is

<PAGE>

invalid, illegal, or incapable of being enforced, the parties hereto will
negotiate in good faith to modify this Agreement so as to reflect the original
intent of the parties as closely as possible in an acceptable manner to the end
that the transactions contemplated hereby are fulfilled to the extent possible.

               SECTION 18.6 ENTIRE AGREEMENT. This Agreement is the final
expression of, and contains the entire agreement between, the parties with
respect to the subject matter hereof, and supersedes all prior understandings
with respect thereto. This Agreement may not be modified, changed, supplemented
or terminated, nor may any obligations hereunder be waived, except by written
instrument, signed by the party to be charged or by its agent duly authorized in
writing, or as otherwise expressly permitted herein.

               SECTION 18.7 GOVERNING LAW. THIS AGREEMENT WILL BE CONSTRUED,
PERFORMED AND ENFORCED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK
EXCEPT TO THE EXTENT THAT THE APPLICATION OF THE LAWS OF THE STATE OF NEW JERSEY
IS MANDATORY. SELLER AND PURCHASER HEREBY IRREVOCABLY SUBMIT TO THE JURISDICTION
OF ANY STATE OR FEDERAL COURT SITTING IN THE CITY OF NEW YORK IN ANY ACTION OR
PROCEEDING ARISING OUT OF OR RELATING TO THIS AGREEMENT AND HEREBY IRREVOCABLY
AGREE THAT ALL CLAIMS IN RESPECT OF SUCH ACTION OR PROCEEDING SHALL BE HEARD AND
DETERMINED IN A STATE OR FEDERAL COURT SITTING IN THE CITY OF NEW YORK.

               SECTION 18.8 NO RECORDING. The parties hereto agree that neither
this Agreement nor any affidavit or memorandum concerning it will be recorded
and any recording of this Agreement or any such affidavit or memorandum by
Purchaser will be deemed a default by Purchaser hereunder.

               SECTION 18.9 FURTHER ACTIONS. The parties agree to execute such
documents and instruments and to do such further acts as may be reasonably
necessary to carry out the provisions of this Agreement.

               SECTION 18.10 EXHIBITS. The following sets forth a list of
Exhibits to the Agreement:

               Exhibit A -    Assignment
               Exhibit B -    Legal Description of Real Properties
               Exhibit C -    List of Service Contracts
               Exhibit D -    Suits and Proceedings
               Exhibit E -    Lease Schedules
               Exhibit F -    Certificate of Foreign Status
               Exhibit G -    List of Title Policies
               Exhibit H -    List of Organizational Documents

               SECTION 18.11 NO PARTNERSHIP. Notwithstanding anything to the
contrary

<PAGE>

contained herein, this Agreement shall not be deemed or construed to make the
parties hereto partners or joint venturers, it being the intention of the
parties to merely create the relationship of Seller and Purchaser with respect
to the Membership Interests to be conveyed as contemplated hereby.

               SECTION 18.12 LIMITATIONS ON BENEFITS, ETC. It is the explicit
intention of Purchaser and Seller that no person or entity other than Purchaser,
the members of Purchaser individually, Seller and, to the extent applicable, the
Companies and the manager under the Management Agreement, and their respective
permitted successors and assigns is or shall be entitled to bring any action to
enforce any provision of this Agreement against any of the parties hereto, and
the covenants, undertakings and agreements set forth in this Agreement shall be
solely for the benefit of, and shall be enforceable only by, Purchaser, the
members of Purchaser individually, Seller and, to the extent applicable, the
Companies and said manager, or their respective successors and assigns as
permitted hereunder. Nothing contained in this Agreement shall under any
circumstances whatsoever be deemed or construed, or be interpreted, as making
any third party (other than the members of Purchaser individually) a beneficiary
of any term or provision of this Agreement or any instrument or document
delivered pursuant hereto, and Purchaser and Seller expressly reject any such
intent, construction or interpretation of this Agreement.

                   [BALANCE OF PAGE INTENTIONALLY LEFT BLANK]

<PAGE>

               IN WITNESS WHEREOF, Seller and Purchaser have respectively
executed this Agreement as of the Effective Date.

SELLER:                      MACK-CALI REALTY, L.P.,
                             a Delaware limited partnership

                             By:    Mack-Cali Realty Corporation,
                                    a Delaware corporation,
                                    its general partner

                                    By:
                                        -----------------------------------
                                        Roger W. Thomas,
                                        Executive Vice President

PURCHASER:                   PARSIPPANY OFFICE ASSOCIATES L.L.C.
                             a New Jersey limited liability company

                             By:    Mack-Cali Realty, L.P.,
                                    a Delaware limited partnership,
                                    its member

                                    By:     Mack-Cali Realty Corporation,
                                            a Delaware corporation,
                                            its general partner

                                            By:
                                               ----------------------------
                                               Roger W. Thomas,
                                               Executive Vice President

                             By:    Slab Investments Holding, Inc.,
                                    a Delaware corporation
                                    its member

                                    By:
                                        -----------------------------------
                                        John Bricker
                                        Assistant Secretary

                               [END OF SIGNATURES]

<PAGE>

00

                                    EXHIBIT H

                 ORGANIZATIONAL DOCUMENTS FOR DELIVERY BY SELLER
KEY

MC                     Mack-Cali Realty L.P.
LLC1                   Mack-Cali Campus Realty LLC
LLC2                   Mack-Cali Morris Realty LLC

<TABLE>
<S>    <C>     <C>
1      For MC:
       a.      Partnership Agreement
       b.      Partnership Certificate
       c.      Certificate of Good Standing
       d.      Certificates of Good Standing for General Partner
       e.      Articles of Incorporation of General Partner (or other organizational documents, as applicable)
       f.      By-Laws of General Partner (or other organizational documents, as applicable)
       g.      Corporate Resolution and Incumbency Certificate of General Partner
       h.      Termination of Agreements

2      For LLC 1:
       a.      Articles of Organization
       b.      LLC Agreement
       c.      Certificates of Good Standing
       d.      Resignation from all offices of Company, including the board of managers, of MC dated the Closing Date

3      For LLC 2:
       a.      Articles of Organization
       b.      LLC Agreement
       c.      Certificates of Good Standing
       d.      Resignation from all offices of Company, including the board of managers, of MC dated the Closing Date
</TABLE><PAGE>

                                                                   Exhibit 10.19

                             OPERATING AGREEMENT OF
                       PARSIPPANY OFFICE ASSOCIATES L.L.C.
                     A NEW JERSEY LIMITED LIABILITY COMPANY

                  This OPERATING AGREEMENT OF PARSIPPANY OFFICE
ASSOCIATES L.L.C., a New Jersey limited liability company, (this "Agreement") is
made and entered into as of December 28,1999, by and between MACK-CALI REALTY,
L.P., a Delaware limited partnership ("MC") as the Managing Member (as the
Managing Member may be changed or replaced from time to time hereunder, the
"Managing Member") and SLAB INVESTMENTS HOLDING, INC., a Delaware corporation
("SLAB") as a Member (each of MC and SLAB is sometimes referred to herein as a
"Member" and collectively as the "Members").

                  1. FORMATION/GOVERNING LAW. This limited liability company
("Company") shall be formed and established as a limited liability company as
of the date hereof, pursuant to the provisions of the New Jersey Limited
Liability Company Law, NJSA 42 ET SEQ. (the "Act"). This Agreement shall be
governed by New Jersey law.

                  2. NAME. The name of the Company shall be PARSIPPANY OFFICE
ASSOCIATES L.L.C.

                  3. CERTIFICATES. On December 17, 1999, a Certificate of
Formation (the "Certificate") was filed in the Office of the Secretary of State
of New Jersey.

                  4. PRINCIPAL PLACE OF BUSINESS. The principal place of
business of the Company shall be at c/o Mack-Cali Realty Corporation, 11
Commerce Drive, Cranford, New Jersey 07016, or at such other place(s) in New
York or New Jersey as may be designated from time to time by the Managing
Member.

                  5. OFFICE AND AGENTS. The name and address of the registered
agent for service of process on the Company in the State of New Jersey shall be
Corporation Service Company, 830 Bear Tavern Road, West Trenton, New Jersey
08628. The Managing Member in its reasonable discretion and upon notice to the
other Member may change the agent specified in this Section 5 of this Agreement.

                  6. PURPOSES OF COMPANY. The purpose of the Company shall be to
acquire for investment purposes, and own, finance, refinance, sell, assign or
otherwise dispose of, the investment entities described in Section 9 below
(each, together with any other entity that is owned by the Company, an
"Investment Entity" and collectively, the "Investment Entities"), owning the
Properties (as

<PAGE>

defined in Section 9 below) and other assets related thereto. The purposes of
the Company shall include any and all other general business activities
incidental or reasonably related to the foregoing.

                  7. TERM. The term of the Company shall begin on the date the
Certificate is filed with the Secretary of State of New Jersey and shall
continue until December 31, 2029, unless the term of the Company is extended by
an amendment to this Agreement so stating and executed by each of the Members,
or unless the Company is sooner terminated or liquidated in accordance with the
provisions of the Act or this Agreement. The Company's business shall be
terminated, and the Company shall be liquidated, upon the bankruptcy of any
Member unless a majority in interest of the remaining Members elect in writing,
by notice to all Members given within ninety (90) days thereafter, to
reconstitute the Company and continue its business, which right of election is
hereby granted to them. Notwithstanding any provision to the contrary contained
herein, the Company's business shall be terminated, and the Company shall be
liquidated, in the event the Company no longer owns any interest in any
Investment Entity or all Investment Entities have disposed of the Properties and
no longer own any interest therein.

                  8. RELATIONSHIP OF PARTIES. This Agreement shall be construed
and deemed to create a limited liability company. Nothing herein contained shall
be considered to constitute any Member as the agent of any other Member, except
as may be specifically authorized and provided for herein.

                  9. CAPITAL CONTRIBUTIONS. At the closing ("Closing") under the
Purchase Agreement (as defined below in this Section 9), the Members shall
contribute, as their respective capital contributions ("Capital Contributions")
to the Company, the amounts set forth on Exhibit A (in the respective
proportions stated on Exhibit A) in connection with the Company's purchase of
100% of the membership interests in the following Investment Entities pursuant
to that certain Agreement of Sale and Purchase dated as of even date herewith
("Purchase Agreement"): Mack- Cali Campus Realty L.L.C, a New Jersey limited
liability company, and Mack-Cali Morris Realty L.L.C., a New Jersey limited
liability company. Such Investment Entities own the parcels of real property and
the leasehold interest described on Exhibit B attached hereto (each such real
property, together with any related leasehold interest, a "Property" and
collectively the "Properties", including all improvements thereon and the
personal property related thereto that is owned by the applicable Investment
Entity). Each Member hereby acknowledges and agrees that all costs and expenses
(including without limitation, attorneys' fees and costs) incurred by such
Member in connection with this Agreement and (solely as a Member of the Company)
the Purchase Agreement, the Management Agreement and the Asset Management
Agreement (as such terms are defined in Section 11) shall be borne by such
Member.

        Except as specifically set forth in this Section 9 or elsewhere in this
Agreement or agreed to separately in writing by all of the Members or required
by law, (i) none of the Members shall be required or entitled to make any
additional capital contributions to the Company, to make loans to the Company,
to provide any financing to the Company, or to cause any financing to be made
available to

                                       2
<PAGE>

the Company, (ii) the Members shall not have any further liability to contribute
money to or in respect of the liabilities or obligations of the Company, and
(iii) the Members shall not be liable for any liabilities of the Company. All
additional capital contributions will require the approval of both Members
(which approval may be withheld in each Member's sole and absolute discretion)
and shall be funded by the Members PARI PASSU in their respective Funding
Proportions shown on Exhibit A. In the event the Managing Member determines that
additional funds are necessary for ordinary and reasonable business purposes of
the Company, any Investment Entity or any Property but additional capital
contribution for such funds is not approved by both Members and the Managing
Member decides to lend such funds (which the Managing Member may but shall not
be required to do), the Managing Member shall provide notice to the other Member
that the Managing Member intends to lend such funds to the Company as a loan.
Within 5 days after receiving such notice from the Managing Member, the other
Member shall have the right to participate in such loan in an amount equal to
such member's respective Funding Proportion multiplied by the amount of such
funds by providing notice thereof (setting forth the percentage of such funds
the other Member elects to lend) to the Managing Member. Failure to provide such
notice by the other Member to the Managing Member shall be deemed an election by
the other Member not to participate, and the Managing Member shall fund the
entire loan within 5 days after the other Member's failure to provide such
notice. If such a notice is timely given by the other Member to the Managing
Member, within 5 days thereafter, the other Member shall fund the percentage of
the loan set forth in such notice and the Managing Member shall fund the
remainder of the loan. The loans made by the Members to the Company in
accordance with this paragraph shall accrue interest at LIBOR plus 200 basis
points per annum, compounded monthly, from the date such loans are made until
repaid by the Company.

         As used in this Agreement, "LIBOR" shall mean, with respect to each
LIBOR Reference Period, the rate (expressed as a percentage per annum) for
deposits in U.S. dollars, for a one-month period, that appears on Telerate Page
3750 (or the successor thereto) as of 11:00 a.m., London, England time, on the
related LIBOR Determination Date. If such rate does not appear on Telerate Page
3750 as of 11:00 a.m., London, England time, on such LIBOR Determination Date,
LIBOR shall the arithmetic mean of the offered rates (expressed as a percentage
per annum) for deposits in U.S. dollars for a one-month period that appear on
the Reuters Screen LIBOR Page as of 11:00 a.m., London, England time, on such
LIBOR Determination Date, if at least two such offered rates so appear. If fewer
than two such offered rates appear on the Reuters Screen LIBOR Page as of 11:00
a.m., London, England time, on such LIBOR Determination Date, SLAB shall request
the principal London, England office of each of any four major reference banks
in the London interbank market selected by SLAB to provide such bank's offered
quotation (expressed as a percentage per annum) to prime banks in the London
interbank market for deposits in U.S. dollars for a one-month period as of 11:00
a.m., London, England time, on such LIBOR Determination Date for amounts
approximately equal to SLAB Return Amount. If at least two such offered
quotations are so provided, LIBOR shall be the arithmetic mean of such
quotations. If fewer than two such offered quotations are so provided, SLAB
shall request each of any three major banks in New York City selected by SLAB to
provide such bank's rate (expressed as a percentage per annum) for loans in U.S.
dollars to leading European

                                       3
<PAGE>

banks for a one-month period as of approximately 11:00 a.m., New York City time,
on the applicable LIBOR Determination Date for amounts approximately equal to
the SLAB Return Amount. If at least two such rates are so provided, LIBOR shall
be the arithmetic mean of such rates. If fewer than two such rates are so
provided, then LIBOR for the applicable LIBOR Reference Period shall be LIBOR as
in effect for the next preceding LIBOR Reference Period. LIBOR shall be
determined in accordance with this paragraph by SLAB or its designee.
Notwithstanding the foregoing, LIBOR for the period commencing on the date
hereof and ending January 5, 2000 shall be 6.49% per annum.

         As used herein, the term "LIBOR Business Day" shall mean any Business
Day on which commercial banks in the City of London, England, are open for
interbank or foreign exchange transactions.

         As used herein, the term "LIBOR Determination Date" shall mean, with
respect to any LIBOR Reference Period, the date that is two (2) LIBOR Business
Days prior to the first day of such LIBOR Reference Period.

         As used herein, the term "LIBOR Reference Period" shall mean, (i)
initially, the period commencing on the date of this Agreement for the
Guaranteed Payments and the loan funding date for the Member loans and ending on
the first occurring fifth (5th) day of a calendar month thereafter, and (ii)
thereafter, a period commencing on the sixth (6th) day of such calendar month
and ending on the fifth (5th) day of the following calendar month.

                  10. CAPITAL ACCOUNTS. An individual capital account shall be
maintained for each Member, and tax allocations made pursuant to this Agreement
shall be made, in accordance with applicable Treasury Regulations under Section
704 of the Internal Revenue Code of 1986, as amended ("Code"). The Managing
Member shall be the "Tax Matters Partner" of the Company and shall be
responsible for filing the tax returns of the Company on a timely basis (but no
later than May 15 of each year). The Managing Member shall be responsible for
complying with any and all reporting requirements on behalf of the Company,
including those set forth on Exhibit D. All tax decisions, tax returns and
settlements with taxing authorities shall be subject to the reasonable approval
of both Members.

                  11. POWERS AND RESPONSIBILITIES OF THE MEMBERS; PROPERTY
MANAGEMENT; ASSET MANAGEMENT FEE; SALE RIGHTS; INDEMNITY.

         (a) Subject to the approval rights of the Members under Sections 11(b)
and 11(c) and the sale and financing rights of the Members under Section 11(d),
and except as otherwise provided herein, the then Managing Member shall have all
of the rights, power and authority of a manager in a limited liability company
under the Act and the management and operation of the affairs, activities and
business of the Company shall be vested exclusively in the Managing Member. The
Members hereby authorize the Managing Member to execute all documents and to
take all actions as may be necessary or

                                       4
<PAGE>

desirable on behalf of the Company which are consistent with the Company's
purposes, any major decisions approved by the Members under Section 11(b) or
11(c), and any sale or financing decisions made by the applicable Member under
Section 11(d). The Members hereby approve the budgets attached hereto as Exhibit
E with respect to the Properties (the "Current Budgets") and, subject to the
approval rights and the restrictions contained elsewhere in this Agreement, the
Managing Member may cause the Investment Entities to make the expenditures
described in the Current Budgets (as the same may be modified from time to time
by the Managing Member in the exercise of its commercially reasonable business
judgment, which modifications, in each instance and in the aggregate, shall not
increase the total expenses set forth in the Current Budgets by more than 10% to
pay expenditures reasonably required with respect to the Property and provided
that such increased expenditures do not prevent the Guaranteed Payments from
being made to SLAB under Section 13(c)(1)). The Members also hereby approve that
certain Leasing and Management Agreement dated as of December 28, 1999
(collectively, the "Management Agreement") with respect to the Properties and
that certain Asset Management Agreement dated as of December 28, 1999 ("Asset
Management Agreement") with respect to the Investment Entities and the
Properties.

         MC shall be the Managing Member until the earlier to occur of the
following: (i) MC is removed as the Managing Member under Section 11(e); or (ii)
a majority in Residual Percentages (as set forth in Exhibit A) of the Members
elects to remove MC as the Managing Member by providing written notice thereof
to MC at any time after January 2, 2001.

         (b) Subject to the provisions of Section 11(d) but notwithstanding any
other provision to the contrary herein, so long as MC is the Managing Member,
the following actions and matters are major decisions requiring the reasonable
(except as otherwise provided) written approval of the Members (whether in
advance in a business plan, budget, or other pre-approval, or at the time of the
action in question, as the case may be):

                  (i) Entering into, approving, terminating or modifying to any
         material extent the Management Agreement or the Asset Management
         Agreement (SLAB may withhold its approval to the foregoing actions and
         matters in this clause (i) in its sole and absolute discretion), or
         selecting any architect, engineer, broker, leasing agent, property
         manager, marketing or other consultant, contractor or sales agent for
         any Property, any Investment Entity or the Company who are not
         currently providing services to the Investment Entities or the Company
         or in connection with the Properties in the ordinary course of
         business;

                  (ii) Terminating or modifying to any material extent the
         insurance policies currently maintained by the Investment Entities with
         respect to the Properties);

                  (iii) Terminating any leases at any Property (except by reason
         of a material breach of a tenant thereunder), or entering into,
         approving or modifying to any material extent any lease at any
         Property, in each case which is for either more than 25% of the total
         leaseable space of

                                       5
<PAGE>

         the building at issue or more than 40,000 square feet of leaseable
         space. All new leases shall be on such terms and conditions which are
         not less favorable to the landlord than those of similar leases entered
         into at arm's length between unrelated parties for comparable leases of
         space in the area where the Properties are located;

                  (iv) Causing or permitting the Company or any Investment
         Entity to file for bankruptcy or other relief from creditors, including
         without limitation, an assignment for the benefit of creditors, an
         admission in writing by any such entity of its inability to pay its
         debts generally as they become due, causing the Company, a Member's
         membership interest in the Company, any Investment Entity, the
         Company's membership interest in any Investment Entity, or any Property
         or any part thereof or interest therein to be subject to the authority
         of any trustee, custodian or receiver or to be subject to any
         proceeding for bankruptcy, insolvency, reorganization, arrangement,
         readjustment of debt, relief of debtors, dissolution or liquidation or
         similar proceedings (collectively and singly, "Bankruptcy Action")
         (SLAB may withhold its approval to all actions and matters in this
         clause (iv) in its sole and absolute discretion);

                  (v) Making any distributions except as permitted hereunder, or
         establishing reserves with respect to a Property in excess of 10% of
         the annual cash flow from such Property or releasing funds therefrom
         except in accordance with this Agreement and the reasonable needs of
         the Company's business (SLAB may withhold its approval to all actions
         and matters in this clause (v) in its sole and absolute discretion);

                  (vi) Dissolving, terminating or liquidating the Company or any
         Investment Entity, or redeeming any interest of any Member, except as
         provided herein (SLAB may withhold its approval to all actions and
         matters in this clause (vi) in its sole and absolute discretion);

                  (vii) Entering into, approving, terminating or modifying the
         terms of any contracts, agreements, leases and other undertakings with
         any Member or its affiliates (SLAB may withhold its approval to the
         foregoing actions and matters in this clause (vii) in its sole and
         absolute discretion); PROVIDED, HOWEVER, that entering into, approving,
         terminating or modifying to any material extent any service contracts
         and other contracts and agreements (not otherwise specifically
         addressed herein) with non-affiliates shall be permitted without any
         Member approval so long as such contracts are entered into for
         reasonable business purposes of the Company or the Investment Entities
         on bona fide market terms and conditions for comparable goods or
         services and for the area where the Properties are located.
         Notwithstanding anything to the contrary contained in this Agreement,
         to the extent any affiliate of MC is now or hereafter becomes a party
         to any contract, agreement, lease or other undertaking entered into
         with the Company or any Investment Entity (including without
         limitation, the Purchase Agreement, the post-closing agreements in
         connection therewith, the Management Agreement and the Asset Management
         Agreement), SLAB, acting alone, shall have the exclusive right and
         authority on behalf of the Company (A) to exercise termination rights
         in accordance with the terms of such

                                       6
<PAGE>

         document, (B) to enforce and defend the Company's or the applicable
         Investment Entity's rights (including without limitation, right to seek
         damages for breach of representations and warranties and enforce
         indemnities) under such document (including by prosecution or defense
         of any proceeding or action that it deems necessary or appropriate),
         and (C) to retain Company or Investment Entity counsel of its choosing
         in connection with the foregoing at MC's expense. MC shall disclose to
         SLAB in writing whether any party to a proposed contract, agreement,
         lease or other undertaking to be entered into with the Company or any
         Investment Entity is an affiliate of MC promptly after MC becomes aware
         of such relationship and such proposed contract, agreement, lease or
         other undertaking, and, in any event (and without limiting the
         foregoing), prior to the Company's or such Investment Entity's
         execution of the same. As used in this Agreement, an "affiliate" of a
         Member shall mean any other individual, corporation, limited liability
         company, partnership, trust, association or other entity or
         organization directly or indirectly controlling, controlled by or under
         common control with such Member. The term "control" or derivatives of
         same shall mean direct or indirect ownership of more than 50% and/or
         possession of the power to direct the management policies;

                  (viii) Acquiring, selling, conveying, exchanging,
         hypothecating, pledging, encumbering or otherwise transferring all or
         any portion of or any interest in any Property or Investment Entity
         (other than pursuant to Section 11(d)), or in any other real property
         now or hereafter owned by the Company or any Investment Entity (SLAB
         may withhold its approval to all actions and matters in this clause
         (viii) in its sole and absolute discretion);

                  (ix) Performing, or causing to be performed, any construction,
         repair or rebuilding of any improvements at the Properties (except in
         an emergency to correct or alleviate any unsafe conditions or except as
         may be required under any tenant leases); PROVIDED, HOWEVER, that SLAB
         may withhold its approval in its sole and absolute discretion on
         decisions to repair or rebuild after a casualty or partial condemnation
         costing more than $250,000 or to construct any new buildings or
         increase the size of any existing buildings. If the Members agree to
         repair or rebuild, any insurance or condemnation proceeds of more than
         $250,000 shall be placed in an escrow and the Members shall reasonably
         agree upon the terms and conditions for the release of the proceeds
         from the escrow in connection with such repair or rebuilding. Any
         insurance or condemnation proceeds not used to repair or rebuild shall
         be distributed to the Members pursuant to Section 13;

                  (x) Except as otherwise provided herein, incurring any
         indebtedness on behalf of the Company or any Investment Entity (except
         that the Members hereby approve any reasonable, ordinary and necessary
         trade payables incurred in the ordinary course of business to
         non-affiliates of the Managing Member, and payments made, pursuant to
         non-affiliate contracts which are in effect at the Closing or which are
         approved by the Members); making, executing or delivering on behalf of
         the Company or any Investment Entity any indemnity bond or surety bond;
         lending funds belonging to the Company or any Investment Entity to any
         person

                                       7
<PAGE>

         or entity, or extending any person, firm or corporation credit on
         behalf of the Company or any Investment Entity; obligating the Company,
         another Member or any Investment Entity as a surety, guarantor or
         accommodation party to any obligation, except by endorsing checks for
         deposit to the Company's or an Investment Entity's accounts in the
         ordinary course of business, or granting or permitting any lien or
         encumbrance on any Property other than mechanics' liens for work
         performed at the Properties (SLAB may withhold its approval to all
         actions and matters in this clause (x) in its sole and absolute
         discretion);

                  (xi) Confessing a judgment against the Company or any
         Investment Entity; settling or adjusting any claims (including without
         limitation, insurance claims) against or of the Company or any
         Investment Entity; consenting to any condemnation awards or
         settlements; or commencing, defending or discontinuing any legal
         actions or proceedings involving the Company or any Investment Entity,
         to the extent such judgment, claims, awards, settlements, actions or
         proceedings have an aggregate amount in controversy exceeding $250,000
         (SLAB may withhold its approval in its sole and absolute discretion
         with respect to condemnation awards or settlements in excess of 10% of
         the cost of the Property at issue and with respect to any other actions
         or matters in this clause (xi) having an aggregate amount in
         controversy exceeding $1,000,000);

                  (xii) Submitting binding proposals to, or entering into,
         approving, terminating or modifying binding agreements with,
         governmental officials relating to zoning, subdivision, environmental
         or other land use or entitlement matters (SLAB may withhold its
         approval to the foregoing actions and matters in this clause (xii) in
         its sole and absolute discretion; PROVIDED, HOWEVER, that SLAB shall
         have only reasonable approval rights with respect to binding agreements
         regarding zoning and entitlement matters related to tenant improvements
         at the Properties or to landscaping, utility easements, buffers and
         other similar items and conditions required by the Towns of Hanover or
         Parsippany, New Jersey, in connection with obtaining development
         approvals for adjacent land so long as the Properties are not
         materially adversely affected thereby; PROVIDED, FURTHER, that any
         actions taken in order to comply with the applicable zoning and other
         land use requirements shall not require any approval of SLAB);

                  (xiii) Possessing, assigning or using funds or other property
         of the Company or any Investment Entity for other than a Company or
         Investment Entity purpose (SLAB may withhold its approval to the
         actions and matters in this clause (xiii) in its sole and absolute
         discretion);

                  (xiv) Partitioning all or any portion of any Property, or
         filing any complaint or instituting any proceeding at law or in equity
         seeking such partition (SLAB may withhold its approval to the actions
         and matters in this clause (xiv) in its sole and absolute discretion);

                  (xv) Purchasing any assets or equipment on behalf of or in the
         name of the Company or any Investment Entity (except in connection with
         transfers among Investment Entities under

                                       8
<PAGE>

         Section 11(d)) other than those required in the ordinary course of the
         Company's or such Investment Entity's business (SLAB may withhold its
         approval to the actions and matters in this clause (xv) in its sole and
         absolute discretion);

                  (xvi) Except as otherwise provided in Section 11(d) of this
         Agreement, entering into, approving, terminating or modifying to any
         material extent any loan document or loan instrument to which the
         Company or any Investment Entity is or will be a party or the Company,
         any Investment Entity or any Property is or will be bound or subject
         to, or giving any consent, approval or waiver, or making any
         determination or stipulation, on behalf of the Company or any
         Investment Entity under any such loan document or instrument (SLAB may
         withhold its approval to the actions and matters in this clause (xvi)
         in its sole and absolute discretion);

                  (xvii) Admitting any new Members or causing or permitting any
         merger or restructuring of the Company or the Investment Entities
         (other than pursuant to Section 11(d)) (SLAB may withhold its approval
         to the actions and matters in this clause (xvii) in its sole and
         absolute discretion);

                  (xviii) Modifying or terminating this Agreement or any other
         Company organizational documents or any organizational documents of any
         Investment Entity (SLAB may withhold its approval to the actions and
         matters in this clause (xviii) in its sole and absolute discretion);

                  (xix) Changing the nature of business or business purpose of
         the Company or any Investment Entity (SLAB may withhold its approval to
         the actions and matters in this clause (xix) in its sole and absolute
         discretion);

                  (xx) Making any expenditures not in compliance with the
         Current Budgets, except as the Current Budgets may be modified pursuant
         to Section 11(a) above (SLAB may withhold its approval to the actions
         and matters in this clause (xx) in its sole and absolute discretion);

                  (xxi) Approving the acceptability of any post-closing
         deliveries under the Purchase Agreement and post-closing adjustments
         under the Purchase Agreement; and

                  (xxii) Any other matter that requires the approval of both
         Members under this Agreement (SLAB may withhold its approval to all
         such matters in its sole and absolute discretion unless indicated
         otherwise).

         No amount shall be expended by any Member for a major decision without
first obtaining the approval of the Members (to the extent such approval is
required hereunder at such time). However, the Managing Member may expend
reasonable amounts in response to an emergency (which amounts shall be
reimbursed by the Company or the Investment Entities, as applicable). Failure to
disapprove in writing by a Member within five (5) business days (unless another
time period is specified in this

                                       9
<PAGE>

Agreement) after receiving a written request for approval from the other Member
under this Agreement shall be deemed an approval of the action or matter in the
request, provided that such request states conspicuously that failure to approve
within such time period constitutes such Member's approval. Any request for
approval herein shall describe the action or matter to be approved with
sufficient specificity to permit a reply, and any approval or disapproval
thereof shall set forth the reasons therefor with sufficient specificity to
permit a reply.

         (c) Subject to the provisions of Section 11(d) but notwithstanding any
other provision to the contrary herein, while MC is not the Managing Member, the
following actions and matters are major decisions requiring the written approval
of MC, which MC may withhold in its sole and absolute discretion:

                  (i) Causing or permitting the Company or any Investment Entity
         to file for bankruptcy or other relief from creditors, including
         without limitation, an assignment for the benefit of creditors, an
         admission in writing by any such entity of its inability to pay its
         debts generally as they become due, causing the Company, a Member's
         membership interest in the Company, any Investment Entity, the
         Company's membership interest in any Investment Entity, or any Property
         or any part thereof or interest therein to be subject to the authority
         of any trustee, custodian or receiver or to be subject to any
         proceeding for bankruptcy, insolvency, reorganization, arrangement,
         readjustment of debt, relief of debtors, dissolution or liquidation or
         similar proceedings;

                  (ii) Dissolving, terminating or liquidating the Company or any
         Investment Entity, or redeeming any interest of any Member, except as
         provided herein;

                  (iii) Entering into, approving, terminating or modifying to
         any material extent the terms of contracts, agreements, leases or other
         undertakings with any affiliates of SLAB. Notwithstanding anything to
         the contrary contained in this Agreement, to the extent any affiliate
         of SLAB is now or hereafter becomes a party to any contract, agreement,
         lease or other undertaking entered into with the Company or any
         Investment Entity, MC, acting alone, shall have the exclusive right and
         authority on behalf of the Company (A) to exercise termination rights
         in accordance with the terms of such document, (B) to enforce and
         defend the Company's or the applicable Investment Entity's rights under
         such document (including by prosecution or defense of any proceeding or
         action that it deems necessary or appropriate), and (C) to retain
         Company or Investment Entity counsel of its choosing in connection with
         the foregoing at SLAB's expense. SLAB shall disclose to MC in writing
         whether any party to a proposed contract, agreement, lease or other
         undertaking to be entered into with the Company or any Investment
         Entity is an affiliate of SLAB promptly after SLAB becomes aware of
         such relationship and such proposed contract, agreement, lease or other
         undertaking, and, in any event (and without limiting the foregoing),
         prior to the Company's or such Investment Entity's execution of the
         same;

                                       10
<PAGE>

                  (iv) Possessing, assigning or using funds or other property of
         the Company or any Investment Entity for other than a Company or
         Investment Entity purpose;

                  (v) Admitting any new Members or causing or permitting any
         merger or restructuring of the Company or the Investment Entities
         (other than pursuant to Section 11(d));

                  (vi) Modifying or terminating this Agreement or any other
         Company organizational documents or any organizational documents of any
         Investment Entity; and

                  (vii) Changing the nature of business or business purpose of
         the Company or any Investment Entity.

         (d) Notwithstanding any provision to the contrary contained herein
(including without limitation, Section 11(b) hereof), the Members shall have the
following rights:

                  (i) From the date of this Agreement and until January 2, 2001
         (the "Outside Closing Date"), MC shall have the right, in MC's sole and
         absolute discretion without the other Member's approval being required,
         to negotiate, enter into and perform under, on behalf of the Company
         and/or the Investment Entities, one or more agreements with one or more
         parties (including MC's affiliates) for the sale, financing or
         refinancing of one or more Properties and/or Investment Entities (or
         the ownership interests therein) on any terms and conditions, PROVIDED
         that: (A) any such transaction closes on or prior to the Outside
         Closing Date; (B) all accrued and unpaid Guaranteed Payments to SLAB
         under Section 13(c)(1) must have been made; (C) in the case of sale, a
         financing or refinancing of all of the Properties or interests therein
         not previously sold, financed or refinanced under this Section 11(d)
         (the "Remaining Properties"), the cash sale price received by the
         Company and the Investment Entities at the closing thereunder or the
         loan amount received by Company and the Investment Entities must at
         least be equal to an amount that will result in SLAB receiving, from
         proceeds of the transaction and previous transactions, the sum of the
         amounts described in Sections 13(b)(2)(i), 13(b)(2)(ii), and 13(c)(1)
         hereof (the "SLAB Return Amount"); (D) in the case of sale, a financing
         or refinancing of less than all of the Remaining Properties, the cash
         sale price received by the Company and the Investment Entities at the
         closing thereunder or the loan amount received by Company and the
         Investment Entities must at least be equal to an amount that will
         result in SLAB receiving (in addition to all accrued and unpaid
         Guaranteed Payments), from proceeds of the transaction and
         distributions under Section 13(b)(i), 102% of the amount(s) set forth
         for the Property(ies) at issue in Exhibit C; (E) in the case of sale, a
         financing or refinancing of less than all of the Remaining Properties,
         the Property(ies) to be sold, financed or refinanced must be owned by a
         separate Investment Entity(ies) created and maintained as a limited
         liability company, and the Company and the other Investment Entities
         must not be subject to any personal liability under such sale,
         financing or refinancing (and no other assets of the Company or any
         Investment Entity except those that are the subject of such sale,
         financing or refinancing

                                       11
<PAGE>

         shall be subject to the claims of the lender or purchaser in such
         transaction, whether for debt service, damages or any other amounts),
         and there must not then exist any monetary breach or any uncured
         material non-monetary breach by MC hereunder; and (F) in the case of a
         sale, financing or refinancing of less than all of the Remaining
         Properties, there must not then exist any uncured monetary or material
         non-monetary breach by MC hereunder (except that with respect to
         Section 11(f)(xix) hereof (which shall be determined without regard to
         whether MC used reasonable commercial efforts and without regard to
         materiality), the seller under the Purchase Agreement must also have
         failed to make the deliveries as required by Sections 8.4(c), 8.4(d)
         and 8.4(e) of the Purchase Agreement) and there must not have been a
         material adverse change with respect to any of the other Remaining
         Properties (including without limitation, the value, cash flow or
         tenancy at any such Property). In transactions described in the
         immediately preceding clause (F), MC shall provide written notice of
         same to SLAB at least fifteen (15) business days prior to entering into
         a binding agreement with respect to such transaction and SLAB shall
         have the right to determine, in its sole discretion, whether there has
         been a material adverse change with respect to any of the other
         Remaining Properties. SLAB's failure to provide written notice of such
         determination within fifteen (15) business days after its receipt of
         such notice from MC shall be deemed to be SLAB's determination that
         there has been no such material adverse change. Except as otherwise
         provided in this Section 11(d)(i), until the Outside Closing Date, MC
         shall have the right to perform any act, or execute and deliver any
         document or instrument, as may be reasonably necessary or appropriate
         in connection with such transactions without any other Member's
         approval being required. Notwithstanding the last sentence of Section
         11(b)(ix), the purchaser of a Property or interests therein shall be
         entitled to receive an assignment of any casualty or condemnation
         proceeds allocable to such Property to the extent not theretofore used
         to repair, rebuild or replace the Property (and for which the purchaser
         is not otherwise receiving an appropriate reduction in the purchase
         price).

                  (ii) At any time (A) after the Outside Closing Date, if SLAB
         has not then received the SLAB Return Amount, or (B) MC is in breach of
         Section 11(f)(xix) hereof (which shall be determined without regard to
         whether MC used reasonable commercial efforts and without regard to
         materiality) AND the seller under the Purchase Agreement has failed to
         make the deliveries as required by Sections 8.4(c), 8.4(d) and 8.4(e)
         of the Purchase Agreement, a majority in Residual Percentages of the
         Members (which term, as used herein, shall mean the Members owning
         greater than 50% of all Residual Percentages in the Company) shall have
         the right, in its sole and absolute discretion without the approval of
         any other Member being required, to negotiate, enter into and perform
         under, on behalf of the Company and/or the Investment Entities one or
         more agreements with one or more parties (including affiliates of the
         electing Members) for the sale, financing, refinancing or
         securitization of one or more Properties and/or Investment Entities (or
         the ownership interests therein) on any terms and conditions; PROVIDED,
         HOWEVER, that MC shall have the right to purchase the assets being sold
         or provide such financing or refinancing (as applicable) on the same
         terms and conditions, which right MC must exercise by providing written
         notice thereof to SLAB within 20 days after receiving

                                       12
<PAGE>

         written notice from SLAB setting forth such terms and conditions. MC's
         failure to provide such notice timely shall be deemed MC's election not
         to exercise such right. If MC timely exercise such right, the closing
         shall occur within 30 days thereafter. If MC has not been removed as
         the Managing Member, MC shall cooperate in connection with the
         transactions contemplated under this clause (ii). In connection with
         the sale, financing, refinancing or securitization transactions under
         this Section 11(d)(ii), a majority in Residual Percentages of the
         Members shall (1) have the right to perform any act, or execute and
         deliver any document or instrument, as may be reasonably necessary or
         appropriate in connection with such transactions without any other
         Member's approval being required and (2) cause all costs of the
         foregoing, including without limitation the following due diligence
         items, if required to be provided by the Company or the Investment
         Entities in connection with any such transaction, to be paid at the
         Company expense: engineering reports, Phase I environmental reports,
         appraisal, title reports, searches and endorsements, surveys, and
         certificates of occupancy.

                  (iii) The proceeds (net of transaction costs and expenses)
         from any sale, condemnation, casualty, financing, refinancing or
         securitization described in paragraphs (i) and (ii) of this Section
         11(d) shall be distributed or paid by the Company as provided in this
         Agreement.

                  (iv) In connection with the sale, financing, refinancing or
         securitization transactions described in paragraphs (i) and (ii) of
         this Section 11(d), the Member with the right to cause such
         transactions to occur shall have the right, in such Member's sole and
         absolute discretion without the other Member's approval being required,
         to form one or more additional single-member Investment Entities owned
         by the Company and to cause the existing Investment Entities to
         transfer one or more Properties which are the subject of such sale,
         financing, refinancing or securitization to such additional Investment
         Entities and to transfer the Company's interest in such additional
         Investment Entities or the Property(ies) owned thereby. Except as
         otherwise provided in Section 11(d)(i), such Member shall give written
         notice of any transaction described in this Section 11(d) to the other
         Member at least ten (10) days prior to causing the Company to enter
         into such transaction.

         (e) No Member (including any Managing Member) shall be liable,
responsible or accountable in damages or otherwise to the other Member or the
Company or any Investment Entity for any act or omission of such Member on
behalf of the Company, except for fraud, gross negligence or material breach of
this Agreement. Except as provided in this Section 11(e), the Company shall
indemnify and hold harmless each Member (including any Managing Member) and its
affiliates from and against any obligations, damages, claims, liabilities,
losses, costs or expenses, including reasonable attorneys' fees and costs
(collectively, "Claims"), incurred in connection with or arising out of such
Member acting as a Member or on behalf of the Company in accordance with this
Agreement.

                                       13
<PAGE>

         Each Member shall be liable to the other Member for such other Member's
actual damages to the extent caused by any fraud, gross negligence or material
breach of this Agreement by the liable Member and not caused by any fraud, gross
negligence or material breach of this Agreement by the other Member. As used in
the immediately preceding sentence of this paragraph, the term "actual damages"
shall: (1) include, without limitation, the costs (including reasonable
attorneys' fees and costs) of enforcing the rights of a Member under this
Agreement and collecting such damages; and (2) include, without limitation, any
and all kinds of damages actually paid by such other Member to unaffiliated
third parties (including any consequential, speculative, punitive or special
damages actually paid by such other Member to unaffiliated third parties); but
(3) exclude any other consequential, speculative, punitive or special damages.
MC hereby agrees to indemnify and hold harmless SLAB and its affiliates from and
against any third-party Claims to the extent caused by MC's fraud, gross
negligence or material breach of this Agreement and not by SLAB's fraud, gross
negligence or material breach of this Agreement. Any amounts payable under this
paragraph shall be made immediately upon written demand therefor and shall
accrue interest from the date of such demand until paid at the lesser of fifteen
percent (15%) per annum or the highest rate permitted by applicable law.

         Without limiting the foregoing, upon the occurrence of any of the
following, (A) SLAB shall have the right to remove MC as the Managing Member of
the Company, (B) any distributions to MC under Section 13(b)(2) (other than its
Guaranteed Payments) shall be subordinated to any and all distributions and
payments to SLAB hereunder, and (C) SLAB shall have the right to institute
reasonable cash management procedures pursuant to which tenants will make
payments under their leases directly to a lock box account and SLAB will control
all disbursements therefrom:

                  (i) fraud by MC with respect to the Company, any Investment
         Entity or any Property or with respect to any transactions contemplated
         hereunder;

                  (ii) any gross negligence on the part of MC with respect to
         any of its duties and obligations hereunder which is not cured to
         SLAB's reasonable satisfaction within 45 days after receiving written
         notice of such gross negligence from SLAB;

                  (iii) failure by MC to use any available cash to make the
         Guaranteed Payments under Section 13(c)(1) for three (3) consecutive
         months;

                  (iv) any monetary default by MC under this Agreement at any
         time;

                  (v) any representation or warranty made by seller in the
         Purchase Agreement (or in any other documents delivered to the Company
         thereunder) or made by MC in this Agreement shall have been false or
         misleading in any material respect when made and MC fails to cure (to
         SLAB's reasonable satisfaction) such breach of representation or
         warranty within forty five (45) days after MC's receipt of written
         notice of such breach from SLAB;

                                       14
<PAGE>

                  (vi) except as provided in clause (ix) below of this Section,
         material breach of any non-monetary covenants set forth Section 11(f)
         (determined without regard to whether MC used its reasonable commercial
         efforts in connection therewith) or a material breach of any other
         non-monetary provisions hereof by MC and MC's failure to cure (to
         SLAB's reasonable satisfaction) such breach within forty five (45) days
         after MC's receipt of written notice of such breach from SLAB;

                  (vii) any monetary breach or material non-monetary breach of
         the Management Agreement by the property manager or the Asset
         Management Agreement by the asset manager;

                  (viii) any Bankruptcy Action with respect to MC; and

                  (ix) breach of Section 11(f)(xix) (determined without regard
         to whether MC used its reasonable commercial efforts in connection
         therewith).

         Any notice alleging a breach or gross negligence referenced above shall
specify the breach or gross negligence with sufficient particularity to permit
the cure, and any such cure shall be at the breaching Member's expense. The
non-breaching Member may effect such cure at the breaching Member's expense if
the breaching Member shall fail to effect such cure timely. If MC is removed (or
if a majority in Residual Percentages of the Members is entitled to remove MC)
as the Managing Member hereunder, SLAB shall have the right to terminate all
agreements and contracts between the Company and any affiliates of MC (including
without limitation, the Asset Management Agreement and the Management
Agreement).

         (f) So long as MC is the Managing Member hereunder, MC shall use
reasonable commercial efforts to:

                  (i) not take any actions that require SLAB's approval under
         Section 11(b) without first obtaining such approval or otherwise in
         accordance with Section 11(b);

                  (ii) not cause or permit any Bankruptcy Action;

                  (iii) not cause or permit the Company or the Investment
         Entities to own any encumbered asset other than pursuant to Section
         11(d) (financing right);

                  (iv) not cause or permit the Company or the Investment
         Entities to engage in any business other than the ownership, management
         and operation of the Properties and the Investment Entities;

                                       15
<PAGE>

                  (v) do all things necessary to preserve the Company's and the
         Investment Entities' existence and limited liability company
         formalities;

                  (vi) conduct and operate the business of the Company and the
         Investment Entities as presently conducted and operated in material
         respects;

                  (vii) not cause or permit the Company or the Investment
         Entities to be responsible for the debts or obligations of any person
         or entity other than the Company or the Investment Entities;

                  (viii) provide prompt written notice to SLAB of any
         litigation, bankruptcy, administrative or other court or governmental
         proceedings pending or threatened (in writing) against the Company, any
         Investment Entity or any Property which might have a material adverse
         effect;

                  (ix) not cause or permit the Company to engage in any
         transaction which would cause any obligation, or action taken or to be
         taken, hereunder to be a non-exempt (under a statutory or
         administrative class exemption) prohibited transaction under the
         Employee Retirement Income Security Act of 1974 (or any successor
         legislation thereto), as amended ("ERISA"). MC further covenants and
         agrees to deliver to SLAB such certifications or other evidence from
         time to time throughout the term of this Agreement, as requested by
         SLAB in its sole discretion, that: (i) the Company is not an "employee
         benefit plan" as defined in Section 3(3) of ERISA, which is subject to
         Title I of ERISA, or a "governmental plan" within the meaning of
         Section 3(3) of ERISA; (ii) the Company is not subject to state
         statutes regulating investments and fiduciary obligations with respect
         to governmental plans; and (iii) one or more of the following
         circumstances is true:

                           (1)      Equity interests in the Company are publicly
                                    offered securities, within the meaning of 29
                                    C.F.R. SECTIONS 2510.3-101(b)(2);

                           (2)      Less than twenty-five percent (25%) of each
                                    outstanding class of equity interests in the
                                    Company are held by "benefit plan investors"
                                    within the meaning of 29 C.F.R. SECTIONS
                                    2510.3-101(f)(2); or

                           (3)      The Company qualifies as an "operating
                                    company" or a "real estate operating
                                    company" within the meaning of 29 C.F.R.
                                    SECTIONS 2510.3- 101(c) or (e) or an
                                    investment company registered under The
                                    Investment Company Act of 1940.

                  (x) cause the Company, the Investment Entities and the
         Properties to comply at all times with all laws, statutes, ordinances,
         regulations and other governmental or quasi-

                                       16
<PAGE>

         governmental requirements to which the Company or any Investment Entity
         is subject and with private covenants now or hereafter relating to the
         ownership, construction, use or operation of the Properties, including,
         but not limited to, those concerning environmental or ecological
         requirements;

                  (xi) keep the Properties free and clear of monetary liens
         (except pursuant to Section 11(d) or with required approval under
         Section 11(b));

                  (xii) cause the Company, the Investment Entities and the
         property manager under the Management Agreement to take such
         commercially reasonable actions as may be necessary or appropriate to
         own and operate the Properties in a professional, diligent and
         first-class manner;

                  (xiii) not commit or suffer any waste of the Properties or
         make or permit to be made any change in the use of the Properties which
         will in any way materially increase the risk of fire or other hazard
         arising out of the operation of the Properties, or take or cause to be
         taken any action that might invalidate or give cause for cancellation
         of any insurance policy, or do or permit to be done thereon anything
         that could in any material way impair the value of the Properties;

                  (xiv) cause the Company, the Investment Entities and the
         property manager under the Management Agreement to keep and maintain
         proper and accurate books, records and accounts (separate from those of
         MC's affiliates or any other person or entity) reflecting all of the
         financial affairs of the Company and the Investment Entities and all
         items of income and expense in connection with the operation of the
         Properties;

                  (xv) cause the property manager under the Management Agreement
         and the asset manager under Asset Management Agreement to comply with
         the terms and conditions of such agreements and not permit a breach
         thereof by such managers;

                  (xvi) cause the Company and the Investment Entities to pay
         promptly all taxes, assessments and other governmental impositions with
         respect to the Company, the Investment Entities and the Properties;

                  (xvii) if the Company or the Investment Entities have
         employees, cause the payment of the salaries and other compensation of
         such employees (or the proportionate share of such salaries and
         compensation allocable to the Company and the Investment Entities, as
         applicable);

                  (xviii) provide prompt notice to SLAB of any material breach
         hereunder by MC;

                                       17
<PAGE>

                  (xix) maintain (with respect to MC) an "investment grade"
         rating by Standard Poor's or Moody's or a book value determined in
         accordance with generally accepted accounting principles (excluding
         good will and adding back all accumulated depreciation and
         amortization) of at least $1,500,000,000;

                  (xx) not cause or permit the Company and the Investment
        Entities to commingle their funds and other assets with those of any
        affiliate of MC or any other person or entity; and

                  (xxi) cause the Company and the Investment Entities to
        maintain their assets in such a manner that it will not be costly or
        difficult to segregate, ascertain or identify their individual assets
        from those of any affiliate of MC or any other person or entity.

               12. DETERMINATION OF PROFITS AND LOSSES. The net profits and net
losses of the Company shall be as determined for federal income tax purposes for
each calendar year. The Members intend that the Company be treated as a
partnership for tax purposes and each Investment Entity be treated as a
disregarded entity for income tax purposes. The Members hereby agree that they
will not cause or permit the Company or any Investment Entity to become a
taxable entity. No Member shall under any circumstances be required to pay or
restore any portion of the negative balance in its capital account or to repay
any portion thereof to the Company, any Company creditor or another Member. No
Member may demand the return of its capital contributions, it being intended
that all distributions be made pursuant to Section 13 below.

               13. ALLOCATION OF INCOME AND LOSSES; DISTRIBUTIONS; GUARANTEED
PAYMENTS.

        (a)    TAX ALLOCATIONS.

               (i) Tax losses of the Company for any fiscal period shall be
        allocated (A) first to MC, until its capital account has been reduced to
        zero, (B) then to SLAB, until its capital account has been reduced to
        zero, and (C) then to the Members in accordance with their Residual
        Percentages.

               (ii) Taxable income of the Company for any fiscal period shall be
        allocated (A) first to SLAB, until SLAB has been allocated an aggregate
        amount of income under this clause (ii) equal to the amount
        distributable to SLAB pursuant to Section 13(b)(2)(i) and (B) thereafter
        to the Members in accordance with their Residual Percentages.

               (iii) For purposes of this Section 13(a)(iii), Guaranteed
        Payments shall not be treated as distributions. On or before April 15 of
        each year, the Company shall, upon the written request of any Member
        ("Requesting Member"), pay (to the extent the Company has available
        funds, determined prior to making distributions for the preceding
        calendar year), as an advance against future distributions to the
        Requesting Member under Section 13(b)(1) and

                                       18
<PAGE>

         13(b)(2)(iv), (a "Tax Payment Advance") to the Requesting Member an
         amount equal to the excess of (A) 40% multiplied by the Requesting
         Member's cumulative allocations of income pursuant to Section
         13(a)(ii)(B), over (B) the sum of (x) the Requesting Member's
         cumulative distributions from the Company under Sections 13(b)(1) and
         13(b)(2)(iv) from the date hereof through the end of the preceding
         calendar year (net of repayments thereof) and (y) the outstanding
         balance(s) of all the unpaid Tax Payment Advances to such Requesting
         Member. A copy of any request for a Tax Payment Advance shall be given
         by the requesting Member to the other Member. Such advance shall not
         bear interest, and shall be repayable both (A) out of future
         distributions to the Requesting Member under Sections 13(b)(1) and
         13(b)(2)(iv) (such payment to be made by withholding such
         distributions, with such distributions being deemed to have been
         distributed to the Requesting Member and then paid by the Requesting
         Member to the Company), and (B) if earlier, upon the liquidation of the
         Company or upon demand following the Requesting Member's ceasing for
         any reason to be a Member hereunder, which payments shall be made from
         the distributions otherwise payable to such Member in connection with
         the liquidation. In no event shall the Company be required to borrow
         money or to sell any asset in order to fund any Tax Payment Advance.

        (b)    DISTRIBUTIONS.

               (1) CASH FLOW FROM OPERATIONS. Distributions of net available
cash from any source (other than distributions of sale, casualty, condemnation,
loan or securitization proceeds described in Section 11(d)) and proceeds of any
other capital transactions remaining after Guaranteed Payments (as defined in
and in accordance with Section 13(c) below), expenses, debt service, reserves
and capital improvements for any period shall be made as follows, after first
repaying any loans made by the Members to the Company and Investment Entities
pursuant to Section 9 (loans which have been outstanding the longest shall be
repaid first, with any loans that have been outstanding for an equal period
being repaid pro rata, in proportion to such loans' respective balances, and
with the accrued and unpaid interest being repaid first and then the principal
being repaid next) (such excess net available cash, the "Excess Cash Flow"): to
the Members, PARI PASSU, 55% to SLAB and 45% to MC; PROVIDED, HOWEVER, that the
Managing Member shall have the right to not make the distribution of such Excess
Cash Flow distributable to SLAB and hold it in Company reserve earmarked to make
the distribution under Section 13(b)(2)(i) (in which case, the amount
distributable to SLAB under Section 13(b)(2)(i) shall be reduced by the amount
so earmarked when distribution thereof is made to SLAB under Section
13(b)(2)(i)) and distribute such Excess Cash Flow to SLAB as a distribution
under Section 13(b)(2)(i) at such time as SLAB would otherwise be entitled to a
distribution under Section 13(b)(2)(i).

               (2) SALE/REFINANCING PROCEEDS. Distributions of sale,
disposition, loan or securitization proceeds described in Section 11(d) (or any
insurance or condemnation proceeds not used to repair, rebuild or replace the
Properties) and proceeds of any other capital transactions remaining after
Guaranteed Payments (as defined in and in accordance with the subsection
entitled

                                       19
<PAGE>

"Guaranteed Payments" below in this Section 13), and reasonable, ordinary and
necessary expenses being paid in connection therewith shall be made in the
following order of priority after first repaying any loans made by the Members
to the Company and Investment Entities (loans which have been outstanding the
longest shall be repaid first, with any loans that have been outstanding for an
equal period being repaid pro rata, in proportion to such loans' respective
balances, and with the accrued and unpaid interest being repaid first and then
the principal being repaid next):

               (i) First, such amounts (including reserved amounts under Section
        13(b)(1)) shall be distributed to SLAB until SLAB has received an amount
        equal to (A) the product of two percent (2%) of SLAB's Capital
        Contributions times (B) the number of years (commencing with January 1,
        2000) during which such Capital Contributions were outstanding (with
        each partial year treated as a full year) reduced by cash flow paid to
        SLAB in the 55/45 ratio under Section 13(b)(1) and not held in reserves
        described in Section 13(b)(1);

               (ii) Second, the balance shall be distributed to SLAB to the
        extent of its Capital Contributions attributable to the Properties as
        set forth on Exhibit C for which a sale, loan or securitization has
        occurred and which have not previously been repaid pursuant to this
        section 13(b)(2)(ii);

               (iii) Third, the balance shall be distributed to MC to the extent
        of its Capital Contributions attributable to the Properties as set forth
        on Exhibit F for which a sale, loan or securitization has occurred which
        have not been repaid by distributions to it under this Section
        13(b)(2)(iii); and

               (iv) Next, the balance shall be distributed to the Members, PARI
        PASSU, 55% to SLAB and 45% to MC.

               (3) LIQUIDATING DISTRIBUTIONS. Upon liquidation of the Company,
after all of the Company's debts have been paid, distributions shall be made in
accordance with the Members' capital accounts.

        (c) GUARANTEED PAYMENTS. The Company shall make guaranteed payments
under Code Section 707(c) ("Guaranteed Payments"), on the fifth (5th) day of
each calendar month (commencing with February 5, 2000) from available cash from
any source, to the Members for the use of their respective capital contributions
as follows (with amounts not paid currently being added to the unpaid principal
amount of the Guaranteed Payments then owing):

               (1) First, to SLAB in an amount equal to SLAB's accrued and
        unpaid Guaranteed Payments, which shall mean an amount equal to SLAB's
        capital contributions which have not been repaid by distributions to it
        under Section 13(b)(2)(ii) multiplied by LIBOR plus 200 basis

                                       20
<PAGE>

         points per annum, compounded monthly (using the rate under Section 9
         applicable that month applied to total outstanding balance), until the
         date the payment is made; and

               (2) After making the Guaranteed Payments described in Section
        13(c)(1), to MC in an amount equal to MC's accrued and unpaid Guaranteed
        Payments, which shall mean an amount equal to MC's capital contributions
        which have not been repaid by distributions to it under Section
        13(b)(2)(iii) multiplied by the rate in effect from time to time that is
        122% of the rate used in Section 13(c)(1).

               14. RESTRICTIONS ON TRANSFER. Neither of the Members shall
transfer, assign, pledge or hypothecate any of their respective right, title or
interest in the Company, or permit transfers of direct or indirect ownership in
such Member without the prior written approval of the other Member, which
approval may be granted or withheld in the other Member's sole and absolute
discretion, except as may be required by law or by reason of an individual's
death, incapacity or divorce, and except as necessary to effect the transactions
described in Section 11(d). Nothing in this Section 14 shall be construed to
prohibit or restrict any sale, transfer, assignment, pledge or hypothecation of
any stock (or any interests therein) of any publicly-traded entity which
directly, indirectly or ultimately owns any interest in any Member, or the
transfer of units or partnership interests in Mack-Cali Realty, L.P, or the
transfer of any direct or indirect interest in the Company by any Member to its
affiliates, or the transfer of any interest in DLJ Mortgage Capital, Inc. No
transfer herein shall affect the obligations and liabilities of the transferring
party hereunder.

               15. WAIVER OF NON-COMPETITION. Each Member hereby acknowledges
and agrees that each Member and its affiliates may continue to pursue their
existing businesses, including without limitation, acquisition, financing,
development, operation, management, leasing of, and investments in, any
properties or projects, and the disposition thereof, regardless of whether the
same is competitive with the Properties. Each Member further acknowledges and
agrees that no Member or any of its affiliates shall be obligated to present any
particular investment or business opportunity to the Company or the other Member
or its affiliates, even if such opportunity is of a character which, if
presented to the Company or the other Member, could be undertaken by the Company
or the other Member, and each Member and each of its affiliates shall have the
right to acquire for its own account, or to recommend to others, any such
opportunity. Notwithstanding any provision to the contrary in this Agreement, MC
hereby agrees not to induce any existing tenant at the Properties (while owned
by the Company or the Investment Entities owned by the Company) to breach,
modify or terminate such tenant's lease at the Properties in favor of a lease at
another property owned by MC or its affiliates

               16. ACCOUNTANTS AND ATTORNEYS; ENGINEERING REPORTS AND
APPRAISALS. PricewaterhouseCoopers shall be the Company's accountants, and the
Company may engage any of Battle Fowler LLP, Weil Gotshal & Manges LLP and Farer
Siegel & Fersko (with respect to environmental matters) as Company's attorneys.
Other accountants may be engaged so long as their engagement is not to perform
an audit of the Company's or any Investment Entity's books or to sign tax

                                       21
<PAGE>

returns for the Company or any Investment Entity (all of which must be done by
PricewaterhouseCoopers). Any change of Company accountants, or additional
attorneys, shall be subject to the reasonable approval of both Members. The
Managing Member shall cause engineering reports and appraisals of the Properties
to be prepared at the Company expense within 30 days after the Outside Closing
Date.

               17. REPRESENTATIONS AND WARRANTIES. Each Member hereby represents
and warrants to the other Member as follows:

               i.      Such Member is duly formed and validly existing under the
                       laws of the jurisdiction of its organization with full
                       power and authority to enter into this Agreement and to
                       conduct its business to the extent contemplated in this
                       Agreement;

               ii.     This Agreement has been duly authorized, executed and
                       delivered by such Member and constitutes the valid and
                       legally binding agreement of such Member, enforceable in
                       accordance with its terms against such Member, except as
                       such enforceability may be limited by bankruptcy,
                       insolvency, moratorium and other similar laws relating to
                       creditors' rights generally, by general equitable
                       principles and by any implied covenant of good faith and
                       fair dealing;

               iii.    The execution and delivery of this Agreement by such
                       Member and the performance of its duties and obligations
                       hereunder do not result in a breach of any of the terms,
                       conditions or provisions of, or constitute a default
                       under, any indenture, mortgage, deed of trust, credit
                       agreement, note or other evidence of indebtedness, or any
                       lease or other agreement, or any license, permit,
                       franchise or certificate to which such Member is a party
                       or by which it is bound or to which its properties are
                       subject or require any authorization or approval under or
                       pursuant to any of the foregoing, or violate any statute,
                       regulation, law, order, writ, injunction, judgment or
                       decree to which such Member is subject, or require any
                       governmental consent; and

               iv.     Such Member is relying on such Member's own tax, legal
                       and accounting professionals and consultants in
                       connection with such Member entering into this Agreement.

               18. WAIVER OF RIGHT OF PARTITION. Each Member hereby waives all
rights to commence an action for the partition of the Company, the Investment
Entities or the Company's or the Investment Entities' property.

                                       22
<PAGE>

               19. MEETINGS. Meetings of the Members shall not be required
unless requested by any Member by written notice to the Company and the other
Member. All Members shall be given written notice of any meeting of the Company
at least twenty (20) days prior to any such meeting by the Member requesting
such meeting. Any meetings shall be held at the record-keeping office of the
Company or at any other reasonably convenient location within New York City or
New Jersey as the requesting Member may reasonably approve and specify in such
notice.

               20. COUNTERPARTS. This Agreement may be executed in counterparts
and execution and delivery by facsimile transmission is authorized for all
purposes.

               21. NOTICES. Any notices or solicitations of approval required or
permitted to be given under the terms of this Agreement shall be in writing and
shall be deemed to have been given when (i) personally delivered with signed
receipt obtained, (ii) when transmitted by facsimile machine, with printed
confirmation of successful transmission to the facsimile machine number set
forth in the appropriate address listed below being obtained by the sender from
the sender's facsimile machine or telephonically from the addressee, or (iii)
when deposited in the United States first class mail if sent postage prepaid by
registered or certified mail, return receipt requested, in each case addressed
as follows:

        IF TO MC:

               c/o Mack-Cali Realty Corporation
               11 Commerce Drive
               Cranford, New Jersey 07016
               with separate notices to the attention of:
               Mr. Mitchell E. Hersh
               Tel:    (908) 272-8000
               Fax:    (908) 272-6755
               and
               Roger W. Thomas, Esq.
               Tel:    (908) 272-2612
               Fax:    (908) 497-0485

        with a copy to:

               Battle Fowler LLP
               75 East 55th Street
               New York, New York  10022
               Attn:   Richard L. O'Toole, Esq.
                       Leslie H. Loffman, Esq.
               Tel:    (212) 856-7000

                                       23
<PAGE>

               Fax:    (212) 856-7810

        and to:

               Battle Fowler LLP
               2049 Century Park East, Suite 2350
               Los Angeles, California 90067
               Attn:   Sanford C. Presant, Esq.
                       Sung H. Shin, Esq.
               Tel:    (310) 788-3000
               Fax:    (310) 277-0336

        IF TO SLAB:

               SLAB Investments Holding, Inc.
               c/o Donaldson, Lufkin & Jenrette
               277 Park Avenue
               New York, New York 10172
               with separate notices to the attention of:
               Mr. John Bricker
               Tel:    (212) 892-2657
               Fax:    (212) 892-6101
               and
               Mr. Dante LaRocca
               Tel:    (212) 892-4964
               Fax:    (212) 892-6101

               and
               280 Park Avenue, 5th Floor
               New York, New York 10172
               Attn:   Mr. Mark Competiello
               Tel:    (212) 892-4939
               Fax:    (212) 892-4955

                                       24
<PAGE>

        with a copy to:

               Weil Gotshal & Manges
               767 Fifth Avenue
               New York, New York  10153
               Attn:   J. Philip Rosen, Esq.
                       Larry Gelbfish, Esq.
               Tel:    (212) 310-8000
               Fax:    (212) 310-8007

The time to respond to any notice shall commence to run on the date of delivery
at the appropriate addresses (or attempted delivery if delivery is refused
during normal business hours).

               22. ATTORNEYS' FEES. In the event a party hereto files any
action, lawsuit or other legal proceeding against another party hereto by reason
of any breach of any of the covenants, agreements or provisions contained in
this Agreement, the prevailing party in such proceeding will be entitled to have
and recover certain fees from the other party including all reasonable
attorneys' fees and costs resulting therefrom.

               23. SET-OFF. In addition to any rights and remedies of the
Members provided by law, each Member shall have the right, without prior notice
to the Company (with such notice being expressly waived by the Company to the
extent permitted by law) upon any Bankruptcy Action with respect to the Company
or any Investment Entity, to set-off and apply against any amounts owed to such
Member, any amounts owing from such Member to the Company, at or at any time
after the occurrence of such Bankruptcy Action, and the aforesaid right of
set-off may be exercised by such Member against the Company or against any
trustee in bankruptcy, debtor in possession, assignee for the benefit of
creditors, receiver or execution, judgment or attachment creditor, or anyone
else claiming through or against the Company, notwithstanding that such right of
set-off shall not have been exercised by such Member prior to the making,
filing, issuance or service upon such Member of, or of notice of, any such
Bankruptcy Action.

               24. CONSTRUCTION. Headings at the beginning of each section or
subsection are solely for the convenience of the parties and are not a part of
this Agreement. This Agreement shall not be construed as if it had been prepared
by one of the parties, but rather as if both parties had prepared the same. All
exhibits, schedules and other attachments hereto are incorporated as a part of
this Agreement by this reference. This Agreement shall be interpreted using New
Jersey law (without regard to conflict of law provisions). As used herein, the
words "lease," "tenant" and any derivatives thereof shall also include subleases
and subtenants, as the context permits or requires.

               25. SEVERABILITY. If any term or other provision of this
Agreement is invalid, illegal, or incapable of being enforced by any rule of law
or public policy, all of the other conditions and

                                       25
<PAGE>

provisions of this Agreement will nevertheless remain in full force and effect,
so as to cause the economic substance of the transactions contemplated hereby
not to be affected in any adverse manner to either party.

               26. SOLE DISCRETION. In any instance in this Agreement in which a
Member (including the Managing Member) may act in its sole discretion, such sole
discretion means the sole, absolute and unfettered discretion of such Member,
without any express or implied obligation or duty of good faith.

               27. PRESS RELEASES. Before either Member discloses in writing to
any third party any of the terms and conditions of this Agreement (or the
transaction contemplated hereby), such Member shall provide a copy of such
writing to the other Member for its review and comment (but not its approval).
Either Member may request a meeting to discuss any such writing.

                               [signatures follow]

                                       26
<PAGE>

               IN WITNESS WHEREOF, the undersigned Members have executed this
Agreement as of the date first written above.

                         SLAB INVESTMENTS HOLDING, INC.,
                         a Delaware corporation

                         By:
                              ------------------------------------
                                John Bricker, its Vice President

                         MACK-CALI REALTY, L.P.,
                         a Delaware limited partnership

                         By:    Mack-Cali Realty Corporation,
                                a Maryland corporation,
                                its general partner

                                By:
                                    ------------------------------
                                      Roger W. Thomas,
                                      its Executive Vice President

                               [END OF SIGNATURES]

                                       27
<PAGE>

                                    EXHIBIT A
                                    ---------

                   CAPITAL CONTRIBUTIONS; FUNDING PROPORTIONS;
                            AND RESIDUAL PERCENTAGES

<TABLE>
<CAPTION>
                       CAPITAL               FUNDING                RESIDUAL
MEMBER                 CONTRIBUTIONS         PROPORTIONS            PERCENTAGES

<S>                    <C>                       <C>                   <C>
MC                     $  68,400,000             45%                   45%
SLAB                   $  83,600,000             55%                   55%

                       -------------             ----                 ----
Total:                 $ 152,000,000             100%                 100%
</TABLE>

                                       A-1

<PAGE>

                                    EXHIBIT B
                                    ---------

                                LEGAL DESCRIPTION

                                 [see attached]

                                       B-1

<PAGE>

                                    EXHIBIT C
                                    ---------

                    SLAB ALLOCATION OF CAPITAL CONTRIBUTIONS

                                 [see attached]

                                       C-1

<PAGE>

                                    EXHIBIT D

                             REPORTING REQUIREMENTS

        1. GOVERNMENTAL REPORTS; MEETINGS. MC shall, at Company expense, use
reasonable efforts to cause to be prepared and timely filed with appropriate
federal, state and foreign regulatory and administrative bodies, all reports
required to be filed with such entities under then current applicable laws,
rules and regulations, subject to the reasonable approval of the Members. Such
reports shall be prepared on the accounting or reporting basis required by such
regulatory bodies. Each Member shall be provided with a copy of any such report.

        2. ACCESS; AUDIT. Each Member shall permit any other Member to review
and copy, during normal business hours at the office of the Company, all Company
financial records and information. Each Member shall have the right to have such
records and information audited at Company expense; PROVIDED, HOWEVER, if such
audit reveals material errors or omissions in such records and information due
to actual fraud or misappropriation of funds by any Member, such Member shall
reimburse the Company for the expense of audit. MC shall maintain (at the office
of the Company) reports required or otherwise prepared and delivered hereunder,
copies of which shall be furnished to each Member when available, at the
Company's expense, together with (upon request from any Member) such
supplementary records and reports as are necessary to reflect the allocation
among the Members of the tax items and distributions of the Company shown on any
reports furnished (or required to be furnished) to the Members under this
Agreement. MC shall promptly provide any and all records, reports and
information regarding the Company, any Investment Entity or any Property
requested by SLAB from time to time to the extent such records, reports and
information are in MC's possession or control.

         3. FINANCIAL AND STATUS REPORTS. (a) MC shall cause the following
reports to be issued at Company expense:

               (i) MC shall use reasonable efforts to cause to be issued to the
        Members, at Company expense, audited annual financial reports (except
        for year 1999, which may be unaudited but certified by MC) within 90
        days following the close of each year (including a balance sheet and
        income and expense statements, showing sources and uses of funds, cash
        on hand, distributions, changes in financial position, tax information,
        unpaid Guaranteed Payments, fees under the Asset Management Agreement
        and the Management Agreement, Capital Contributions, and unrepaid Member
        loans on a Member-by-Member basis). Such financial reports shall be
        prepared using GAAP; and

               (ii) MC shall use reasonable efforts to cause to be issued to the
        Members quarterly unaudited financial reports, in reasonable detail and
        certified by the Managing Member, within 40 days after the close of each
        calendar quarter other than the fourth quarter of each year

                                      D-1
<PAGE>

         (commencing with the calendar quarter ending on March 31, 2000),
         internally prepared by MC and reviewed by the Company's accountants,
         including a balance sheet and income and expense statements (showing
         receipts on a tenant-by-tenant basis, and material defaults, to the
         extent requested by either MC or SLAB upon reasonable notice), sources
         and uses of funds, cash on hand, distributions, changes in financial
         position, unpaid Guaranteed Payments, Asset Management Fees, Capital
         Contributions, and unrepaid Member loans.

        (b) In preparing reports required under this Agreement, MC may rely on
information furnished by third parties (including property managers and
accountants) to the extent that it is reasonable to do so.

                                       D-2

<PAGE>

                                    EXHIBIT E
                                    ---------

                                 CURRENT BUDGETS

                   [MACK-CALI TO PROVIDE TO DLJ FOR APPROVAL]

                                       E-1

<PAGE>

                                    EXHIBIT F
                                    ---------

                     MC ALLOCATION OF CAPITAL CONTRIBUTIONS

                                 [see attached]

                                       F-1

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