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                                                                   EXHIBIT 10.61




                      DEED OF TRUST AND SECURITY AGREEMENT
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                      DEED OF TRUST AND SECURITY AGREEMENT

                                TABLE OF CONTENTS

<TABLE>
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         1.       Payment of Indebtedness ................................................................        7

         2.       Covenants of Title .....................................................................        7

         3.       Usury ..................................................................................        8

         4.       Impositions ............................................................................        8

         5.       Escrow Deposits ........................................................................        9

         6.       Change in Taxes ........................................................................       12

         7.       Insurance ..............................................................................       13

         8.       Insurance/Condemnation Proceeds ........................................................       14

         9.       Restoration Following Fire and Other Casualty or Condemnation ..........................       16

         10.      Disposition of Condemnation or Insurance Proceeds ......................................       22

         11.      Fire and Other Casualty; Self-Help .....................................................       24

         12.      Rent Insurance Proceeds ................................................................       25

         13.      Intentionally omitted ..................................................................       25

         14.      Repair; Alterations; Waste; Environmental ..............................................       25

         15.      Intentionally Omitted ..................................................................       30

         16.      Independence of Security ...............................................................       30

         17.      No Other Liens; Secondary Financing ....................................................       31

         18.      Management .............................................................................       35

         19.      Intentionally omitted ..................................................................       36

         20.      Sidewalks, Municipal Charges ...........................................................       36

         21.      Ground Lease ...........................................................................       36

         22.      Future Leases ..........................................................................       44

         23.      Intentionally Omitted ..................................................................       47

         24.      Leases; Foreclosure ....................................................................       47

         25.      One-Time Transfer of Ownership .........................................................       47
</TABLE>




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<TABLE>
<S>                                                                                                              <C>
         26.      Events of Default ......................................................................       52

         27.      Remedies Upon Default ..................................................................       54

         28.      Acceleration Interest ..................................................................       58

         29.      Late Charge ............................................................................       59

         30.      Waiver of Statutory Rights .............................................................       59

         31.      Security Interest ......................................................................       60

         32.      Right of Entry .........................................................................       61

         33.      Estoppel Certificate ...................................................................       61

         34.      Annual Statements ......................................................................       61

         35.      Rights Cumulative ......................................................................       63

         36.      Subrogation ............................................................................       63

         37.      No Waiver ..............................................................................       63

         38.      Deed of Trust Extension ................................................................       63

         39.      Indemnification ........................................................................       64

         40.      Nonrecourse ............................................................................       64

         41.      Attorneys' Fees ........................................................................       67

         42.      Administrative Fees ....................................................................       67

         43.      Trustee's Costs and Expenses; Governmental Charges .....................................       68

         44.      Protection of Security; Costs and Expenses .............................................       68

         45.      Notices ................................................................................       70

         46.      Release ................................................................................       71

         47.      Applicable Law .........................................................................       71

         48.      Intentionally Omitted ..................................................................       71

         49.      Invalidity .............................................................................       72

         50.      Captions ...............................................................................       72

         51.      Modifications ..........................................................................       72

         52.      Bind and Inure .........................................................................       72

         53.      Replacement of Notes ...................................................................       72

         54.      Time of the Essence ....................................................................       73
</TABLE>




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<TABLE>
<S>                                                                                                              <C>
         55.      Approvals and Consents .................................................................       73

EXHIBIT A - LEGAL DESCRIPTION ............................................................................       78

Exhibit B - Form of Subordination, Nondisturbance and Attornment Agreement ...............................       82
</TABLE>




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<PAGE>   5
                      DEED OF TRUST AND SECURITY AGREEMENT


         THIS DEED OF TRUST is made as of July 23, 1996, by 1700 LINCOLN
LIMITED, a Colorado limited partnership whose general partners are ARICO-Denver,
Inc., and 1700 Lincoln, Inc., having its principal place of business at 126 East
56th Street, New York, New York, 10022 (herein referred to as "Grantor") to the
Public Trustee of the City and County of Denver, Colorado (herein referred to as
"Trustee") for the benefit of CONNECTICUT GENERAL LIFE INSURANCE COMPANY a
Connecticut corporation having its principal place of business at 900 Cottage
Grove Road, Bloomfield, Connecticut 06002 ("CGLIC"), AMERICAN GENERAL LIFE
INSURANCE COMPANY, a Texas corporation having its principal place of business at
2929 Allen Parkway, Houston, Texas 77019 ("AG") and MASSACHUSETTS MUTUAL LIFE
INSURANCE COMPANY, a Massachusetts corporation, having its principal place of
business at 1295 State Street, Springfield, Massachusetts 01111 ("Mass Mutual")
(CGLIC, AG and Mass Mutual are hereinafter referred to collectively as
"Beneficiary").

                                   WITNESSETH:

         THAT, to secure (i) payment to Beneficiary of the aggregate principal
indebtedness of Ninety-Eight Million Dollars ($98,000,000) together with
interest thereon, as evidenced by (a) that certain promissory note in the
original principal amount of Thirty-two Million Six Hundred Sixty-Six Thousand,
Six Hundred Sixty-Six and No/100 Dollars ($32,666,666) (hereinafter referred to
as the "CGLIC Note") of even date herewith, and any renewals, extensions or
modifications thereof, given by Grantor to CGLIC and made payable to the order
of CGLIC, with the final payment being due and payable on August 1, 2001, in and
by which CGLIC Note the Grantor promises to pay the said principal indebtedness
and interest at the rate and in installments as provided in the CGLIC Note, (b)
that certain promissory note in the original principal amount of Thirty-two
Million Six Hundred Sixty-Seven Thousand, Six Hundred Sixty-Seven and No/100
Dollars ($32,666,667) (hereinafter referred to as the "AG Note") of even date
herewith, and any renewals, extensions or modifications thereof, given by
Grantor to AG and made payable to the order of AG, with the final payment being
due and payable on August 1, 2001, in and by which AG Note the Grantor promises
to pay the said principal indebtedness and interest at the rate and in
installments as provided in the AG Note, and (c) that certain promissory note in
the original principal amount of Thirty-two Million Six Hundred Sixty-Seven
Thousand, Six Hundred Sixty-Seven and No/100 Dollars ($32,666,667) (hereinafter
referred to as the "Mass Mutual Note") of even date herewith, and any renewals,
extensions or modifications thereof,
<PAGE>   6
given by Grantor to Mass Mutual and made payable to the order of Mass Mutual,
with the final payment being due and payable on August 1, 2001, in and by which
Mass Mutual Note the Grantor promises to pay the said principal indebtedness and
interest at the rate and in installments as provided in the Mass Mutual Note,
(the CGLIC Note, the AG Note and the Mass Mutual Note are sometimes hereinafter
referred to collectively as the "Notes" and individually as a "Note") (ii) the
performance of the covenants herein contained and the payment of any monies
expended by the Beneficiary in accordance with its rights hereunder, (iii) the
payment of all obligations and the performance of all covenants of Grantor under
any other loan documents, agreements or instruments between Grantor and
Beneficiary given in connection with or related to this Deed of Trust or the
Notes, and (iv) any and all additional advances made by Beneficiary to protect
or preserve the Security or the security interest created hereby on the
Security, or for taxes, assessments, or insurance premiums as hereinafter
provided or for performance of any of Grantor's obligations hereunder or for any
other purpose provided herein (whether or not the original Grantor remains the
owner of the Security at the time of such advances) (all of the aforesaid
indebtedness and obligations of Grantor being herein called the "Indebtedness",
and all of the documents, agreements and instruments between Grantor and
Beneficiary now or hereafter evidencing or securing the repayment of, or
otherwise pertaining to, the Indebtedness being herein collectively called the
"Loan Documents"), the Grantor does hereby mortgage, grant, bargain, sell,
assign, pledge, transfer, and convey unto Trustee and to Trustee's successors
and assigns, in trust, with power of sale and right of entry and possession, all
of the following described land, improvements, real and personal property and
rents and leases and all of Grantor's estate, right, title and interest therein
(hereinafter collectively called the "Security"):

         The land described in Exhibit A attached hereto and made a part hereof
situate, lying and being in the City and County of Denver, and State of Colorado
(the "Land");

         TOGETHER with all buildings and other improvements now or hereafter
located on said Land or any part thereof, including but not limited to, all
extensions, betterments, renewals, renovations, substitutes and replacements of,
and all additions and appurtenances to the Security (the "Improvements");




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         TOGETHER with all of the right, title and interest of Grantor in and to
the land lying in the bed of any street, road, highway or avenue in front of or
adjoining the Land to the center lines thereof;

         TOGETHER with all of Grantor's right, title, and interest in, to, and
under that certain Lease dated February 5, 1981 (recorded February 9, 1981 in
Book 2322 at Page 182) between Lincoln Building Corporation and Grantor, as
amended (the "Ground Lease"), the entire interest in the Ground Lease, both as
to the lessor and the lessee thereunder, being held by Grantor;

         TOGETHER with the right to use in connection with the operation of the
Security the name "One Norwest Center" and any other name similar thereto to the
extent that Grantor has the right to assign and pledge such right hereunder;




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<PAGE>   8
         TOGETHER with all easements now or hereafter located on or appurtenant
to the Land and/or the Improvements or under or above the same or any part
thereof, rights-of-way, licenses, permits, approvals and privileges, belonging
or in any way appertaining to the Land and/or Improvements including without
limitation (i) any drainage ponds or other like drainage areas not located on
the Land which may be required for water run-off, (ii) any easements necessary
to obtain access from the Land to such drainage areas, or to any other location
to which Grantor has a right to drain water or sewage (iii) any land required to
be maintained as undeveloped land by the zoning rules and regulations applicable
to the Land, and (iv) any easements and agreements which are or may be
established to allow satisfactory ingress to, egress from and operation of the
Land and/or the Improvements;

         TOGETHER with any and all awards heretofore made and hereafter to be
made by any governmental, municipal or State authorities to the present and all
subsequent owners of the Security for the taking of all or any portion of the
Security by power of eminent domain, including, without limitation, awards for
damage to the remainder of the Security and any awards for any change or changes
of grade of streets affecting the Security, which said awards are hereby
assigned to Beneficiary, and Beneficiary, at its option, is hereby authorized,
directed and empowered, subject to the terms of this Deed of Trust, to collect
and receive the proceeds of any such awards from the authorities making the same
and to give proper receipts and acquittances therefor, and to apply the same
toward the payment of the Indebtedness, notwithstanding the fact that such
amount may not then be due and payable; and Grantor hereby covenants and agrees
to and with Beneficiary, upon request by Beneficiary, subject to the terms of
this Deed of Trust, to make, execute and deliver, at Grantor's expense, any and
all assignments and other instruments sufficient for the purpose of assigning
the aforesaid awards to Beneficiary, free, clear and discharged of any and all
encumbrances of any kind or nature whatsoever (all of the foregoing Land,
Improvements, rights, easements,




                                       -4-
<PAGE>   9
leasehold interests, rights-of-way, licenses, privileges, and awards,
collectively, the "Real Property");

         TOGETHER with all proceeds, insurance or otherwise, paid for the damage
done to any of the Security and all proceeds of the conversion, voluntarily or
involuntarily, of any of the Security into cash or liquidated claims;

         TOGETHER with all fixtures, machinery, equipment, goods, and every
other article of personal property, tangible or intangible, now or hereafter
attached to or used in connection with the Real Property, or placed on any part
thereof and whether or not attached thereto, appertaining or adapted to the use,
management, operation or improvement of the Real Property, insofar as the same
and any reversionary right thereto may now or hereafter be owned or acquired by
Grantor, including, but without limitation: all partitions; screens; awnings;
shades; blinds; floor coverings; hall and lobby equipment; heating, lighting,
plumbing, ventilating, refrigerating, incinerating, elevator, escalator, air
conditioning and communication plants or systems with appurtenant fixtures;
vacuum cleaning systems; call systems; sprinkler systems and other fire
prevention and extinguishing apparatus and materials; all equipment, manual,
mechanical and motorized, for the construction, maintenance, repair and cleaning
of, and removal of snow from, parking areas, walks, underground ways, truck
ways, driveways, common areas, roadways, highways and streets; all equipment,
manual, mechanical and motorized, for the transportation of customers or
employees to and from the store facilities on the Real Property; all telephone,
computers and other electronic equipment and appurtenances thereto, including
software; and all other machinery, pipes, poles, appliances, equipment, wiring,
fittings, panels and fixtures; and any proceeds therefrom, any replacements
thereof or additions or accessions thereto; and all building materials, supplies
and other property delivered to the Real Property for incorporation into the
Improvements thereon, all of which are declared to be a part of the realty and
covered by the lien hereof,




                                       -5-
<PAGE>   10
but said lien shall not cover any fixture, machinery, equipment or article of
personal property which is owned by a tenant or third party manager;

         TOGETHER with all of Grantor's books of accounts and records relating
to the Security, including all computers and software relating thereto.

         TOGETHER with all contracts for sale and leases in the nature of sales
of the Real Property, or any portion thereof, now and hereafter entered into and
all right, title and interest of Grantor thereunder, including, without
limitation, cash or securities deposited thereunder to secure performance by the
lessees or contract purchasers; all proceeds and revenue arising from or out of
the Real Property or any part thereof; all licenses, permits, franchises,
governmental approvals and all sanitary sewer, drainage, water and utility
service agreements benefiting the Real Property or any part thereof, together
with all accounts, general intangibles, documents, instruments and chattel paper
arising from or in connection with the Real Property, including all books and
records in connection therewith; and all rights of Grantor under any leases,
covenants, agreements, easements, restrictions or declarations recorded with
respect to, or as an appurtenance to, the Real Property or any part thereof (all
of the tangible and intangible personal property described in this and the
previous two paragraphs, collectively, the "Personal Property"), and Grantor's
interest, as lessee, under any lease of property included within the description
of Personal Property above;

         TOGETHER with all of the right, title and interest of Grantor in and to
all and singular the tenements, hereditaments and appurtenances thereunto
belonging to or in any way pertaining to the Security; all the estate, right,
title and claim whatsoever of Grantor, either in law or in equity, in and to the
Security; and any and all other, further or additional title, estate, interest
or right which may at any time be acquired by Grantor in or to the Security, and
if Grantor shall at any time acquire any further estate or




                                       -6-
<PAGE>   11
interest in or to Security, the lien of this Deed of Trust shall attach, extend
to, cover and be a lien upon such further estate or interest automatically
without further instrument or instruments, and Grantor, upon request of
Beneficiary, shall execute such instrument or instruments as shall reasonably be
requested by Beneficiary to confirm such lien, and Grantor hereby irrevocably
appoints Beneficiary as Grantor's attorney-in-fact (which appointment is coupled
with an interest) to execute all such instruments if Grantor shall fail to do so
within ten (10) days after demand;

         TO HAVE AND TO HOLD the Security, and each and every part thereof, unto
the Trustee and its successors and assigns in trust, for the purposes and uses
herein set forth.

         AND, Grantor hereby further covenants, agrees and warrants as follows:

         1. Payment of Indebtedness. Grantor will pay the principal indebtedness
and interest thereon in accordance with the provisions of the Notes and all
prepayment charges, late charges and fees required thereunder, and all
extensions, renewals, modifications, amendments and replacements thereof, and
will keep and perform all the covenants, promises and agreements and pay all
sums provided in, (i) each of the Notes or any other promissory note or notes at
any time hereafter issued to evidence the Indebtedness, (ii) this Deed of Trust
and (iii) any and all other Loan Documents, all in the manner herein or therein
set forth. Subject to Section 40 hereof, each of the persons and/or entities
constituting Grantor hereunder shall be fully liable for such payment and
performance, and such liability shall be joint and several.

         2. Covenants of Title. Grantor has good and indefeasible title to the
entire Real Property in fee simple, has absolute unencumbered title to the
Personal Property, and has good right and full power to sell, mortgage and




                                       -7-
<PAGE>   12
convey the same; the Security is free and clear of easements, restrictions,
liens, leases and encumbrances, except those easements, restrictions, liens,
leases and encumbrances listed on Schedule B of the policy or policies of title
insurance delivered to Beneficiary as of the recordation of this Deed of Trust
(the "Permitted Encumbrances"), to which this Deed of Trust is expressly
subject, or which may hereafter be created in accordance with the terms hereof;
and Grantor will warrant and defend title to the Security against all claims and
demands whatsoever except the Permitted Encumbrances. Beneficiary shall have the
right, at its option and at such time or times as it, in its sole discretion,
shall deem necessary, to take whatever action it may deem necessary to defend or
uphold the lien of this Deed of Trust or otherwise enforce any of the rights of
Beneficiary hereunder or any obligation secured hereby, including without
limitation, the right to institute appropriate legal proceedings for such
purposes.

         3. Usury. In no event shall Grantor be bound to pay interest of more
than the current legal limit for the use, forbearance or detention of the money
loaned pursuant to the Loan Documents, the right to demand any such excess being
hereby expressly waived by Beneficiary.

         4. Impositions. Subject to the provisions of Section 5 hereof, Grantor
will pay, not later than fifteen (15) days before the last day on which the same
may be paid without penalty or interest, all real estate taxes, sewer rents,
water charges and all other municipal and governmental assessments, rates,
charges, impositions and liens (hereinafter referred to as "Impositions") which
now or hereafter are imposed by law upon the Security, whether relating directly
to the Security or to property adjoining or abutting the Security. If any
Imposition is not paid within the time hereinabove specified, Beneficiary shall
have the right to pay the same, together with any penalty and interest thereon,
and the amount or amounts so paid or advanced shall forthwith be payable by
Grantor to Beneficiary and shall be secured by




                                       -8-
<PAGE>   13
the lien of this Deed of Trust. Grantor may in good faith contest, at Grantor's
own cost and expense, by proper legal proceedings, the validity or amount of any
Imposition, on the condition that Grantor first shall deposit with Beneficiary,
as security for the payment of such contested item, an amount equal to the
contested item plus all penalties and interest which would be payable if Grantor
is ultimately required to pay such contested item, and on the further condition
that no amount so contested may remain unpaid for such length of time as shall
permit the Security, or the lien thereon created by the item being contested, to
be sold for the nonpayment thereof, or as shall permit an action, either of
foreclosure or otherwise, to be commenced by the holder of any such lien.
Grantor will not claim any credit on, or make any deduction from the
Indebtedness by reason of the payment of any Imposition.

         Grantor hereby assigns to Beneficiary all rights of Grantor now or
hereafter arising in and to the refund of any Imposition and any interest
thereon. If upon receipt of any such refund by Beneficiary, there exists no
Event of Default (as hereinafter defined) hereunder, then Beneficiary shall pay
over the same to Grantor promptly after such receipt; if there then exists an
Event of Default hereunder, Beneficiary may apply said refund in reduction of
the Indebtedness in whatever order Beneficiary may elect.

         5. Escrow Deposits. Grantor shall deposit with Beneficiary or with an
escrow agent selected by Grantor and approved by Beneficiary, on the first day
of the calendar month immediately following the date of this Deed of Trust and
on the first day of each calendar month thereafter (each of which dates is
hereinafter called the "monthly escrow deposit date") until the payment in full
of the Indebtedness, an amount equal to one-twelfth of the sum of: (a) the
Impositions to be levied, charged, assessed or imposed upon or for the Security
within one year after said monthly tax deposit date, and (b) the total annual
insurance premiums for all insurance required to be maintained by




                                       -9-
<PAGE>   14
Grantor under this Deed of Trust ("Insurance Premiums"). If on any monthly
escrow deposit date the amount of Impositions or Insurance Premiums to be
levied, charged, assessed or imposed within the ensuing one year period shall
not be fixed, such amount for the purpose of computing the deposit to be made by
Grantor hereunder, shall be estimated by Beneficiary, with appropriate
adjustment when the amount of such Impositions and Insurance Premiums is fixed.

         The sums deposited by Grantor under this Section shall be held in an
interest bearing account with interest being retained by Beneficiary and free of
trust except to the extent, if any, that applicable law shall otherwise require
and applied in payment of such Impositions and Insurance Premiums when due.
Grantor shall give thirty (30) days prior written notice to Beneficiary in each
instance when an Imposition or Insurance Premium is due, specifying the
Imposition or Insurance Premium to be paid and the amount thereof, the place of
payment and the last day on which the same may be paid in order to be within the
time limit specified in Section 4 hereof entitled "Impositions" or the last day
before which an Insurance Premium becomes delinquent "Due Date".

         Notwithstanding the foregoing provision and so long as Grantor holds
title to and controls the Security, Impositions and Insurance Premiums are paid
in full when due and there exists no uncured default for which notice is not
required nor any other uncured defaults with respect to which notice has
previously been given, the interest earned by such escrows, less reasonable
escrow costs, will be paid to Grantor on a quarterly basis.

         If for any reason the sums on deposit with Beneficiary or escrow agent
under this Section shall not be sufficient to pay an Imposition or Insurance
Premium within the Due Date, then Grantor shall, within ten (10) days after
demand by Beneficiary, deposit a sum which, when added to all subsequent
deposits, to be made by Grantor hereunder prior to the Due Date will enable




                                      -10-
<PAGE>   15
Beneficiary to pay such Imposition or Insurance Premium in full, together with
any penalty and interest thereon. Beneficiary may change its estimate of
Impositions and Insurance Premiums for any period, on the basis of a change in
an assessment or tax rate or equalization factor or on the basis of a prior
miscalculation or for any other reasonable cause, in which event Grantor shall
deposit with Beneficiary or escrow agent within ten (10) days after demand the
amount of any excess of the deposits which would theretofore have been payable
under the revised estimate over the sums actually deposited.

         If any Imposition shall be levied, charged, assessed or imposed upon or
for the Security, or any portion thereof, and if such Imposition shall also be a
levy, charge, assessment or imposition upon or for any other premises not
covered by the lien of this Deed of Trust, then the computation of the amounts
to be deposited under this Section shall be based upon the entire amount of such
Imposition and Grantor shall not have the right to apportion any deposit with
respect to such Imposition.

         Upon an assignment of this Deed of Trust, the Beneficiary shall have
the right to arrange to transfer all amounts deposited and still in its
possession to the assignee and Beneficiary shall thereupon be completely
released from all liability with respect to such deposit and the Grantor or
owner of the Security shall look solely to the assignee or transferee in
reference thereto.

         Upon the payment in full by Grantor of the entire Indebtedness, any
sums then held by Beneficiary under this Section shall be refunded to Grantor.

         All amounts deposited shall be held by Beneficiary as additional
security for the sums secured by this Deed of Trust, and Grantor hereby grants
to Beneficiary a security interest in such sums, and upon the occurrence of an
Event of Default hereunder Beneficiary may, in its sole and absolute discretion,
apply said amounts to the payment of the Indebtedness in whatever




                                      -11-
<PAGE>   16
order Beneficiary may elect.

         Immediately upon receipt of such by Grantor, Grantor shall deliver to
Beneficiary copies of all notices, demands, claims, bills, and receipts in
relation to the Impositions and Insurance Premiums.

         Notwithstanding the foregoing provisions, Beneficiary will waive the
requirement for deposits as to that portion of Impositions payable directly to
the governmental or other authority by tenants under the terms of leases
approved by Beneficiary, provided satisfactory proof of payment is promptly
furnished to Beneficiary.

         6. Change in Taxes. In the event any tax shall be due or become due and
payable to the United States of America, the State or any political subdivision
thereof with respect to the execution and delivery or recordation of this Deed
of Trust or any other Loan Document or the interest of the Beneficiary in the
Security, Grantor shall pay such tax at the time and in the manner required by
applicable law and Grantor shall hold Beneficiary harmless and shall indemnify
Beneficiary against any liability of any nature whatsoever as a result of the
imposition of any such tax. In the event of the enactment, after the date of
this instrument, of any law changing in any way the present law as to the
taxation of notes or debts secured by mortgages, for, Federal, State, or local
purposes, or the manner of collection of any Impositions, so as to affect this
Deed of Trust or the Notes secured hereby, then Grantor shall upon demand make
such payments to Beneficiary and take such other steps, as may be necessary in
Beneficiary's reasonable judgment, to place Beneficiary in the same financial
position as it was prior to any such enactment, failing which, or if Grantor is
not permitted by law to make such payments, the Indebtedness shall, at the
option of Beneficiary, immediately become due and payable.




                                      -12-
<PAGE>   17
         7. Insurance. Grantor shall at all times until the Indebtedness shall
be paid in full, keep the Security insured against loss or damage for its full
replacement cost (which cost may be reset from time to time at Beneficiary's
reasonable election, but not more frequently than once per year) under policies
of All Risk Replacement Cost Insurance with Agreed Amount Endorsement (including
risks of war and nuclear explosion, if available), and shall further provide
flood insurance (if the Security is situated in an area which is considered a
flood risk area by the federal government or any agency thereof), boiler and
machinery insurance, rent loss insurance in an amount sufficient to cover the
total of all rents accruing from the Security for a one year period,
comprehensive general liability insurance in a minimum amount of $1,000,000, and
excess or umbrella liability of at least $25,000,000, and during any period of
restoration, a policy or policies of builder's "all risk" insurance in an amount
not less than the full insurable value of the Security against such risks as
Beneficiary may reasonably request and such other appropriate insurance as
Beneficiary may reasonably require from time to time for hazards commonly
insured against by owners of properties similar to the Security, in such amounts
and with such companies as shall be approved by Beneficiary with a Best's rating
of A:XII or better, and will assign and deliver the original or a certified copy
of the policy or policies of such insurance to Beneficiary (or in the case of a
blanket policy, an Acord 27). Each such policy shall name Beneficiary as an
additional insured and each policy other than Grantor's commercial general
liability policy shall provide that all proceeds with respect to the Security
shall be payable to Beneficiary, that the same may not be cancelled or modified
except upon thirty (30) days prior written notice to Beneficiary, that no act or
thing done by Grantor shall invalidate the policy as against Beneficiary, shall
be endorsed with standard noncontributory mortgagee clauses in favor of and in
form acceptable to Beneficiary, and shall otherwise be in such form as shall be
reasonably acceptable to Beneficiary, so that at all times until the payment in
full of the Indebtedness, Beneficiary shall have and hold the said policy




                                      -13-
<PAGE>   18
and policies as further collateral for the payment of all Indebtedness. If
Grantor shall fail to obtain any such policy or policies required by
Beneficiary, or shall fail to assign and deliver the same to Beneficiary, then
Beneficiary may obtain such insurance and pay the premium or premiums therefor,
in which event Grantor shall, on demand of Beneficiary, repay such premium or
premiums to Beneficiary and such repayment shall be secured by the lien of this
Deed of Trust. If Grantor fails to maintain the level of insurance required
under this Deed of Trust, then Grantor shall, subject to Section 40 hereof,
indemnify Beneficiary to the extent that a casualty occurs and insurance
proceeds would have been available had such insurance been maintained.

         Grantor shall promptly provide to Beneficiary copies of any and all
notices (including notice of non renewal), claims, and demands which Grantor
receives from insurers of the Security.

         Any insurance required to be provided by Grantor under this Section 7
may be provided by means of a blanket policy insuring the Security as well as
other properties of Grantor.

         Effective from and after any Event of Default, Grantor hereby assigns
to Beneficiary all rights of Grantor in and to any unearned premiums on any
insurance policy required to be furnished by Grantor.

         8. Insurance/Condemnation Proceeds. Grantor hereby assigns to
Beneficiary all proceeds of any insurance or condemnation awards which Grantor
may be entitled to receive for loss or damage or taking of to the Security. In
the event of loss or damage to, or a taking of, the Security, the proceeds of
said insurance or condemnation award shall be payable to Beneficiary alone and
Grantor hereby authorizes and directs any affected insurance company or
government agency to make payment of the insurance proceeds or condemnation




                                      -14-
<PAGE>   19
awards directly to Beneficiary. In the event that any such insurance proceeds or
condemnation awards are paid directly to Grantor, Grantor shall make such
proceeds or awards available to Beneficiary within five (5) days of Grantor's
receipt thereof. No such loss or damage shall itself reduce the Indebtedness. No
settlement, adjustment, or compromise of any claim for a loss shall be effective
without Beneficiary's prior written approval. If Grantor fails to take
commercially reasonable action to settle, adjust, or compromise such loss or to
reasonably advise Beneficiary of the status of settlement negotiations, the
Beneficiary shall have the right, upon notice to Grantor, to adjust and
compromise such loss without the consent of the Grantor, to collect and receive
such proceeds or awards in the name of Beneficiary and Grantor and to endorse
the Grantor's name upon any check in payment thereof. Subject to the provisions
of Sections 9, 10, and 11 hereof, such proceeds or awards shall be applied first
toward reimbursement of all costs and expenses of the Beneficiary in collecting
said proceeds or awards, then toward payment of the Indebtedness or any portion
thereof, whether or not then due and payable, in whatever order Beneficiary may
elect, or the Beneficiary may, at its option, apply said insurance proceeds or
condemnation awards in whole or in part toward restoration of the Security for
which such insurance proceeds or condemnation awards shall have been paid.

         In the event of foreclosure of this Deed of Trust or other transfer of
title to the Security and extinguishment, in whole or in part, of the
Indebtedness, all right, title, and interest of Grantor in and to any proceeds
or payments in satisfaction of claims then pending, shall pass to the purchaser
or grantee notwithstanding the amount of any bid at such foreclosure sale.
Nothing contained herein shall prevent the accrual of interest as provided in
the Notes on any portion of the principal balance due under the Notes until such
time as the insurance proceeds or condemnation awards are actually received and
applied to reduce the principal balance outstanding.

         9. Restoration Following Fire and Other Casualty or Condemnation. In




                                      -15-
<PAGE>   20
the event of damage to the Security by reason of fire or other hazard or
casualty, Grantor shall give prompt written notice thereof to Beneficiary and
shall proceed with reasonable diligence to perform repair, replacement and/or
rebuilding work (hereinafter referred to as the "Work") to restore the Security
to its condition prior to such damage in full compliance with all legal
requirements. In the event of a taking by power of eminent domain or conveyance
in lieu thereof ("condemnation"), if restoration is feasible as reasonably
determined by Beneficiary, then Grantor shall proceed with reasonable diligence
to perform such restoration (also referred to as the "Work"). Before commencing
the Work, Grantor shall comply with the following requirements:

                  (a) Grantor shall furnish to Beneficiary complete plans and
         specifications for the Work, for Beneficiary's approval, which approval
         shall not be unreasonably withheld. Beneficiary shall notify Grantor of
         such approval or disapproval (and the reasons therefor) or its request
         for additional information within fifteen (15) business days after the
         receipt of such plans. Said plans and specifications shall bear the
         signed approval thereof by an architect satisfactory to Beneficiary and
         shall be accompanied by the architect's signed estimate, bearing the
         architect's seal, of the entire cost of completing the Work. Anything
         to the contrary provided in this Paragraph (a) notwithstanding, but
         without limiting any provision or requirement under other Paragraphs
         under this Section 9, Beneficiary shall not withhold its approval of
         any restoration plans that provide for restoration of the Improvements
         to substantially equivalent condition as existed prior to the
         applicable casualty.

                  (b) Grantor shall furnish to Beneficiary certified copies of
         all permits and approvals required by law in connection with the
         commencement and conduct of the Work.

                  (c) If Beneficiary requires, Grantor shall furnish to




                                      -16-
<PAGE>   21
         Beneficiary, prior to the commencement of the Work, a surety bond for
         or guaranty of completion of and payment for the Work, which bond or
         guaranty shall be in form satisfactory to Beneficiary and shall be
         signed by a surety or sureties, or guarantor or guarantors, as the case
         may be, who are acceptable to Beneficiary, and in either case for an
         amount not less than the architect's estimate of the entire cost of
         completing the Work, less the amount of insurance proceeds or
         condemnation award, if any, then held by Beneficiary and which
         Beneficiary shall have elected or be required to apply toward
         restoration of the Security as provided in Section 10 hereof. If, prior
         to commencement of the Work, the insurance proceeds or condemnation
         award has not yet been received, the amount of any surety bond required
         hereunder shall be based on Beneficiary's estimate of the insurance
         proceeds or condemnation award which will be forthcoming.

         Grantor shall not commence any of the Work, until Grantor shall have
complied with the above requirements, and thereafter Grantor shall perform the
Work diligently and in good faith in accordance with the plans and
specifications referred to in subsection (a) above.

         If, as provided in Section 10 hereof, Beneficiary shall have elected or
is required to apply any insurance proceeds or condemnation awards toward
restoration of the Security, then so long as the Work is being diligently
performed by Grantor in accordance with the provisions of this Deed of Trust,
Beneficiary shall disburse such insurance proceeds or condemnation awards to
Grantor from time to time during the course of the Work in accordance with the
following provisions:

                  A. The Work shall be in the charge of an experienced
         construction manager or general contractor reasonably satisfactory to
         Beneficiary with the consultation of an architect or engineer;




                                      -17-
<PAGE>   22
                  B. Each request for payment shall not be made more often than
         at thirty (30) day intervals on ten (10) business days prior notice to
         Beneficiary, and shall be accompanied by a certificate, satisfactory to
         Beneficiary, of the architect or engineer, dated not more than ten (10)
         days prior to the application for withdrawal of funds, stating:

                           (i)      that all of the Work for which payment is
                                    being requested is in place and has been
                                    completed in compliance with the approved
                                    plans and specifications and all applicable
                                    legal requirements;

                          (ii)      that the sum then requested to be withdrawn
                                    has been paid by Grantor and/or is justly
                                    due to contractors, subcontractors,
                                    materialmen, engineers, architects or other
                                    persons (whose names and addresses shall be
                                    stated) who have rendered or furnished
                                    certain services or materials for the Work
                                    and giving a brief description of such
                                    services and materials and the principal
                                    subdivisions or categories thereof and the
                                    respective amounts so paid or due to each of
                                    said persons in respect thereof and stating
                                    the progress of the Work up to the date of
                                    said certificate;

                         (iii)      that the sum then requested to be withdrawn,
                                    plus all sums previously withdrawn, does not
                                    exceed the cost of the Work insofar as
                                    actually accomplished up to the date of such
                                    certificate;

                          (iv)      that the remainder of the moneys held by
                                    Beneficiary will be sufficient to pay in
                                    full for the completion of the Work;




                                      -18-
<PAGE>   23
                           (v)      that no part of the cost of the services and
                                    materials described in the foregoing
                                    paragraph (ii) of this Clause B has been or
                                    is being made the basis of the withdrawal of
                                    any funds in any previous or then pending
                                    application; and

                          (vi)      that, except for the amounts, if any,
                                    specified in the foregoing paragraph (ii) of
                                    this Clause B to be due for services or
                                    materials, there is no outstanding
                                    indebtedness known, after due inquiry, which
                                    is then due and payable for work, labor,
                                    services or materials in connection with the
                                    Work which, if unpaid, might become the
                                    basis of a vendor's, mechanic's, laborer's
                                    or materialman's statutory or other similar
                                    lien upon the Security or any part thereof,
                                    except amounts for which the Grantor
                                    disputes and for which no lien has been
                                    filed, or if a lien has been filed, for
                                    which Grantor has provided bonding in an
                                    amount approved by Beneficiary.

                  C. Grantor shall deliver to Beneficiary satisfactory evidence
         that the Security and every part thereof, and all materials and all
         property described in the certificate furnished pursuant to the
         foregoing Clause B, are free and clear of all mortgages, liens, charges
         or encumbrances, except (a) encumbrances, if any, securing indebtedness
         due to persons (whose names and addresses and the several amounts due
         them shall be stated) specified in said certificate furnished pursuant
         to the foregoing Clause B, which encumbrances will be discharged upon
         disbursement of the funds then being requested, and (b) this Deed of
         Trust. Beneficiary shall accept as satisfactory evidence under this




                                      -19-
<PAGE>   24
         Clause C a certificate of a title insurance company acceptable to
         Beneficiary or an endorsement to Beneficiary's existing loan title
         policy insuring the lien of this Deed of Trust, dated as of the date of
         the making of the disbursement, confirming the foregoing.

                  D. Prior to the first advance, Grantor shall deliver to
         Beneficiary a survey of the Security dated as of a date within ten (10)
         days prior to the making of the advance (or revised to a date within
         ten days prior to the advance and periodically thereafter as
         Beneficiary shall reasonably request) showing no encroachments other
         than those, if any, acceptable to Beneficiary.

                  E. There shall be no Event of Default by Grantor under any of
         the Notes or under any other of the Loan Documents, or any state of
         facts existing which, with the passage of time or the giving of notice,
         or both, would constitute an Event of Default.

         Beneficiary at its option may waive any of the foregoing requirements.

         Upon compliance by Grantor with the foregoing Clauses A, B, C, D, and E
(except for such requirements, if any, as Beneficiary at its option may have
waived), Beneficiary shall, to the extent of the insurance proceeds or
condemnation award, if any, which Beneficiary shall have elected or be required
hereunder to apply to restoration of the Security, pay or cause to be paid to
the persons named in the certificate furnished pursuant to the foregoing
paragraph (i) of Clause B, the respective amounts stated in said certificate to
be due them, less ten percent (10%) retainage, or such other retainage
percentage as Beneficiary may approve ("Retainage"), and shall pay to Grantor
the amounts stated in said certificate to have been paid by Grantor, less
Retainage.




                                      -20-
<PAGE>   25
         If upon completion of the Work there shall be insurance proceeds or
condemnation awards held by Beneficiary over and above the amounts withdrawn
pursuant to the foregoing provisions, plus Retainage, then Beneficiary shall, as
long as there shall exist no Event of Default under any of the Notes or under
any of the Loan Documents, or any state of facts existing which, with the
passage of time or the giving of notice, or both, would constitute an Event of
Default, pay over such proceeds to Grantor; or if such Event of Default or state
of facts exists, then Beneficiary, may retain such proceeds or awards and apply
the same in reduction of the Indebtedness, in whatever order Beneficiary may
elect.

         Upon completion of Work, in addition to the requirements of the
foregoing Clauses A, B, C, D, and E Grantor shall promptly deliver to
Beneficiary:

                  (a) A written certificate of the architect or engineer that
         the Work has been substantially completed (subject only to punch list
         items) in a good and workmanlike manner in accordance with the approved
         plans and specifications;

                  (b) A written report and policy of a title insurance company
         acceptable to Beneficiary insuring the Security against mechanics' and
         materialmen's liens;

                  (c) A certificate by Grantor in form and substance
         satisfactory to Beneficiary, listing all costs and expenses in
         connection with the completion of the Work and the amount paid by
         Grantor with respect to the Work;

                  (d) A temporary certificate of occupancy and all other
         applicable certificates, licenses, consents and approvals issued by
         governmental agencies or authorities with respect to the Security and
         by the 




                                      -21-
<PAGE>   26
         appropriate Board of Fire Underwriters or other similar bodies acting
         in and for the locality in which the Security is situated, provided
         that within thirty (30) days after completion of the Work, Grantor
         shall obtain and deliver to Beneficiary a permanent certificate of
         occupancy for the Security.

         Upon receipt of the foregoing items, Beneficiary shall pay any
Retainage held by Beneficiary for the benefit of Grantor.

         10. Disposition of Condemnation or Insurance Proceeds. Subject to the
exceptions set forth below, Beneficiary, in its absolute discretion, may decide
whether and to what extent, if any, proceeds of insurance or condemnation will
be made available to Grantor for repair or restoration of the Security, but
Grantor shall effect such repair or restoration as provided above whether or not
Beneficiary makes any of such proceeds available for that purpose.
Notwithstanding the foregoing, Beneficiary agrees to make insurance or
condemnation proceeds available to Grantor for repair or restoration provided:

                  (i)      Not more than 40% of the net rentable area of the
                           Real Property is rendered untenantable, and, in the
                           case of a condemnation, the portion of the Security
                           not taken by condemnation has not, in Beneficiary's
                           sole opinion, been rendered economically nonviable by
                           the taking;

                 (ii)      There has been no Event of Default under the Loan
                           Documents for the twelve (12) months preceding the
                           damage or taking, and there does not then exist an
                           Event of Default, or any state of facts which, with
                           the passage of time or the giving of notice, or both,
                           would constitute an Event of Default;




                                      -22-
<PAGE>   27
                (iii)      Grantor can demonstrate to Beneficiary's satisfaction
                           that Grantor has the financial ability to make all
                           scheduled payments when due under the Loan Documents
                           during repair or restoration;

                 (iv)      Such damage or taking occurs prior to the last loan
                           year and the Work can be completed prior to the
                           Maturity Date;

                  (v)      Annual income from leases in place and approved by
                           Beneficiary that will survive completion of the Work
                           provide coverage of at least 1.30 times the annual
                           debt service;

                 (vi)      The Work will return the Improvements to
                           substantially the size, design, and utility as
                           existed immediately before the casualty; and

                (vii)      The proceeds are released under the
                           escrow/construction funding arrangements specified in
                           Section 9 hereof, provided, however, that if Grantor
                           can demonstrate to Beneficiary's reasonable
                           satisfaction that the insurance proceeds shall be
                           sufficient to restore and renovate the Security and
                           that the proceeds total less than $500,000, the
                           requirement of an escrow will be waived.

         If Beneficiary is not required and does not elect to make the proceeds
available for the Work, then such proceeds shall be applied to reduce the
Indebtedness in whatever order Beneficiary may elect. Any application of such
proceeds to the principal indebtedness evidenced by the Notes shall be at par
and shall cause a pro rata reduction in payments of interest and, if applicable,
principal, under the Notes; provided, however, that if there exists an Event of
Default, the prepayment fee as provided in the Notes shall




                                      -23-
<PAGE>   28
also be due.

         11. Fire and Other Casualty; Self-Help. If within one hundred twenty
(120) days after the occurrence of any damage to the Security in excess of
$100,000 or the condemnation of any portion of the Security, Grantor shall not
have submitted to Beneficiary and received Beneficiary's approval of plans and
specifications for the Work or shall not have obtained approval of such plans
and specifications from all governmental authorities whose approval is required,
or if, after such plans and specifications are approved by Beneficiary and all
such governmental authorities, Grantor shall fail to promptly commence the Work,
or if thereafter Grantor fails to perform the Work diligently or is delinquent
in the payment to mechanics, materialmen or others of the costs incurred in
connection with the Work, or, in the case of any loss or damage not in excess of
$100,000.00, if Grantor shall fail to complete the Work promptly, then, in
addition to all other rights herein set forth, and after giving Grantor twenty
(20) days written notice of the nonfulfillment of one or more of the foregoing
conditions Beneficiary, or any lawfully appointed receiver of the Security may
at its respective option, perform or cause the Work to be performed, and may
take such other steps as it deems advisable to perform the Work, and may enter
upon the Security for any of the foregoing purposes, and Grantor hereby waives,
for Grantor and all others holding under Grantor, any claim against Beneficiary
or such receiver arising out of anything done by Beneficiary or such receiver
pursuant to this Section, and Beneficiary may apply insurance proceeds (without
the need to fulfill the requirements of Section 9 hereof) to reimburse
Beneficiary, and/or such receiver for all amounts expended or incurred by them,
respectively, in connection with the performance of the Work, and any excess
costs shall be paid by Grantor to Beneficiary upon demand, with interest at the
Default Rate (hereinafter defined), and such payment shall be secured by the
lien of this Deed of Trust.




                                      -24-
<PAGE>   29
         12. Rent Insurance Proceeds. If Grantor shall promptly commence and
diligently perform the Work, and there shall be no Event of Default under the
Loan Documents, then Beneficiary shall each month pay to Grantor out of the rent
insurance proceeds held by Beneficiary a sum equal to that amount, if any, of
the rent insurance proceeds paid by the insurer which is allocable to the rental
loss for the preceding month. Beneficiary at its option may waive any of the
foregoing conditions to the payment of rent insurance proceeds. If Grantor does
not fulfill the foregoing conditions entitling Grantor to monthly disbursements
of rent insurance proceeds, then such rent insurance proceeds shall be held by
Beneficiary until the earlier to occur of satisfaction of such condition or the
occurrence of an Event of Default and acceleration of the Indebtedness at which
time may be applied by Beneficiary, at Beneficiary's option, to the payment of
the Indebtedness in whatever order Beneficiary may elect.

         13. Intentionally omitted.

         14. Repair; Alterations; Waste; Environmental. Grantor shall keep all
of the Security in good and substantial repair, and expressly agrees that it
will neither permit nor commit any waste upon the Security nor do any other act
or suffer or permit any act to be done, whereby the Security will become less
valuable or the lien hereof may be impaired and shall comply with all zoning
laws, building codes, subdivision laws, environmental laws, and other laws,
ordinances, rules and regulations made or promulgated by any government or
municipality, or by any agency thereof or by any other lawful authority, which
are now or may hereafter become applicable to the Security. Grantor shall repair
or restore any building now or hereafter under construction on the Security and
complete the same within a reasonable period of time. Grantor agrees not to
initiate or acquiesce in any zoning variance or reclassification, without
Beneficiary's prior written consent. Grantor shall not construct any additional
building or buildings or make any other 




                                      -25-
<PAGE>   30
improvements on the Land nor alter, remove or demolish any building or other
Improvements on the Land, without the prior written consent of Beneficiary.

         If Grantor suffers or permits any Event of Default to exist under this
Section, Beneficiary or a lawfully appointed receiver of the Security at its
option, from time to time, may perform, or cause to be performed, any and all
repairs and such other work as it deems necessary to bring the Security into
compliance with the provisions of this Section and may enter upon the Security
for any of the foregoing purposes, and Grantor hereby waives any claim against
Beneficiary and/or such receiver, arising out of such entry or out of any other
act carried out pursuant to this Section. Grantor shall upon demand repay to
Beneficiary and such receiver, with interest at the Default Rate, all amounts
expended or incurred by them, respectively, in connection with any action taken
pursuant to this Section, and such repayment shall be secured by the lien of
this Deed of Trust.

         Grantor represents and warrants that there are and at all times will be
at least the greater of (a) .8 parking spaces per 100 square feet of net
rentable area or (b) sufficient parking spaces to comply with applicable
government regulations as part of the Security.

         Grantor represents and warrants that Grantor has not used and will not
use and, to the best of Grantor's knowledge, no prior owner or current or prior
tenant, subtenant, or other occupant of all or any part of the Security has used
or is using Hazardous Materials (hereinafter defined) on, from or affecting the
Security in any manner that violates the Environmental Laws (hereinafter
defined), and that, no Hazardous Materials have been disposed of on the
Security, intentionally or unintentionally, directly or indirectly, by any
person whether related or unrelated to Grantor, nor have any Hazardous Materials
migrated onto the Security in either case, in violation of the Environmental
Laws.




                                      -26-
<PAGE>   31
         For purposes of this Deed of Trust, the following terms shall have the
definition set forth:

         "Hazardous Materials" shall mean and include those elements, materials,
compounds, mixtures, wastes or substances which are contained in any list of
hazardous substances adopted by the United States Environmental Protection
Agency (the "EPA") or any list of toxic pollutants designated by Congress or the
EPA or which are defined as hazardous, toxic, pollutant, infectious, flammable
or radioactive by any of the Environmental Laws (hereinafter defined) and,
whether or not included in such lists, shall be deemed to include all products
or substances containing petroleum, asbestos, and polychlorinated biphenyls.

         "Environmental Laws" shall mean and include any Federal, State, or
local statute, law, ordinance, code, rule, regulation, order, or decree
regulating or relating to protection of human health or the environment, or
regulating or imposing liability or standards of conduct concerning the use,
storage, treatment, transportation, manufacture, refinement, handling,
production or disposal of any hazardous, toxic, or dangerous waste, substance,
element, compound, mixture or material, as now or at any time hereafter in
effect including, without limitation, Colorado Air Quality Control Act, C.R.S.
Sections 25-7-101 et seq.; the Colorado Hazardous Materials Transportation Act
of 1987, C.R.S. Sections 43-6-101 et seq.; the Colorado Nuclear Materials
Transportation Act of 1986, C.R.S. Sections 40-2.2-101 et seq.; the Colorado
Water Quality Control Act, C.R.S. Sections 25-8-101 et seq.; the Colorado
Underground Storage Tank Act, C.R.S. Sections 8-20-501 et seq., 8-20-601 et
seq., and 25-18-101 et seq.; the Colorado Hazardous Waste Act, C.R.S. Sections
25-15-101 et seq.; the Colorado Hazardous Materials Incident Act, C.R.S.
Sections 29-22-101 et seq. the Federal Comprehensive Environmental Response,
Compensation and Liability Act, as amended, 42 U.S.C. Sections 9601 et seq., the
Superfund Amendments and Reauthorization Act, 42 U.S.C. Sections 9601 et seq.,
the Federal Oil Pollution Act of 1990, 33 U.S.C. Sections 2701, et seq., the
Federal Toxic Substances Control Act, 15 U.S.C. Sections 2601 et seq., the
Federal Resource Conservation and Recovery Act as amended, 42 U.S.C. Sections
6901 




                                      -27-
<PAGE>   32
et seq., the Federal Hazardous Materials Transportation Act, 49 U.S.C. Sections
1801 et seq., the Federal Clean Air Act 42 U.S.C. Sections 7401 et seq., the
Federal Water Pollution Control Act, 33 U.S.C. Sections 1251 et seq., the River
and Harbors Act of 1899, 33 U.S.C. Sections 401 et seq., the National Emission
Standard for Hazardous Air Pollutants for Asbestos, 40 C.F.R. Sections 61.140 et
seq., the OSHA Construction Standard, 29 C.F.R. Sections 1926.1001 et seq., and
all rules and regulations of the EPA, or any other state or federal department,
board, or agency, or any other agency or governmental board or entity having
jurisdiction over the Security, as any of the foregoing have been, or are
hereafter amended.

         Grantor represents and warrants that, to the best of Grantor's
knowledge and belief, the Security does not contain, and has not in the past
contained, any asbestos-containing material in friable form and there is no
current or potential airborne contamination of the Security by asbestos fiber,
including any potential contamination that would be caused by maintenance or
tenant finish activities in the Security.

         Grantor represents and warrants that it has not received any notice
that the soil, surface water, and ground water of or on the Security are not
free from any spills of oil or other solid or liquid waste, toxic or hazardous
substance or contaminant, and Grantor, after making reasonable inquiry, has no
knowledge of any such spill.

         In the event that any investigation, site monitoring, containment,
clean-up, removal, restoration or other remedial work of any kind or nature (the
"Remedial Work") is reasonably necessary or desirable under any applicable
local, state or federal law or regulation, any judicial order, or by any
governmental entity because of, or in connection with, the current or future
presence, suspected presence, release or suspected release of a Hazardous
Material in or about the air, soil, ground water, surface water or soil vapor
at, on, about, under or within the Security (or any portion




                                      -28-
<PAGE>   33
thereof), Grantor shall within thirty (30) days after written demand for
performance thereof by Beneficiary (or such shorter period of time as may be
required under any applicable law, regulation, order or agreement), commence and
thereafter diligently prosecute to completion, all such Remedial Work. All
Remedial Work shall be performed by contractors approved in advance by
Beneficiary which approval shall not be unreasonably withheld or delayed, and
under the supervision of a consulting engineer approved by Beneficiary. All
costs and expenses of such Remedial Work shall be paid by Grantor including,
without limitation, Beneficiary's reasonable attorneys' fees, paralegal fees and
costs incurred in connection with monitoring or review of such Remedial Work.
Such costs and expenses to be borne by Grantor shall not include those relating
to Beneficiary's employment of contractors and consulting engineers other than
those approved pursuant to the foregoing, unless such employment is reasonably
necessary and justifiable under the then existing circumstances. In the event
Grantor shall fail to timely prosecute to completion, such Remedial Work,
Beneficiary may, but shall not be required to, cause such Remedial work to be
performed and all costs and expenses thereof, or incurred in connection
therewith, shall become part of the Indebtedness.

         Grantor shall provide Beneficiary with prompt written notice (a) upon
Grantor's becoming aware of any release or threat of release of any Hazardous
Materials upon, under or from the Security; (b) upon Grantor's receipt of any
notice from any federal, state, municipal or other governmental agency or
authority in connection with any Hazardous Materials located upon or under or
emanating from the Security; and (c) upon Grantor's obtaining knowledge of any
incurrence of expense by any governmental agency or authority in connection with
the assessment, containment or removal of any Hazardous Materials located upon
or under or emanating from the Security.

         15. Intentionally Omitted.




                                      -29-
<PAGE>   34
         16. Independence of Security. Trustor shall not by act or omission
permit any building or other improvement on premises not subject to the lien of
this Deed of Trust to rely on the Security or any part thereof or any interest
therein to fulfill any municipal or governmental requirement, and Trustor hereby
assigns to Beneficiary any and all rights to give consent for all or any portion
of the Security or any interest therein to be so used. Similarly, no part of the
Security shall rely on any premises not subject to the lien of this Deed of
Trust or any interest therein to fulfill any governmental or municipal
requirement. Trustor shall not by act or omission impair the integrity of the
Security as a single zoning lot, and as one or more complete tax parcels,
separate and apart from all other premises. Any act or omission by Trustor which
would result in a violation of any of the provisions of this Section shall be
void. Trustor shall, if it has not already been accomplished, obtain a
separation of the Real Property from all other adjacent lands, and the same
shall be promptly accomplished, and evidenced in the appropriate public records.
In any event, if such separation is not accomplished and evidenced on the
completed assessment roll of the Denver County Assessor for the tax year 1996 as
and when such assessment roll is submitted by the Assessor to the Clerk of the
Board of Supervisors of said County, then Beneficiary may at its option, with or
without notice, declare all sums secured by this Deed of Trust to be immediately
due and payable and avail itself of any and all remedies provided for herein
upon the occurrence of an Event of Default; and further, Beneficiary may at its
option, in addition or in the alternative to the above, should Trustor fail to
pay the same before they become delinquent, advance the necessary monies to pay
all taxes, assessments, and other charges levied or assessed on or against the
Real Property and any other parcel or parcels adjacent thereto, whether or not
such other adjacent parcels be otherwise part of or subject to the terms and
conditions of this Deed of Trust, and all such monies so advanced shall be
secured by the lien of this Deed of Trust and shall be subject to the same terms
and conditions as provided herein.




                                      -30-
<PAGE>   35
         17. No Other Liens; Secondary Financing. Grantor shall not consent,
agree to, or permit any mortgage, lien, or security interest upon or affecting
the Security or any part thereof except as granted or permitted in this Deed of
Trust and any other lien or security interest granted to Beneficiary.

         Notwithstanding the foregoing provisions, Grantor shall have the right
to borrow additional funds from another lender and further encumber the Real
Property with a secondary lien provided:

                  (i)      at the time of Grantor's request and at the time of
                           the financing transaction closing there exists no
                           uncured default for which notice is not required nor
                           any other uncured default for which notice has been
                           previously given to Grantor;

                 (ii)      the proposed secondary financing shall be from an
                           Institutional Investor;

                (iii)      the aggregate current Debt Service Coverage, as
                           hereinafter defined in Section 25, on the aggregate
                           amount of the Notes plus Beneficiary's proposed
                           additional financing exceeds 1.5 times;

                 (iv)      the proposed secondary financing shall not be given
                           in satisfaction of, or to evidence, judgments or
                           claims against Grantor, nor shall any security
                           interest (mortgage) securing the proposed financing
                           be cross-defaulted or cross-collateralized with any
                           other security interest in any other property;

                  (v)      at least 30 days prior to the closing of the proposed




                                      -31-
<PAGE>   36
                           secondary financing Grantor shall provide Beneficiary
                           with all of the material provisions of such financing
                           including without limitation the proposed date of
                           closing and the name, background and address of the
                           proposed lender, and the principal amount, rate,
                           periodic payments, term and other salient features of
                           the financing;

                 (vi)      the additional financing must not call for an accrual
                           of interest or additional principal and all payments
                           must be on a current pay basis, and interest on such
                           financing must be payable at a fixed rate or floating
                           rate (if subject to a maximum interest rate cap such
                           that the debt service coverage requirement under
                           subparagraph (iii) above will be satisfied at the
                           maximum rate);

                (vii)      the aggregate loan-to-value ratio of the aggregate
                           principal amount of the Notes and the proposed
                           secondary financing must not exceed 65%, and
                           Beneficiary shall be provided with such reasonable
                           information as Beneficiary may require to determine
                           the same;

               (viii)      Grantor shall pay for all of Beneficiary's costs and
                           expenses associated with such financing, including
                           without limitation, cost of the appraisal, attorneys'
                           fees charged by Beneficiary's staff counsel, special
                           counsel or outside counsel; and

                 (ix)      the secondary lender shall enter into an
                           intercreditor agreement with Beneficiary to the
                           following effect:

                           (a)      the secondary lender waives any right to
                                    marshaling or 




                                      -32-
<PAGE>   37
                                    to assert priority over future advances, if
                                    any, provided for in the loan documents;

                           (b)      the secondary lender agrees to be bound by
                                    any extensions or modifications of the Loan
                                    Documents;

                           (c)      the secondary lender agrees that Beneficiary
                                    shall in all cases be paid all sums then due
                                    under the Loan Documents before the
                                    secondary lender receives any sums then due
                                    under the secondary financing;

                           (d)      the secondary lender agrees to notify
                                    Beneficiary of any default by Grantor under
                                    such secondary financing loan documents and
                                    further agrees not to accelerate or to
                                    exercise any rights or remedies with respect
                                    to the Real Property for a period of ninety
                                    (90) days after Beneficiary's receipt of
                                    such notice;

                           (e)      the secondary lender agrees that it will not
                                    transfer its interest without the prior
                                    written consent of Beneficiary and that any
                                    transferee will enter into and assume its
                                    obligations under the intercreditor
                                    agreement;

                           (f)      the subordinate lender shall expressly
                                    acknowledge the priority of the liens and
                                    security interest of the Loan Documents over
                                    the liens and security interests of the
                                    secondary financing loan documents, and
                                    shall agree to enter into non-disturbance
                                    agreements with respect to all leases of
                                    space in the Building entered into after the
                                    date of such secondary lien, satisfactory in
                                    form and substance to Beneficiary, which
                                    shall be 




                                      -33-
<PAGE>   38
                                    appropriately recorded; and

                           (g)      the secondary lender will not take an
                                    adverse position to Beneficiary in the event
                                    of the bankruptcy or insolvency of Grantor.

                  (x)      The Loan Documents will provide that any default
                           under the second mortgage shall constitute a default
                           under the Loan.

         Notwithstanding the foregoing, no secondary financing shall be
permitted during any earnout period or prior to the time any additional
collateral, including without limitation any guarantee, letter of credit,
escrowed amounts (other than tax escrow), master leases by Grantor or any other
collateral posted by Grantor as security for the Deed of Trust has been released
or collected.

         "Institutional Investor" is defined as any bank, savings and loan
         association, trust company, insurance company, pension fund, investment
         advisor, credit union, real estate investment trust or charitable
         foundation actively engaged in acquiring or financing major commercial
         real estate properties and approved by Beneficiary, such approval not
         to be unreasonably withheld.

         Grantor will promptly pay and discharge any and all amounts which are
now or hereafter become liens against the Security whether or not superior to
the lien hereof or to any assignment of rents and leases given to Beneficiary.

         The covenants of this Section shall survive any foreclosure and sale of
the Security and any conveyance thereof by deed in lieu of foreclosure with
respect to any such liens in existence as of the date of transfer of title.




                                      -34-
<PAGE>   39
         18. Management. During the term of the loan secured hereby, Grantor
shall at all times retain a professional management company to operate and
manage the Security. A written management agreement shall be required and the
management company and the form and content of the management agreement shall be
subject to Beneficiary's approval, which shall not be unreasonably withheld or
delayed. No change in such management shall be made without the prior written
approval of Beneficiary which shall not be unreasonably withheld or delayed, and
any attempted change in management without such consent shall be void. The
management of the Security, including any wholly owned and controlled affiliate
of Grantor and any proposal for direct management by Grantor, must be
satisfactory to and approved by Beneficiary, provided, however, Beneficiary
shall not unreasonably withhold approval of any affiliate of Grantor or direct
management by Grantor. Beneficiary acknowledges that a proposed affiliate of
Grantor may not have managed or be managing other properties similar to the
Security and agrees that Beneficiary will not withhold its consent solely on
that basis if, in Beneficiary's sole judgment, such affiliate has adequate
resources and appropriately experienced employees to effectively manage the
Security. The management agreement must provide that it is subordinate to the
lien of this Deed of Trust or terminable without cause upon thirty (30) days'
prior written notice, and may not be modified or amended in any material manner
without Beneficiary's prior written approval. Management fees shall not
constitute a lien upon the Security and Beneficiary shall have no liability for
payment of such fees. The manager under the management agreement and under any
successor management agreement shall agree to termination thereof upon
foreclosure or upon Beneficiary's otherwise taking control of the Security.
Subject to Beneficiary's approval of the form of its management agreement,
Beneficiary hereby approves Hines Interests Limited Partnership as the manager
of the Security.

         19. Intentionally omitted.




                                      -35-
<PAGE>   40
         20. Sidewalks, Municipal Charges. Grantor will promptly pay and
discharge any and all license fees and similar charges, with penalties and
interest thereon, which may be imposed by the municipality in which the Security
is situated, for the use of vaults, chutes, areas and other space beyond the lot
line and under or abutting the public sidewalks in front of or adjoining the
Security, and Grantor will promptly cure any violation of law and comply with
any order of such municipality respecting the repair, replacement or condition
of the sidewalk or curb in front of or adjoining the Security, and in default
thereof Beneficiary may, upon five (5) days notice to Grantor, pay any and all
such license fees or similar charges, with penalties and interest thereon, and
the charges of the municipality for such repair or replacement, and any amount
so paid or advanced by Beneficiary and all costs and expenses incurred in
connection therewith (including, without limitation, attorneys' fees), with
interest thereon at the default rate specified in the Notes, shall be a demand
obligation of Grantor to Beneficiary, and, to the extent permitted by law, shall
be added to the Indebtedness and shall be secured by the lien of this Deed of
Trust.

         21. Ground Lease.

                  (a)      Grantor hereby represents and warrants that it holds
                           all right, title, and interest in, to, and under the
                           Ground Lease, both as to the lessor and lessee
                           thereunder, and all representations, warranties, and
                           agreements made hereunder are being made by Grantor
                           in its capacity as both lessor and lessee. Grantor
                           hereby agrees that the Ground Lease, together with
                           all extensions, replacements, and modifications
                           thereof, are and at all times shall be subject and
                           subordinate to this Deed of Trust and all terms
                           hereof and, to the extent that any provisions of the
                           Ground Lease are in conflict with any provisions of
                           this Deed of Trust or any other Loan Documents,




                                      -36-
<PAGE>   41
                           the provisions of this Deed of Trust and the other
                           Loan Documents shall control and prevail.

                  (b)      Grantor shall at all times promptly and faithfully
                           keep, observe and perform in all material respects,
                           or cause to be kept, observed and performed in all
                           material respects, all the covenants, agreements and
                           conditions contained in the Ground Lease, to be kept,
                           observed and performed, and shall in all material
                           respects conform to and comply with the terms and
                           conditions of the Ground Lease, and Grantor shall not
                           do or permit any thing to be done, the doing of
                           which, or refrain from doing any thing, the omission
                           of which, would impair or tend to impair the security
                           of this Deed of Trust, or would be grounds for a
                           termination the Ground Lease or a declaration of a
                           forfeiture of any interest in the Ground Lease.

                  (c)      Grantor shall not modify, change, supplement, alter
                           or amend the Ground Lease in any respect, either
                           orally or in writing, and Grantor shall not
                           terminate, cancel, sever or surrender, or suffer the
                           termination, cancellation, severance or surrender of,
                           the Ground Lease or the ground leasehold estate, and
                           shall not in any way release or discharge any party
                           to or under the Ground Lease, or any of its
                           successors or assigns, of or from any obligations,
                           covenants, conditions and agreements by said party to
                           be kept, observed or performed. Grantor hereby
                           expressly assigns, releases, relinquishes and
                           surrenders unto Beneficiary all its right, power and
                           authority to cancel, terminate, surrender, sever,
                           amend, modify or alter in any respect the terms and
                           provisions of the Ground Lease, the leasehold estate,
                           and any 




                                      -37-
<PAGE>   42
                           attempt on the part of Grantor to exercise any such
                           right without the prior written consent of
                           Beneficiary shall be void and of no force and effect.

                  (d)      No release or forbearance of any of Grantor's
                           obligations under the Ground Lease pursuant to the
                           terms thereof, or otherwise, shall release Grantor of
                           its obligations under this Deed of Trust or any
                           instrument supplemental hereto.

                  (e)      Grantor shall give Beneficiary immediate notice of
                           any default under the Ground Lease and Grantor shall
                           furnish to Beneficiary immediately any and all
                           information which Beneficiary may request concerning
                           the performance and observance of all covenants,
                           agreements and conditions contained in the Ground
                           Lease, observed and performed and concerning the
                           compliance with all terms and conditions of the
                           Ground Lease. Grantor hereby authorizes Beneficiary
                           or its representatives to make investigations and
                           examinations concerning such performance, observance
                           and compliance, and Grantor, upon request, shall
                           promptly deposit with Beneficiary any and all
                           documentary evidence relating to such performance,
                           observance and compliance and copies of any and all
                           notices, communications, plans, specifications or
                           other instruments or documents received or given by
                           Grantor in any way relating to or affecting the
                           Ground Lease which may concern or affect the estate
                           of the lessor or the lessee in or under the Ground
                           Lease or in the leased premises thereby demised.

                  (f)      In the event of any failure by Grantor to keep,
                           observe or perform any covenant, agreement or
                           condition contained in the 




                                      -38-
<PAGE>   43
                           Ground Lease or to comply with the terms and
                           conditions of the Ground Lease, Beneficiary may, at
                           Beneficiary's option, perform, observe or comply with
                           the Ground Lease on behalf of Grantor, and any such
                           performance, observance or compliance by Beneficiary
                           shall not remove or waive, as between Grantor and
                           Beneficiary, the corresponding Event of Default under
                           the terms of this Deed of Trust. Any amount so
                           advanced by Beneficiary to effectuate such
                           performance, observance or compliance and all costs
                           and expenses incurred in connection therewith
                           (including, without limitation, attorneys' fees),
                           with interest thereon at the Default Rate, shall be a
                           demand obligation of Grantor to Beneficiary, and, to
                           the extent permitted by law, shall be added to the
                           Indebtedness and shall be secured by this Deed of
                           Trust.

                  (g)      Grantor shall not, without Beneficiary's prior
                           written consent, elect to treat the Ground Lease or
                           the leasehold estate as terminated under Subsection
                           365(h)(1) of the Bankruptcy Code, after rejection or
                           disaffirmance of the Ground Lease by the lessor
                           thereunder, or its successors and assigns, or by any
                           trustee of any such party, and any such election made
                           without such consent shall be void and ineffective.

                  (h)      Grantor hereby unconditionally assigns, transfers and
                           sets over unto Beneficiary all of Grantor's claims
                           and rights to the payment of damages that may
                           hereafter arise as a result of any rejection or
                           disaffirmance of the Ground Lease by the lessor
                           thereunder, or its successors and assigns, or by any
                           trustee of any such party pursuant to the Bankruptcy
                           Code. Beneficiary shall have and is hereby granted
                           the right to proceed, in its own name or in the name
                           of Grantor, in 




                                      -39-
<PAGE>   44
                           respect of any claim, suit, action or proceeding
                           relating to the rejection or disaffirmance of the
                           Ground Lease (including, without limitation, the
                           right to file and prosecute, to the exclusion of
                           Grantor, any proofs of claim, complaints, motions,
                           applications, notices and other documents) in any
                           case in respect of such lessor or any of its
                           successors and assigns, under the Bankruptcy Code.
                           This assignment constitutes a present, irrevocable
                           and unconditional assignment of the foregoing claims,
                           rights and remedies, and shall continue in effect
                           until all of the Indebtedness shall have been
                           satisfied and discharged in full. Any amounts
                           received by Beneficiary as damages arising out of any
                           such rejection or disaffirmance of a Ground Lease
                           shall be applied first to all costs and expenses of
                           Beneficiary (including, without limitation,
                           attorneys' fees) in connection with the exercise of
                           its rights under this subparagraph and then, in such
                           manner as Beneficiary shall determine, to the
                           reduction of the Indebtedness, whether or not then
                           due, and the balance, if any, shall then be paid to
                           Grantor.

                  (i)      In the event, that, pursuant to Subsection 365(h)(2)
                           of the Bankruptcy Code, Grantor seeks to offset
                           against the rent or other payments payable under the
                           Ground Lease, the amount of any damages caused by the
                           nonperformance by the lessor thereunder, or its
                           successors and assigns, of such party's obligations
                           under the Ground Lease after rejection or
                           disaffirmance thereof under the Bankruptcy Code,
                           Grantor shall, prior to effecting such offset, notify
                           Beneficiary of Grantor's intent to do so, setting
                           forth the amounts proposed to be so offset and the
                           basis therefor. Beneficiary shall




                                      -40-
<PAGE>   45
                           have the right to object to all or any part of such
                           offset, and, in the event of such objection, Grantor
                           shall not effect any offset of the amounts so
                           objected to by Beneficiary. If Beneficiary shall have
                           failed to object as aforesaid within ten (10)
                           business days after such notice, Grantor may proceed
                           to effect such offset in the amounts set forth in
                           such notice. Neither Beneficiary's failure to object
                           as aforesaid nor any objection or other communication
                           between Grantor and Beneficiary relating to such
                           offset shall constitute an approval by Beneficiary of
                           any such offset. Grantor shall indemnify and hold
                           Beneficiary harmless from and against any and all
                           claims, demands, actions, suits, proceedings,
                           damages, losses, costs and expenses of every nature
                           whatsoever (including, without limitation, attorneys'
                           fees) arising from or relating to any such offset by
                           Grantor.

                  (j)      Grantor shall, promptly after obtaining knowledge
                           thereof, give written notice to Beneficiary of any
                           actual or contemplated filing by or against the
                           lessor under the Ground Lease, or its successors and
                           assigns, of a petition under the Bankruptcy Code, and
                           use its best efforts to give prompt oral notice to
                           Beneficiary of such actual or contemplated filing.
                           The aforesaid written notice shall set forth any
                           information available to Grantor concerning the date
                           on which such petition was filed or is expected to be
                           filed, and the relief sought therein. Grantor shall
                           promptly after receipt thereof, deliver to
                           Beneficiary any and all notices, summonses,
                           pleadings, applications and other documents received
                           by Grantor in connection with any such petition and
                           any proceedings relating thereto.




                                      -41-
<PAGE>   46
                  (k)      In the event that any action, proceeding, motion or
                           notice shall be commenced or filed in respect of
                           either party under the Ground Lease, or its
                           successors and assigns, or the leased premises, or
                           the Security or any part thereof, in connection with
                           any cause under the Bankruptcy Code, Beneficiary
                           shall have, and is hereby granted, the option, to the
                           exclusion of Grantor exercisable upon notice from
                           Beneficiary to Grantor, to conduct and control any
                           such litigation with counsel of Beneficiary's choice.
                           Beneficiary may proceed, in its own name or in the
                           name of Grantor, in connection with any such
                           litigation, and Grantor agrees to execute any and all
                           powers, pleadings, authorizations, consents and other
                           documents required by Beneficiary in connection
                           therewith. Notwithstanding the foregoing, Grantor
                           shall be entitled to participate in any such actions
                           or proceedings, at its own expense and with counsel
                           of its choice, if and so long as Beneficiary shall be
                           satisfied that Grantor's participation therein and
                           the positions asserted by Grantor in connection
                           therewith will not materially impair the security of
                           this Deed of Trust. Grantor shall, upon demand, pay
                           to Beneficiary all costs and expenses (including,
                           without limitation, attorneys' fees) paid or incurred
                           by Beneficiary in connection with the prosecution or
                           conduct of any such proceedings, together with
                           interest at the Default Rate, and, to the extent
                           permitted by law, such costs, expenses and interest
                           shall be added to the Indebtedness and shall be
                           secured hereby. Grantor shall not, without the prior
                           written consent of Beneficiary, commence any action,
                           suit, proceeding or case, or file any application or
                           make any motion, in respect of the Ground Lease in
                           any such case under the Bankruptcy Code.




                                      -42-
<PAGE>   47
                  (l)      In the event that a petition under the Bankruptcy
                           Code shall be filed by or against Grantor and Grantor
                           or any trustee of Grantor shall decide to reject or
                           disaffirm the Ground Lease pursuant to the Bankruptcy
                           Code, Grantor shall give Beneficiary at least ten
                           (10) business days prior written notice of the date
                           on which application shall be made to the court for
                           authority to reject or disaffirm the Ground Lease.
                           Beneficiary shall have the right, but not the
                           obligation, to serve upon Grantor or such trustee
                           within such ten (10) day period a notice stating that
                           (i) Beneficiary demands that Grantor or such trustee
                           assume and assign the Ground Lease to Beneficiary
                           pursuant to Section 365 of the Bankruptcy Code, and
                           (ii) Beneficiary covenants to cure, or provide
                           adequate assurance of prompt cure of, all defaults
                           and provide adequate assurance of future performance
                           under the Ground Lease. In the event that Beneficiary
                           serves such notice upon Grantor or such trustee,
                           neither Grantor nor such trustee shall seek to reject
                           or disaffirm the Ground Lease and Grantor and such
                           trustee shall comply with such demand within thirty
                           (30) days after such notice shall have been given,
                           subject to Beneficiary's performance of such
                           covenant.

                  (m)      In the event that a petition under the Bankruptcy
                           Code shall be filed by or against Grantor, and if
                           within thirty (30) days after the date of filing of
                           such petition neither Grantor nor any trustee of
                           Grantor shall take any affirmative action to assume,
                           reject or disaffirm the Ground Lease pursuant to the
                           Bankruptcy Code, then Beneficiary shall have the
                           right, but not the obligation, to serve upon Grantor
                           or such trustee a notice stating that (i) Beneficiary
                           demands 




                                      -43-
<PAGE>   48
                           that Grantor or such trustee assume and assign the
                           Ground Lease to Beneficiary pursuant to Section 365
                           of the Bankruptcy Code, and (ii) Beneficiary
                           covenants to cure, or provide adequate assurance of
                           prompt cure of, all defaults and provide adequate
                           assurance of future performance under the Ground
                           Lease. In the event that Beneficiary serves such
                           notice upon Grantor or such trustee, either Grantor
                           or such trustee shall comply with such demand within
                           fifteen (15) days after such notice shall have been
                           given, subject to Beneficiary's performance of such
                           covenant.

                  (n)      Grantor hereby assigns, transfers and sets over to
                           Beneficiary a nonexclusive right to apply to the
                           Bankruptcy Court under Subsection 365(d)(4) of the
                           Bankruptcy Code for an order extending the period
                           during which the Ground Lease may be rejected,
                           disaffirmed or assumed after the entry of any order
                           for relief in respect of Grantor under Chapter 7 of
                           the Bankruptcy Code.

         22. Future Leases. Grantor will not hereafter make any lease to any
tenant, or amend, modify, terminate, renew or extend any lease (other than a
renewal to which a tenant is entitled under the terms of an existing lease or
contained in a lease that is subsequently approved by Beneficiary), affecting
the Security unless Beneficiary shall first consent in writing to the terms of
said lease and the form of the lease, which consent shall not be unreasonably
withheld.

         Notwithstanding the above, office and retail leases, lease amendments,
modifications, terminations, renewals or extensions that satisfy all of the
following conditions shall be deemed to have been pre-approved by Beneficiary:




                                      -44-
<PAGE>   49
                  (a)      The lease shall be on the standard form approved by
                           Beneficiary except for reasonable negotiated changes;
                           and

                  (b)      The gross leasable area of the space demised under
                           the lease shall be equal to or less than the square
                           footage on one full floor (approximately 25,000
                           s.f.); and

                  (c)      The term of the lease shall be less than or equal to
                           11 years (including renewal or extension options);
                           and

                  (d)      The effective rent is in compliance with a schedule
                           of rents previously approved, and from time to time
                           updated, in writing by Beneficiary; and

                  (e)      The lease shall not grant an option or right of first
                           refusal with respect to purchase of all or any
                           portion of the Real Property; and

                  (f)      With respect to any obligation to rebuild the
                           premises in the event of casualty, there has been no
                           modification to the provisions of the form lease
                           which conflicts with the provisions hereof regarding
                           repair and restoration after a casualty or
                           condemnation.

         Provided that there exists no uncured default for which notice is not
required nor any other uncured default for which notice has been previously
given, Grantor may update the schedule of rents described in subparagraph (d),
above, from time to time with Beneficiary's approval, which approval shall not
be unreasonably withheld so long as the rents reflected in such schedule are
consistent with the fair market rental value for comparable space in the Denver
CBD.




                                      -45-
<PAGE>   50
         All leases must be subordinate to the lien of this Deed of Trust unless
Beneficiary otherwise specifies. Each lease must contain a provision that, upon
notice to tenant by Beneficiary, the lease shall become superior, in whole or in
part, to the lien of this Deed of Trust. Without limiting the foregoing,
Beneficiary hereby reserves the right to subordinate this Deed of Trust to any
lease subsequently made by recording with the Clerk and Recorder of the City and
County of Denver in which this Deed of Trust is recorded a declaration to that
effect, executed by Beneficiary, which declaration once so recorded shall be
binding upon the tenant under such lease and such tenant's successors and
assigns. Beneficiary may require a subordination, non-disturbance and attornment
agreement, in the form attached hereto as Exhibit B (or with such modifications
as Beneficiary may reasonably require) for each lease executed subsequent to the
Deed of Trust. Beneficiary agrees, upon Grantor's request, to enter into a
subordination, non-disturbance and attornment agreement on such form with any
tenant whose lease is approved by Lender and which covers more than 25,000
square feet of the Real Property.

         Grantor will furnish to Beneficiary a true and complete copy of each
lease, amendment, modification, extension, or renewal of lease, hereafter made
by Grantor with respect to space in the Security within ten (10) days after
delivery of each such lease, amendment, modification, extension, or renewal by
the parties thereto. Grantor shall also furnish to Beneficiary an original
mortgagee attornment agreement executed by each tenant and an original estoppel,
addressed to Beneficiary, from each tenant in form and substance satisfactory to
Beneficiary.

         Grantor will from time to time upon demand of Beneficiary, confirm in
writing the assignment to Beneficiary of any or all leases of the Land and space
in the Improvements, and such written confirmation shall be in such form as
Beneficiary shall require and as shall be necessary to make the same recordable.




                                      -46-
<PAGE>   51
         23. Intentionally Omitted.

         24. Leases; Foreclosure. Any proceedings or other steps taken by
Beneficiary to foreclose this Deed of Trust, or otherwise to protect the
interests of Beneficiary hereunder, shall not operate to terminate the rights of
any present or future tenant of space in the Improvements, notwithstanding that
said rights may be subject and subordinate to the lien of this Deed of Trust,
unless Beneficiary specifically elects otherwise in the case of any particular
tenant. The failure to make any such tenant a defendant in any such foreclosure
proceeding and to foreclose such tenant's rights will not be asserted by Grantor
or any other defendant in such foreclosure proceeding and to foreclose such
tenant's rights will not be asserted by Grantor or any other defendant in such
foreclosure proceeding as a defense to any proceeding instituted by Beneficiary
to foreclose this Deed of Trust or otherwise protect the interests of
Beneficiary hereunder.

         25. One-Time Transfer of Ownership. Notwithstanding the provisions of
Section 26 below, Grantor shall have the right to a one-time sale, transfer or
assignment in whole or in part of its interest in the Security to any party of
equal qualification and credit-worthiness provided:

                  (i)      at the time of Grantor's request and at the time of
                           the transfer there exists no uncured default for
                           which notice is not required nor any other uncured
                           default for which notice has been previously given to
                           Grantor;

                 (ii)      a property inspection by Beneficiary or Beneficiary's
                           designee shows that all reasonably necessary
                           maintenance on or damage or destruction to the Real
                           Property has been completed or repaired;




                                      -47-
<PAGE>   52
                (iii)      the proposed transferee shall be a Qualified Real
                           Estate Investor;

                 (iv)      the aggregate Debt Service Coverage on the Loan and
                           any applicable secondary financing exceeds 1.7 times;

                  (v)      the proposed transferee (or any Affiliated Party of
                           such transferee) must own and manage a minimum of 3
                           million net rentable square feet of general purpose
                           office space including major downtown office
                           properties;

                 (vi)      at least 30 days prior to such a transfer Grantor
                           must provide Beneficiary with all of the material
                           provisions of such transfer including without
                           limitation the proposed date of transfer, the name,
                           net worth, background and address of the proposed
                           transferee, financial statements for the proposed
                           transferee satisfactory to Beneficiary, and the
                           purchase price;

                (vii)      Omitted;

               (viii)      such transfer may only occur during the first four
                           years of the Term, or, if Grantor has elected to
                           extend the Term, as provided in that certain
                           Extension Option Agreement of even date herewith,
                           between Grantor and Beneficiary, only during the
                           first nine years of the Term;

                 (ix)      such notice received under (vii) above shall be
                           accompanied by the payment of Beneficiary of a
                           non-refundable fee in the amount of .25% of the
                           outstanding loan balance in cash or




                                      -48-
<PAGE>   53
                           certified check to be retained by Beneficiary in
                           order to induce Beneficiary to allow the proposed
                           transferee to assume the obligations of Grantor under
                           the loan documents, and such fee shall be returned to
                           Grantor if Beneficiary disapproves of such transfer;

                  (x)      the loan-to-value ratio of the Mortgage based on a
                           then current appraisal obtained at Grantor's expense
                           and acceptable to Beneficiary must not exceed 60%;

                 (xi)      Grantor shall provide Beneficiary with such evidence
                           as Beneficiary may require that such transfer shall
                           not affect or impair Beneficiary's security and
                           rights under the loan documents or under any tenant
                           leases;

                (xii)      Grantor shall pay for all of Beneficiary's costs and
                           expenses associated with the transfer, including
                           without limitation, attorney's fees charged by
                           Beneficiary's staff counsel, special counsel and
                           outside counsel;

               (xiii)      the proposed transferee, in addition to complying
                           with all of the other conditions contained herein,
                           must expressly assume all of the obligations and
                           liabilities of Grantor under the Loan (with the same
                           degree of recourse liability as Grantor and subject
                           to the same exculpatory provisions) that accrue after
                           the effective date of the permitted transfer; and

                (xiv)      Beneficiary receives an opinion of counsel acceptable
                           to Beneficiary and Beneficiary's counsel that
                           contains equivalent opinions to the extent applicable
                           with respect to 




                                      -49-
<PAGE>   54
                           the proposed transferee that were given with respect
                           to Grantor on the Loan Closing Date, that the
                           proposed transferee is duly formed and validly in
                           existence with applicable laws, and the proposed
                           transferee has duly authorized, executed and
                           delivered the agreement by which the transferee
                           assumes the loan pursuant to (xi) above and same is
                           valid and enforceable against the proposed transferee
                           and the Property.

         Notwithstanding the foregoing, no transfer shall be permitted during
any earnout period, or prior to the time any additional collateral, including
without limitation any guarantee, letter of credit, escrowed amounts, master
lease by Grantor, or any other additional collateral posted by Grantor as
security for the Mortgage has been released or collected.

         "Qualified Real Estate Investor" is defined as any reputable
corporation, partnership, joint venture, joint-stock company, trust or
individual with a minimum net worth of $150,000,000, real estate assets of
$100,000,000, a minimum current cash position of $5,000,000, based in the United
States and free from any bankruptcy, reorganization or insolvency proceedings or
any criminal charges or proceedings and shall not have been, at the time of
transfer or in the past, a litigant, plaintiff or defendant in any suit brought
against or by Beneficiary. Beneficiary agrees to be reasonable in the review of
such qualifications.

         "Debt Service Coverage" is defined as the ratio, as determined by
Beneficiary, of (a) Net Operating Income from the Real Property for the
applicable period of time to (b) Total Annual Debt Service. "Net Operating
Income" is defined as gross income from operations of the Real Property for the
previous twelve (12)-month period from leases of space therein, parking
operations, concessions or licenses (to the extent Beneficiary reasonably




                                      -50-
<PAGE>   55
projects such income will continue for the immediately succeeding twelve (12)
month period), subtracting therefrom all necessary and ordinary operating
expenses applicable to the Real Property for such period of time (both fixed and
variable to the extent reasonably projected by Beneficiary to continue for the
next succeeding a twelve (12) month period), including but not limited to,
utilities, administrative, cleaning, landscaping, security, repairs and
maintenance, ground rent payments, management fees, real estate and other taxes,
assessments and insurance, but excluding therefrom deductions for federal, state
and other income taxes, debt service expense, depreciation or amortization of
capital expenditures and other similar noncash items. Gross income shall not be
anticipated for any greater time period than that approved by generally accepted
accounting principles nor shall ordinary operating expenses be prepaid.
Documentation of Net Operating Income shall be certified by an officer of
Grantor with detail satisfactory to Beneficiary and shall be subject to the
approval of Beneficiary. "Total Annual Debt Service" shall mean the sum of (i)
the aggregate debt service payments (including principal and interest) on the
loan for the applicable time period, plus (ii) the aggregate debt service
payments (including principal and interest) on all other indebtedness secured by
a lien on all or part of the Real Property for the applicable time period.

         Cornerstone Properties Inc., a Nevada corporation ("Cornerstone"), is
the parent company of each of the general partners of Grantor. Notwithstanding
the foregoing, the shares of Cornerstone that are publicly traded may be freely
transferred.

         26. Events of Default. Each of the following shall constitute an "Event
of Default" hereunder and shall entitle the Beneficiary to exercise its remedies
hereunder and under any of the other Loan Documents or as otherwise provided by
law:




                                      -51-
<PAGE>   56
                  (a) Any payment of any installment of principal or interest
         due under the Notes, or payment of any escrow deposit under Section 5
         of this Deed of Trust is not received by Beneficiary within five (5)
         business days following the date when such payment was due, or any
         other payment of money or indebtedness as required by this Deed of
         Trust or any other Loan Document is not received when due and remains
         unpaid for thirty (30) days or more after notice of such default by
         Beneficiary to Grantor;

                  (b) Failure of the Grantor in the observance or performance of
         any covenant, promise or agreement provided in this Deed of Trust or in
         any other Loan Document other than relating to the payment of
         indebtedness or money ("failure to perform") for thirty (30) days after
         notice by Beneficiary to Grantor specifying the nature of the failure
         to perform; provided, however, that if the nature of such failure to
         perform is such that the same cannot be cured within such thirty (30)
         day period, such failure to perform shall not be deemed an Event of
         Default if Grantor shall within such period commence to cure that
         failure to perform and thereafter diligently prosecute the cure to
         completion, but in no event more than one hundred eighty (180) days in
         the aggregate. Notwithstanding anything contained herein to the
         contrary, the notice and cure period provided under this clause (b)
         shall not be applicable to and shall not be in addition to any specific
         notice and cure or notice to perform period provided under any other
         provision of this Deed of Trust, and the specific notice and cure or
         notice to perform period provided for in such provision shall control,
         and a failure by Grantor to cure a default or comply by its performance
         under such provision within the applicable cure or performance period
         shall be an Event of Default under this Deed of Trust;




                                      -52-
<PAGE>   57
                  (c) Any representation, warranty, or statement of Grantor or
         the managing general partner of Grantor contained herein or in any of
         the Loan Documents, or in any writing delivered to Beneficiary on or
         before the execution and delivery of the Loan Documents including
         without limitation the Environmental Indemnification Agreement, proves
         to be untrue or inaccurate in any material respect as of the date when
         made and the condition or state of facts rendering such representations
         or warranty untrue or inaccurate is not remedied by Grantor within
         thirty (30) days after notice by Beneficiary to Grantor;


                  (d) Grantor or the managing general partner of Grantor shall
         (i) have an order for relief entered in a proceeding under Title 11,
         United States Code, whether such order shall result from a voluntary or
         involuntary petition, (ii) seek or consent to the appointment of a
         receiver or trustee for itself or for any of the Security, (iii) file a
         petition or initiate a proceeding under the bankruptcy, insolvency,
         receivership, or similar laws of the United States, any state or any
         jurisdiction, (iv) make a general assignment for the benefit of
         creditors, or (v) be unable to pay its debts as they mature;

                  (e) A court shall enter an order, judgment or decree
         appointing, without the consent of Grantor or the managing general
         partner of Grantor, a receiver or trustee for it or for any of the
         Security or approving a petition filed against Grantor which seeks
         relief under the bankruptcy or other similar laws of the United States,
         any state or any jurisdiction, and such order, judgment or decree shall
         remain in force, undischarged or unstayed, sixty (60) days after it is
         entered;

                  (f) Without the prior written consent of the Beneficiary or as
         permitted by this Deed of Trust, (i) the Security or any portion
         thereof, or interest therein, shall be mortgaged, encumbered, sold,


                                      -53-
<PAGE>   58
         assigned or otherwise transferred by the Grantor or by operation of law
         (ii) if the Grantor is a partnership, joint venture, syndicate or other
         group, all or any portion of the interest of any partner or member
         thereof is sold, pledged, assigned or otherwise transferred.

                  (g) Any monetary default (or any nonmonetary default which is
         not cured prior to expiration of any cure period thereunder) under any
         secondary financing approved by Beneficiary in accordance with the
         provisions of Section 10 hereof.

                  (h) Any default occurs under the Ground Lease.

         27. Remedies Upon Default. Immediately upon the occurrence of any Event
of Default, the Trustee and Beneficiary shall have the option, in addition to
and not in lieu of or substitution for all other rights and remedies provided in
this Deed of Trust or any other Loan Document or provided by law or in equity,
and is hereby authorized and empowered by the Grantor, to do any or all of the
following:

                  (a) Declare without notice the entire unpaid amount of the
         Indebtedness, immediately due and payable and, at the Beneficiary's
         option, (i) to bring suit therefor, or (ii) to bring suit for any
         delinquent payment of or upon the Indebtedness, or (iii) to take any
         and all steps and institute any and all other proceedings at law or in
         equity that the Beneficiary deems necessary to enforce payment of the
         Indebtedness and performance of other obligations secured hereunder and
         to protect the lien of this Deed of Trust.

                  (b) Commence foreclosure proceedings against the Security, in
         a single parcel or in several parcels, through a sale by the Trustee or
         by judicial proceedings, by advertisement or as otherwise provided by
         law,


                                      -54-
<PAGE>   59
         at the option of the Beneficiary, pursuant to the statutes in such case
         made and provided, and to sell the Security or to cause the same to be
         sold at public sale, and to convey the same to the purchaser, in
         accordance with said statutes in a single parcel or in several parcels
         at the option of the Beneficiary.

                  (c) Proceed against the Personal Property in accordance with
         Beneficiary's rights and remedies with respect to the Personal
         Property, including the right to sell the Personal Property together
         with the Real Property, separately and without regard to the remainder
         of the Security in accordance with Beneficiary's rights and remedies
         provided by the Colorado Uniform Commercial Code as well as other
         rights and remedies available at law or in equity.

                  (d) Cause to be brought down to date a title examination and
         tax histories of the Security, procure title insurance or title reports
         or, if necessary, procure new abstracts and tax histories.

                  (e) Procure an updated or entirely new environmental audit of
         the Security including building, soil, ground water and subsurface
         investigations; have the Improvements inspected by an engineer or other
         qualified inspector and procure a building inspection report; procure
         an MAI or other appraisal of the Security or any portion thereof; enter
         upon the Security at any time and from time to time to accomplish the
         foregoing and to show the Security to potential purchasers and
         potential bidders at foreclosure sale; make available to potential
         purchasers and potential bidders all information obtained pursuant to
         the foregoing and any other information in the possession of
         Beneficiary regarding the Security.

                  (f) Either by itself or by its agent to be appointed by it for


                                      -55-
<PAGE>   60
         that purpose or by a receiver appointed by a court of competent
         jurisdiction, as a matter of strict right, without notice and without
         regard to the adequacy or value of any security for the Indebtedness or
         the solvency of any party bound for its payment, to take possession of
         and to operate the Security, Grantor hereby waiving any right Grantor
         might have to object to or oppose any such possession and, whether or
         not Beneficiary has taken possession of the Security, to collect and
         apply the Rents, including those past due and unpaid, after payment of
         all necessary charges and expenses, in reduction of the Indebtedness.
         The receiver shall have all of the rights and powers permitted under
         the laws of the State of Colorado. Except for damage caused by
         Beneficiary's willful misconduct, Grantor hereby waives any claim
         Grantor may have against Beneficiary for mismanagement of the Security
         during Beneficiary's operation of the Security under this subparagraph
         or as mortgagee in actual possession under applicable statutes.

                  (g) Beneficiary may, at its option, without waiving any Event
         of Default, pay, perform or observe the same, and all payments made or
         costs or expenses incurred by Beneficiary in connection therewith shall
         be secured hereby and shall be, without demand, immediately repaid by
         Grantor to Beneficiary with interest thereon at the default rate
         provided in the Notes. Beneficiary shall be the sole judge of the
         necessity for any such actions and of the amounts to be paid.
         Beneficiary is hereby empowered to enter and to authorize others to
         enter upon the Security or any part thereof for the purpose of
         performing or observing any such defaulted term, covenant or condition
         without hereby becoming liable to Grantor or any person in possession
         holding under Grantor.

                  (h) Apply against the Indebtedness in such order as
         Beneficiary shall determine any funds held for the benefit of Grantor
         in escrow by


                                      -56-
<PAGE>   61
         Beneficiary or by any third-party escrow agent under any of the Loan
         Documents, including without limitation any funds held under the escrow
         established by Section 5 of this Deed of Trust.

                  (i) Upon any foreclosure sale, Beneficiary may bid for and
         purchase the Security and shall be entitled to apply all or any part of
         the Indebtedness as a credit to the purchase price. In the event of any
         sale of the Security by foreclosure, through judicial proceedings, by
         advertisement or otherwise, the proceeds of any such sale which are
         applied in accordance with this Deed of Trust shall be applied in the
         order following to: (i) all expenses incurred for the collection of the
         Indebtedness and the foreclosure of this Deed of Trust, including
         reasonable compensation to Trustee and Beneficiary, their agents and
         attorneys; (ii) all sums expended or incurred by the Beneficiary and
         Trustee directly or indirectly in carrying out the terms, covenants and
         agreements of the Notes or notes evidencing the Indebtedness, of this
         Deed of Trust and any other Loan Documents, together with interest
         thereon as therein provided; (iii) all late payment charges, prepayment
         fees, advances and other amounts due under any of the Loan Documents;
         (iv) all accrued and unpaid interest upon the Indebtedness; (v) the
         unpaid principal amount of the Indebtedness; and (vi) the surplus, if
         any, to the person or persons legally entitled thereto.

         In the event of any acceleration of the Indebtedness pursuant to the
first paragraph of this Section, Grantor shall pay to Beneficiary together with
the principal indebtedness and interest thereon an amount equal to the
prepayment fee provided for in the Notes and such fee shall be included as part
of the Indebtedness.

         Failure to exercise any option to accelerate in the event of a default
or other circumstance permitting the exercise of such option, shall not


                                      -57-
<PAGE>   62
constitute a waiver of the default or of the right to exercise such option at a
later time, or a waiver of the right to exercise such option in the event of any
other default or circumstance specified above.

         28. Acceleration Interest. In addition to any late payment charge which
may be due under the Notes, Grantor shall pay interest on all sums due hereunder
at a rate (the "Default Rate") equal to the lesser of (i) the interest rate set
forth in the Notes plus four percent (4%) per annum, or (ii) the maximum rate
permitted by law, from and after the first to occur of the following events: if
Beneficiary elects to cause the acceleration of the Indebtedness; if a petition
under Title 11, United States Code, shall be filed by or against Grantor or if
Grantor shall seek or consent to the appointment of a receiver or trustee for
itself or for any of the Security, file a petition seeking relief under the
bankruptcy or other similar laws of the United States, any state or any
jurisdiction, make a general assignment for the benefit of creditors, or be
unable to pay its debts as they become due; if a court shall enter an order,
judgment or decree appointing, with or without the consent of Grantor, a
receiver or trustee for it or for any of the Security or approving a petition
filed against Grantor which seeks relief under the bankruptcy or other similar
laws of the United States, any state or any jurisdiction, and any such order,
judgment or decree shall remain in force, undischarged or unstayed, sixty (60)
days after it is entered; or if all sums due hereunder are not paid on the
Maturity Date as set forth in the Notes.

         29. Late Charge. In the event any payment of principal or interest due
under any of the Notes, or any escrow payment due under Section 5 of this Deed
of Trust, are not paid by Grantor within five (5) business days following the
due date for such payment, Grantor shall pay to Beneficiary a late charge for
the month during which such payment is not made when due, and for each month or
fraction thereof that such sum remains unpaid, equal to the lesser of


                                      -58-
<PAGE>   63
four percent (4%) of such installment or the maximum allowed by law, as the
reasonable estimate by Beneficiary and Grantor of a fair average compensation
for the loss that may be sustained by Beneficiary due to the failure of Grantor
to make timely payments, and such amount shall be secured hereby. Such late
charge shall be paid without prejudice to the right of Beneficiary to collect
any other amounts provided to be paid or to declare an Event of Default under
this Deed of Trust or any other Loan Document.

         30. Waiver Of Statutory Rights. Grantor agrees, to the full extent
permitted by law, that in an Event of Default on the part of Grantor hereunder,
neither Grantor nor anyone claiming through or under Grantor will set up, claim,
or seek to take advantage of any moratorium, reinstatement, forbearance,
appraisement, valuation, stay, homestead, extension, exemption or redemption
laws now or hereafter in force, in order to prevent or hinder the enforcement or
foreclosure of this Deed of Trust, or the sale of the Security, or the delivery
of possession thereof immediately after such sale to the purchaser at such sale,
and Grantor, for itself and all who may at any time claim through or under it,
hereby waives to the full extent that it may lawfully do so, the benefit of all
such laws, and any and all rights to have the assets subject to the security
interest of this Deed of Trust marshaled upon any foreclosure or sale under the
power granted herein.

         31. Security Interest. This Deed of Trust shall, as to any equipment
and other Personal Property covered hereby, be deemed to constitute a security
agreement, and Grantor, as debtor, hereby grants to Beneficiary, as secured
party, a security interest therein pursuant to the Colorado Uniform Commercial
Code. The Grantor agrees, upon request of the Beneficiary, to furnish an
inventory of Personal Property owned by the Grantor and subject to this Deed of
Trust and, upon request by the Beneficiary, to execute any supplements to this
Deed of Trust, any separate security agreement and any financing statements and
continuation statements in order to include specifically said


                                      -59-
<PAGE>   64
inventory of Personal Property or otherwise to perfect the security interest
granted hereby. Upon any Event of Default, the Beneficiary shall have all of the
rights and remedies provided in said Code or otherwise provided by law or by
this Deed of Trust, including but not limited to the right to require the
Grantor to assemble such Personal Property and make it available to the
Beneficiary at a place to be designated by the Beneficiary which is reasonably
convenient to both parties, the right to take possession of such Personal
Property with or without demand and with or without process of law and the right
to sell and dispose of the same and distribute the proceeds according to law.
The parties hereto agree that any requirement of reasonable notice shall be met
if the Beneficiary sends such notice to the Grantor at least five (5) days prior
to the date of sale, disposition or other event giving rise to the required
notice, and that the proceeds of any disposition of any such Personal Property
may be applied by the Beneficiary first to the reasonable expenses in connection
therewith, including reasonable attorneys' fees and legal expenses incurred, and
then to payment of the Indebtedness. With respect to the Personal Property that
has become so attached to the Real Property that an interest therein arises
under the real property law of the State, this Deed of Trust shall also
constitute a financing statement and a fixture filing under the Colorado Uniform
Commercial Code.

         32. Right Of Entry. Beneficiary and Beneficiary's representatives may
at all times and without notice to Grantor enter upon the Security and inspect
the same, or cause it to be inspected by agents, employees, or independent
contractors of Beneficiary, and show the same to others, but Beneficiary shall
not be obligated to make any such entry or inspection.

         33. Estoppel Certificate. Grantor, within fifteen (15) days after
written request from Beneficiary, will furnish a signed statement in writing,
duly acknowledged, of the amount then due or outstanding hereunder and whether
or not any offsets or defenses exist against the Indebtedness, and if so,




                                      -60-
<PAGE>   65
specifying such offsets and defenses. Upon request by Beneficiary, Grantor shall
exercise any right it may have to request an estoppel certificate for any or all
of the tenants on the Security within five (5) days following Beneficiary's
request.

         34. Annual Statements. Grantor shall, within ninety (90) days after the
end of each fiscal year of Grantor, deliver to Beneficiary (a) annual statements
audited and certified by an independent certified public accountant reasonably
satisfactory to Beneficiary and prepared in accordance with generally accepted
accounting principles, showing in detail (l) a balance sheet for the Security as
of the last day of such fiscal year, (2) a statement of earnings from the
Security for such fiscal year showing, among other things, all rents and other
income therefrom and all expenses paid or incurred in connection with the
operation of the Security, (3) a cash flow statement for the Security; and (b) a
statement signed by Grantor listing all leases of space in the Improvements as
of the last day of such fiscal year, the respective areas demised thereunder,
the names of the tenants, the respective expiration dates of the leases, the
respective rentals provided for therein, and such other information as may
reasonably be requested by Beneficiary.

         Notwithstanding anything herein to the contrary, for so long as title
to the Real Property remains with Grantor and there is no uncured default for
which notice is not required, nor any other uncured default for which notice has
been previously given under any of the Loan Documents, then in lieu of the
opinion from certified public accountants, Beneficiary will accept financial
statements containing the information set forth in the preceding paragraph, in
form and substance satisfactory to Beneficiary signed by Grantor's chief
financial officer or authorized general partner.

         If Grantor omits to prepare and deliver promptly any report required by
this Section, Beneficiary may elect, in addition to exercising any remedy for


                                      -61-
<PAGE>   66
an Event of Default as provided for in this Deed of Trust, to make an audit of
all books and records of Grantor and its beneficiaries, including without
limitation their bank accounts, which in any way pertain to the Security, and to
prepare the statement or statements which Grantor failed to procure and deliver.
Such audit shall be made and such statements shall be prepared by an independent
Certified Public Accountant to be selected by Beneficiary. Grantor shall pay all
expenses of the audit and other services, which expenses shall be secured hereby
as part of the Indebtedness and shall be immediately due and payable with
interest thereon at the Default Rate set forth herein.

         Beneficiary shall afford any information received pursuant to this
Section the same degree of confidentiality that Beneficiary affords similar
information proprietary to Beneficiary; provided, however, that Beneficiary does
not in any way warrant or represent that such information received from Grantor
will remain confidential, and, provided further, that Beneficiary shall have the
unconditional right to disclose, as necessary, any such information in the event
Beneficiary sells, transfers, conveys, or assigns the Deed of Trust or any
portion of the Indebtedness.

         35. Rights Cumulative. Each right and remedy of Beneficiary under this
Deed of Trust, the Notes and any other Loan Documents, shall be in addition to
every other right and remedy of Beneficiary and such rights and remedies may be
enforced separately or in any combination.

         36. Subrogation. To the extent that proceeds of the Indebtedness are
used to pay any outstanding lien, charge or encumbrance affecting the Security,
such proceeds have been advanced by Beneficiary at Grantor's request, and
Beneficiary shall be subrogated to all rights, interest and liens owned or held
by any owner or holder of such outstanding liens, charges and encumbrances,
irrespective of whether such liens, charges or encumbrances are released of
record; provided, however, that the terms and provisions hereof


                                      -62-
<PAGE>   67
shall govern the rights and remedies of Beneficiary and shall supersede the
terms, provisions, rights, and remedies under the lien or liens to which
Beneficiary is subrogated hereunder.

         37. No Waiver. Any failure by Beneficiary or Trustee to insist upon the
strict performance by Grantor of any of the terms and provisions hereof shall
not be deemed to be a waiver of any of the terms and provisions hereof, and
Beneficiary, notwithstanding any such failure, shall have the right thereafter
to insist upon the strict performance by Grantor of any and all of the terms and
provisions hereof to be performed by Grantor.

         38. Deed of Trust Extension. The lien hereof shall remain in full force
and effect during any postponement or extension of the time of payment of the
Indebtedness, or of any part thereof, and any number of extensions or
modifications hereof, or any additional notes taken by Beneficiary, shall not
affect the lien hereof or the liability of Grantor or of any subsequent obligor
to pay the Indebtedness unless and until such lien or liability be expressly
released in writing by Beneficiary.

         39. Indemnification. Grantor shall indemnify and hold Beneficiary
harmless from and against all obligations, liabilities, losses, costs, expenses,
fines, penalties or damages (including attorneys' fees) which Beneficiary may
incur by reason of this Deed of Trust or with regard to the Security prior to
the exercise of any remedies under this Deed of Trust. Grantor shall defend
Beneficiary against any claim or litigation involving Beneficiary for the same,
and should Beneficiary incur such obligation, liability, loss, cost, expense,
fine, penalty or damage, then Grantor shall reimburse Beneficiary upon demand.
Any amount owed Beneficiary under this provision shall bear interest at the
Default Rate set forth herein and shall be secured hereby.


                                      -63-
<PAGE>   68
         40. Nonrecourse. Except as specifically provided in this Section 40 and
in Section 15 of the Notes, neither Grantor, Cornerstone, nor any of the general
or limited partners of Grantor nor any of their respective officers, directors,
shareholders, agents, employees or representatives (collectively the "Exculpated
Parties") shall be personally liable for the payment of any sums due hereunder
or the performance of any obligations of Grantor hereunder or under the other
Loan Documents. No judgment for the repayment of the Principal Indebtedness or
interest thereon or any other amount payable pursuant to any of the Loan
Documents, will be enforced against any of the Exculpated Parties personally or
any property of any of the Exculpated Parties other than the Security and any
other security now or hereafter expressly granted under the Loan Documents in
any action to foreclose this Deed of Trust or to otherwise realize upon any
security now or hereafter expressly granted under the Loan Documents or to
collect any amount payable hereunder.
Notwithstanding the foregoing:

                  (a) Nothing herein contained shall be construed as prohibiting
         Beneficiary from exercising any and all remedies which the Loan
         Documents permit, including the right to bring actions or proceedings
         against Grantor, Cornerstone, and other Exculpated Parties and to enter
         a judgment against Grantor, Cornerstone, and other Exculpated Parties,
         so long as the exercise of any remedy does not extend to execution
         against or recovery out of any property of Grantor, Cornerstone, or any
         other Exculpated Party other than the security expressly granted under
         the Loan Documents;

                  (b) Grantor and Cornerstone shall each be fully and personally
         liable for, and the other Exculpated Parties (to the extent the other
         Exculpated Parties would be liable outside of the provisions of this
         paragraph), shall be fully and personally liable for, (i) misapplying
         any condemnation awards or insurance awards attributable to the


                                      -64-
<PAGE>   69
         Security, to the full extent of such awards so misapplied, (ii)
         misapplying any security deposits attributable to the Security, to the
         full extent of such deposits so misapplied, (iii) collecting any rents
         more than thirty (30) days in advance in violation of any covenant
         contained in the Loan Documents, to the full extent of such rents so
         collected in advance, (iv) committing fraud or intentional
         misrepresentation in connection with the operation of the Security or
         the making of the loan evidenced hereby, to the full extent of any
         loss, damage, expense or costs (including reasonable attorneys' fees)
         incurred by Beneficiary resulting from such fraud, misrepresentation or
         waste, (v) failing to pay in order of priority: real estate taxes or
         assessments, (or escrow accounts established therefor), operating and
         maintenance expenses relating to the Real Property, other sums required
         by the Loan Documents, deposits into a required reserve account,
         capital expenditures, management fees, leasing fees and expenses,
         marketing and advertising costs and debt service or other amounts due
         on the Indebtedness, but only to the extent of any gross revenues from
         the Security that were available to pay such expenses but were not so
         used during the period beginning six (6) months prior to either (A)
         Grantor's receipt of notice of default under the loan documents or (B)
         the occurrence of a default under the loan documents that would not
         require notice in order to ripen into an event of default, and
         continuing through the date Beneficiary takes title to the Real
         Property; (vi) the seizure or forfeiture of the Security due to the
         criminal activity by Grantor or Cornerstone, any constituent partner of
         Grantor or Cornerstone, or any of their respective shareholders,
         partners, officers, employees or agents, in the full amount of the loss
         incurred by Beneficiary as a result of such seizure or forfeiture.

                  (c) This paragraph shall impose no limitation on Grantor's,
         Cornerstone's, or any other Exculpated Party's personal liability under


                                      -65-
<PAGE>   70
         and the exercise of any of Beneficiary's rights under any indemnity
         from Grantor, Cornerstone, or any other Exculpated Party to Beneficiary
         including but not limited to, the Environmental Indemnification
         Agreement of even date herewith from Grantor and Cornerstone to Payee
         with regard to the Security except as may be expressly set forth
         therein;

                  (d) This paragraph shall impose no limitation on or prejudice
         to the rights of Beneficiary to proceed against any entity or person
         whatsoever, including Grantor, Cornerstone, and the other Exculpated
         Parties, with respect to the enforcement of any guarantees of the
         Principal Indebtedness or other sums due hereunder or under any of the
         other Loan Documents or any part thereof, any master leases, or any
         similar rights of payment that may be entered into after the date
         hereof, except as may be expressly set forth in any such guarantee.

         41. Attorneys' Fees. Any reference to "attorney fees", "attorneys'
fees", or "attorney's fees" in this document includes but is not limited to both
the fees, charges and costs incurred by Beneficiary or Trustee through
Beneficiary's or Trustee's retention of outside legal counsel and the reasonably
allocable fees, costs and charges for services rendered by Beneficiary's or
Trustee's in-house counsel. Any reference to "attorney fees", "attorneys' fees",
or "attorney's fees, shall also include but not be limited to those attorneys or
legal fees, costs and charges incurred by Beneficiary or Trustee in the
collection of any Indebtedness, the enforcement of any obligations hereunder,
the protection of the Security, the foreclosure of this Deed of Trust and
Security Agreement, the sale of the Security, the defense of actions arising
hereunder and the collection, protection or setoff of any claim the Beneficiary
may have in a proceeding under Title 11, United States Code. Attorneys Fees
provided for hereunder shall accrue whether or not Beneficiary has provided
notice of default or of an intention to exercise


                                      -66-
<PAGE>   71
its remedies for such default.

         42. Administrative Fees. Beneficiary shall have the right to charge
administrative fees during the term of the Notes as Beneficiary may determine,
in its sole reasonable discretion, in connection with any servicing requests
made by Grantor requiring Beneficiary's evaluation, preparation and processing
of any such requests. Administrative fees shall not be charged for routine
servicing matters contemplated by the Loan Documents including, without
limitation: processing payments; processing insurance and UCC continuation
documentation; processing escrow draws; review of tenant leases, subordination
non-disturbance and attornment agreements and tenant estoppels on standard forms
approved by Beneficiary without material modifications. Such administrative fees
shall apply without limitation to requests for matters not permitted or
contemplated by the Loan Documents (including, without limitation: requests for
transfers or assignments, requests for partial releases; requests for review of
new easements), and to requests, which, while contemplated by the Loan
Documents, because of the nature of the request, will require significantly more
time than an institutional lender, acting reasonably, would contemplate for such
request (including without limitation, requests for the approval of tenant
leases, tenant estoppels and tenant subordination, non-disturbance and
attornment agreements which contain material differences from Beneficiary's
standard forms). Beneficiary shall also be entitled to reimbursement for
professional fees it incurs for such administration, including without
limitation, those of architects, engineers and attorneys (whether (i) employed
by Beneficiary or its affiliate or (ii) engaged by Beneficiary or its affiliates
as independent contractors); provided, however, that the three lenders which
comprise Beneficiary shall act together in employing and engaging third parties
and in other matters which would result in administrative fees under this
Section 42 in order to avoid multiple or overlapping fees.


                                      -67-
<PAGE>   72
         43. Trustee's Costs and Expenses; Governmental Charges. Grantor shall
pay all costs, fees and expenses of Trustee, its agents and counsel in
connection with the performance of its duties hereunder, including without
limitation the cost of any trustee's sale guaranty or other title insurance
coverage ordered in connection with any foreclosure proceedings hereunder, and
shall pay all taxes (except federal and state income taxes) or other
governmental charges or impositions imposed by any governmental authority on
Trustee or Beneficiary by reason of their interest in the Loan Documents.

         44. Protection of Security; Costs and Expenses. Grantor shall appear in
and defend any action or proceeding purporting to affect the security hereof or
the rights or powers of the Beneficiary or Trustee, and shall pay all costs and
expenses, including without limitation cost of evidence of title and reasonable
attorneys' fees, in any such action or proceeding in which Beneficiary or
Trustee may appear, and in any suit brought by Beneficiary to foreclose this
Deed of Trust or to enforce or establish any other rights or remedies of
Beneficiary hereunder. If Grantor fails to perform any of the covenants or
agreements contained in this Deed of Trust, or if any action or proceeding is
commenced which affects Beneficiary's or Trustee's interest in the Security or
any part thereof, including, but not limited to, eminent domain, code
enforcement, or proceedings of any nature whatsoever under any federal or state
law, whether now existing or hereafter enacted or amended, relating to
bankruptcy, insolvency, arrangement, reorganization or other form of debtor
relief, or to a decedent, then Beneficiary or Trustee may, but without
obligation to do so and without notice to or demand upon Grantor and without
releasing Grantor from any obligation hereunder, make such appearances, disburse
such sums and take such action as Beneficiary or Trustee deems necessary or
appropriate to protect Beneficiary's or Trustee's interest, including, but not
limited to, disbursement of reasonable attorneys' fees, entry upon the Security
to make repairs or take other action to protect the security hereof, and
payment, purchase, contest or compromise of any



                                      -68-
<PAGE>   73
encumbrance, charge or lien which in the judgment of either Beneficiary or
Trustee appears to be prior or superior hereto. Grantor further agrees to pay
all reasonable expenses of Beneficiary or Trustee (including without limitation
fees and disbursements of counsel) incident to the protection of the rights of
Beneficiary hereunder, or to enforcement or collection of payment of the
Indebtedness, whether by judicial or non-judicial proceedings, or in connection
with any bankruptcy, insolvency, arrangement, reorganization or other debtor
relief proceeding of Grantor, or otherwise. Any amounts disbursed by Beneficiary
or Trustee pursuant to this Section shall be additional indebtedness of Grantor
secured by the Loan Documents as of the date of disbursement and shall bear
interest at the Default Rate. All such amounts shall be payable by Grantor
immediately without demand. Nothing contained in this Section shall be construed
to require Beneficiary or Trustee to incur any expense, make any appearance, or
take any other action.

         45. Notices. Any notice, demand, request, statement or consent made
hereunder shall be in writing, signed by the party giving such notice, request,
demand, statement, or consent, and shall be deemed to have been properly given
when either delivered personally, delivered to a reputable overnight delivery
service providing a receipt or deposited in the United States mail, postage
prepaid and registered or certified return receipt requested, at the address set
forth below, or at such other address within the continental United States of
America as may have theretofore have been designed in writing. The effective
date of any notice given as aforesaid shall be the date of personal service, one
(1) business day after delivery to such overnight delivery service, or three (3)
business days after being deposited in the United States mail, whichever is
applicable. For purposes hereof, the addresses are as follows:

If to Beneficiary:

                  Connecticut General Life Insurance Company


                                      -69-
<PAGE>   74
                  c/o CIGNA Investments, Inc.
                  900 Cottage Grove Road
                  Hartford, CT  06152-2319
                  Attn:  Investment Services, S-319

                  American General Realty Advisors, Inc.
                  2929 Allen Pkwy., 34th Floor
                  Houston, TX 77019
                  Attn: Director, Mortgage Loans

         And
                  Massachusetts Mutual Life Insurance Company
                  1295 State Street
                  Springfield, MA 01111
                  Attn:  ITS: Senior Managing Director of Real Estate

with a copy to:

                  CIGNA Corporation
                  Investment Law Department
                  900 Cottage Grove Road
                  Hartford, CT  06152-2215
                  Attn:  Real Estate Division, S-215A

with a courtesy copy to:

                  Fairfield and Woods, P.C.
                  1700 Lincoln Street, Suite 2400
                  Denver, CO 80203
                  Attn: Thomas P. Kearns, Esq.

If to Grantor:

                  c/o Cornerstone Properties Inc.
                  126 East 56th Street
                  New York, New York 10022
                  Attn: Kevin Mahoney

with a courtesy copy to:

                  Sherman & Sterling
                  Citicorp Center
                  153 East 53rd Street
                  New York City, N.Y. 10022-4676
                  Attn: Timothy G. Little, Esq.


                                      -70-
<PAGE>   75
         Notwithstanding the foregoing agreement to provide a courtesy copy to
Grantor's attorneys, such copy shall be a courtesy copy only, and failure to
provide such courtesy copy shall have absolutely no effect or entitle Grantor to
any remedy whatsoever. Any notice duly given to Grantor shall be effective
whether or not the courtesy copy was given to Grantor's attorneys.

         46. Release. Upon payment of all sums secured by this Deed of Trust,
Beneficiary shall cause Trustee to release this Deed of Trust and shall produce
for Trustee the Notes. Grantor shall pay all costs of recordation and shall pay
the statutory Trustee's fees.

         47. Applicable Law. The provisions hereof shall be construed in
accordance with the laws of the State of Colorado (the "State").

         48. Intentionally Omitted.

         49. Invalidity. If any provision of this Deed of Trust shall be held
invalid or unenforceable, the same shall not affect in any respect whatsoever
the validity of the remainder of this Deed of Trust, except that if such
provision relates to the payment of a monetary sum, then the Beneficiary may, at
its option, declare the Indebtedness due and payable upon sixty (60) days prior
written notice to Grantor and, provided there exists no Event of Default
hereunder, without prepayment fee or premium.

         50. Captions. The captions in this instrument are inserted only as a
matter of convenience and for reference, and are not and shall not be deemed to
be any part hereof.

         51. Modifications. This Deed of Trust may not be changed or terminated
except in writing by both parties. The provisions of this Deed of Trust shall
extend and be applicable to all renewals, amendments, extensions,


                                      -71-
<PAGE>   76
consolidations, and modifications, of the other Loan Documents, and any and all
references herein to the Loan Documents shall be deemed to include any such
renewals, extensions, amendments, consolidations, or modifications thereof.

         52. Bind and Inure. The provisions of this Deed of Trust shall be
binding on the Grantor and its heirs, successors and assigns, and any subsequent
owners of the Security. The covenants of Grantor herein shall run with the land,
and this Deed of Trust and all of the covenants herein contained shall inure to
the benefit of the Beneficiary, its successors and assigns.

         53. Replacement of Notes. Upon receipt of evidence reasonably
satisfactory to Grantor of the loss, theft, destruction or mutilation of the
Notes, and in the case of any such loss, theft or destruction, upon delivery of
an indemnity agreement reasonably satisfactory to Grantor or, in the case of any
such mutilation, upon surrender and cancellation of the Notes, Grantor will
execute and deliver, in lieu thereof, a replacement Notes, identical in form and
substance to the Notes and dated as of the date of the Notes and upon such
execution and delivery all references in this Deed of Trust to the Notes shall
be deemed to refer to such replacement Notes.

         54. Time of the Essence. Time is of the essence with respect to each
and every covenant, agreement and obligation of Grantor under this Deed of
Trust, the Notes and any of the other Loan Documents.

         55. Approvals and Consents. Except as otherwise hereinafter set forth,
AG, Mass Mutual and CGLIC hereby designate CGLIC to act for and on behalf of AG,
Mass Mutual and CGLIC with respect to all actions required or permitted to be
taken by them, as Beneficiary hereunder or under any of the other Loan Documents
(hereinafter referred to as an "Action"), including but


                                      -72-
<PAGE>   77
not limited to, the right to respond to Grantor with respect to any Action, and
Grantor shall have the right to rely on any such communication; provided,
however, (i) all notices, requests and other communications to Beneficiary shall
be delivered to each of AG, Mass Mutual and CGLIC as set forth in Section 48
hereof, and (ii) AG, Mass Mutual and CGLIC may, at any time, change such
designee or terminate such designation by written notice thereof to Grantor
executed by AG, Mass Mutual and CGLIC. Notwithstanding the foregoing, each of
AG, Mass Mutual and CGLIC, or their respective successors or assigns, shall have
the right to receive all payments on their respective Notes, and neither this
Deed of Trust, the Notes or any of the other Loan Documents shall be modified,
amended or terminated without the joinder of AG, Mass Mutual and CGLIC.


         IN WITNESS WHEREOF, the Grantor has duly executed this Deed of Trust as
of the date first above written, in the presence of:

                                  GRANTOR:

                                  1700 LINCOLN LIMITED

                                  By:   ARICO-Denver, Inc., general partner


                                        By: ________________________________
                                            Name: Kevin P. Mahoney
                                            Title: Vice President


                                        By: ________________________________
                                            Name: Scott M. Dalrymple
                                            Title: Vice President

                                  By:   1700 Lincoln, Inc., general partner


                                        By: ________________________________

                                      -73-
<PAGE>   78

                                            Name: Kevin P. Mahoney
                                            Title: Vice President


                                        By: __________________________________
                                            Name: Scott M. Dalrymple
                                            Title: Vice President


         The undersigned, Cornerstone Properties Inc., hereby executes this Deed
of Trust and Security Agreement for the purpose of acknowledging its Agreement
to accept liability as set forth in Section 40 hereof.



                                        CORNERSTONE PROPERTIES INC.



                                        By: __________________________________
                                            Name: K.P. Mahoney, S.M. Dalrymple
                                            Title: Vice Presidents


                                      -74-
<PAGE>   79
STATE OF __________        )
                           ) ss.
COUNTY OF _________        )

         The foregoing instrument was acknowledged before me this ____ day of
July, 1996, by ___________________ as ____________________ of ARICO-Denver,
Inc., general partner of 1700 Lincoln Limited, a Colorado limited partnership.

         WITNESS my hand and official seal.

         My commission expires:


                                             __________________________________
                                             Notary Public

                                             Address:

                                             __________________________________

                                             __________________________________





STATE OF_________          )
                           ) ss.
COUNTY OF _____________    )


         The foregoing instrument was acknowledged before me this ____ day of
July, 1996, by ___________________ as ____________________ of ARICO-Denver,
Inc., general partner of 1700 Lincoln Limited, a Colorado limited partnership.

         WITNESS my hand and official seal.

         My commission expires:


                                             __________________________________
                                             Notary Public

                                             Address:

                                             __________________________________

                                             __________________________________




                                      -75-
<PAGE>   80
STATE OF ________           )
                            ) ss.
COUNTY OF _____________     )

         The foregoing instrument was acknowledged before me this ____ day of
July, 1996, by ___________________ as ____________________ of 1700 Lincoln,
Inc., general partner of 1700 Lincoln Limited, a Colorado limited partnership.

         WITNESS my hand and official seal.

         My commission expires:

                                             __________________________________
                                             Notary Public

                                             Address:

                                             __________________________________

                                             __________________________________





STATE OF_________           )
                            ) ss.
COUNTY OF _____________     )

         The foregoing instrument was acknowledged before me this ____ day of
July, 1996, by ___________________ as ____________________ of 1700 Lincoln,
Inc., general partner of 1700 Lincoln Limited, a Colorado limited partnership.

         WITNESS my hand and official seal.

         My commission expires:


                                             __________________________________
                                             Notary Public

                                             Address:

                                             __________________________________

                                             __________________________________



                                      -76-
<PAGE>   81

STATE OF_________          )
                           ) ss.
COUNTY OF _____________    )


         The foregoing instrument was acknowledged before me this ____ day of
July, 1996, by ___________________ as ____________________ of Cornerstone
Properties Inc., a Colorado corporation.

         WITNESS my hand and official seal.

         My commission expires:



                                             __________________________________
                                             Notary Public

                                             Address:

                                             __________________________________

                                             __________________________________


                                      -77-
<PAGE>   82
                      DEED OF TRUST AND SECURITY AGREEMENT

                          EXHIBIT A - LEGAL DESCRIPTION

Parcel A: (Highrise building site)

Lots 16 to 20 , inclusive Block 30, H.C. Brown's Addition to Denver, Colorado,
and the West one half of vacated alley lying East of and adjoining said lots

And

Lots 20 to 30, inclusive, Block 30, H.C. Brown's Addition to Denver, Colorado,
and the East one half of vacated alley lying West of and adjoining said lots

And

That portion of Lot 31, Block 30, H.C. Brown's Addition to Denver, Colorado, and
the vacated alley adjoining said lot, described as follows: Beginning at a point
on the South line of said Lot 31, from which the Southeast corner of said Lot 31
lies 101.83 feet Easterly; thence Northerly on a deflection angle of 89 degrees
52'00", and parallel to the East line of said Lot 31, a distance of 0.06 feet;
thence on a deflection angle to the right of 19 degrees 00'00", a distance of
4.25 feet to a point on the outside face on existing circular building
structure; thence Northwesterly along the face of said building structure on a
curve to the right, the chord of which deflects from the last mentioned course
at an angle of 83 degrees 31'27" to the left and the radius of which measures
49.00 feet, an arc length of 8.76 feet to a point of non-tangency, said point
also being on the face of said building structure; thence continuing along said
building face on a deflection angle to the left from the aforementioned chord 25
degrees 28'33", a distance of 24.65 feet to the center of the vacated 16.00 foot
alley adjacent to the West line of said Lot 31;


                                      -78-
<PAGE>   83
thence on a deflection angle to the left of 90 degrees 00'00", and along the
centerline of said vacated 16.00 foot alley, a distance of 7.77 feet to the
point of intersection with the South line of said Lot 31 extended westerly;
thence on a deflection angle to the left of 89 degrees 52'00", a distance of
31.17 feet to the true point of beginning.



                                      -79-
<PAGE>   84
Parcel B: (Parking garage site)

The South one half of Lot 10 and all of Lots 11 to 20, inclusive, Block 35, H.C.
Brown's Addition to Denver, Colorado, together with all of the Southerly 238.29
feet of the vacated alley adjacent thereto, Block 35, H.C. Brown's Addition to
Denver, Colorado, as vacated by ordinance No. 244, Series of 1981, recorded may
15, 1981 in Book 2375 at Page 460; Except the following parcel described in the
Deed from the Lincoln Building Corporation to the City and County of Denver,
recorded July 20, 1981 in Book 2415 at Page 159; A part of Lots 10 and 11 of
Block 35, H.C. Brown's Addition to Denver, City and County of Denver, State of
Colorado, being more particularly described as follows:

Beginning at a point on the West line of said Block 35, 247.35 feet North of the
Southwest corner of said Block 35; thence continuing Northerly along said West
line a distance of 16.00 feet to a point being on the centerline of said Lot 10;
thence on an interior angle left of 89 degrees 52'53" along said centerline of
said Lot 10, a distance of 125.08 feet to a point on the West line of the
existing 16 foot alley; thence on an interior angle left of 90 degrees 07'05"
along the West line of said alley a distance of 25.00 feet; thence on an
interior angle left of 89 degrees 52'55" a distance of 45.00 feet; thence on an
exterior angle right of 212 degrees 42'02" a distance of 16.66 feet; thence on
an exterior angle right of 147 degrees 17'58" a distance of 66.08 feet to the
point of beginning. City and County of Denver, State of Colorado



                                      -80-
<PAGE>   85
TOGETHER WITH THOSE BENEFICIAL INTERESTS DESCRIBED AS FOLLOWS:


BENEFICIAL INTEREST NO. 1: (Underground tunnel - Sherman Street)

Beneficial interest appurtenant to Parcels A and B herein described, as set
forth in the revocable license or permit for underground tunnel in Sherman
Street, a public street, granted by ordinance No. 613, council Bill No. 668,
Series 1980, as recorded February 9, 1981 in Book 2322 at Page 176 of the
records of the City and County of Denver described as follows:

That part of Sherman Street being 18.00 feet in width and lying 9.00 feet on
each side of the centerline described as follows:

Beginning at a point on the East line of Block 30, H.C. Brown's Addition to
Denver, Colorado, said point being a distance of 125.12 feet North of the
Southeast corner thereof; thence Easterly perpendicular to said East line, a
distance of 90.00 feet to a point on the West line of Block 35, H.C. Brown's
Addition to Denver, Colorado and a point of terminus. City and County of Denver,
State of Colorado

BENEFICIAL INTEREST NO. 2: (Transformer vault - Sherman Street)

Beneficial interest appurtenant to Lots 21 to 25 of Block 30 of Parcel A herein
described, as set forth in the revocable license or permit to encroach with
transformer vault in Sherman Street, a public street, granted by Ordinance No.
612, Council Bill


                                      -81-
<PAGE>   86
No. 667, Series 1980, as recorded February 9, 1981 in Book 2322 at Page 178 of
the records of the City and County of Denver described as follows:

Beginning at a point on the East line of Block 30, H.C. Brown's Addition to
Denver, Colorado, said point being a distance of 1.58 feet North of the
Southeast corner thereof; thence Easterly and parallel with the South line of
said Block 30 extended Easterly, a distance of 18.25 feet; thence Northerly and
parallel with the East line of said Block 30, a distance of 114.54 feet; thence
Westerly and parallel with the South line of said Block 30 extended Easterly, a
distance of 18.25 feet to a point on the East line of said Block 30; thence
Southerly along said East line, a distance of 114.54 feet to the point of
beginning. City and County of Denver, State of Colorado


BENEFICIAL INTEREST NO. 3: (Cassions - Sherman Street)

Beneficial interest appurtenant to Parcel A herein described, as set forth in
the revocable license or permit to encroach with caissons in Sherman Street, a
public street, granted by Ordinance No. 528, Council Bill No. 581, Series 1980
as recorded February 9, 1981 in Book 2322 at Page 174 of the records of the City
and County of Denver described as follows:

That part of Sherman Street described as follows: Beginning at a point on the
East line of Block 30, H.C. Brown's Addition to Denver, Colorado, said point
being 135.85 feet North of the Southeast corner of said Block 30; thence
Easterly and parallel with the South line of said Block 30 extended Easterly 1


                                      -82-
<PAGE>   87
foot; thence Northerly and parallel with the East line of said Block 30, 95.67
feet; thence Westerly and parallel with the South line of said Block 30 extended
Easterly 1 foot to a point on the East line of said Block 30;

thence Southerly along said East line to the point of beginning. City and County
of Denver, State of Colorado


BENEFICIAL INTEREST NO. 4: (Overhead pedestrian bridge - Lincoln Street)

Beneficial interest appurtenant to Parcel A herein described, as set forth in
the revocable license or permit to encroach with an overhead bridge across
Lincoln Street, a public street, granted by ordinance No. 611, Council Bill No.
666, Series 1980, as recorded February 9, 1981 in Book 2322 at Page 180 of the
records of the City and County of Denver described as follows:

That part of Lincoln Street being 16.66 feet in width and lying 8.33 feet on
each side of the centerline described as follows:

Beginning at a point on the West line of Block 30, H.C. Brown's Addition to
Denver, Colorado, said point being 86.91 feet North of the Southwest corner
thereof; thence Westerly perpendicular to the said West line, a distance of
90.00 feet to a point on the East line of Block 3, H.C. Brown's Addition to
Denver, Colorado and a point of terminus. City and County of Denver, State of
Colorado


BENEFICIAL INTEREST NO. 5: (Principal bank property)

Those certain beneficial interests granted by Lincoln Building Corporation, a
Colorado


                                      -83-
<PAGE>   88
corporation and by United Bank of Denver National Association, to 1700 Lincoln
Limited, a Colorado limited partnership, in instrument entitled Reciprocal
Easement Grant and Agreement recorded February 9, 1981 in Book 2322 at Page 323
of the records of the City and County of Denver, State of Colorado.






                                      -84-
<PAGE>   89
                      DEED OF TRUST AND SECURITY AGREEMENT


   Exhibit B - Form of Subordination, Nondisturbance and Attornment Agreement



Tenant Name:   _______________________________
Trade Name:    _______________________________
Room/Unit No.: _______________________________


         THIS AGREEMENT is dated the _____ day of ____________________, 19__,
and is made by and among CONNECTICUT GENERAL LIFE INSURANCE COMPANY, having an
address of c/o CIGNA Investments, Inc., 900 Cottage Grove Road, Bloomfield,
Connecticut 06002, Attn: Real Estate Investment Services S-319; AMERICAN GENERAL
LIFE INSURANCE COMPANY, having an address of c/o American General Realty
Advisors, Inc., 2929 Allen Pkwy., 34th Floor, Houston, TX 77019; and
MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY, having an address of 1295 State
Street, Springfield, MA 01111 (collectively "Mortgagee"), _____________________
_________________________, d/b/a __________________________________________,
having an address of __________________________________________________________
("Tenant"), and _______________________________, having an address of _________
__________________________ ("Landlord).

                                    RECITALS:

         A. Tenant has entered into a lease ("Lease") dated _________________,
19___ with ____________________ as lessor ("Landlord"), covering the premises
known as ____________________ (the "Premises") within the property known as
____________________, more particularly described as shown on Exhibit A,
attached hereto (the "Real Property").

         B. Mortgagee has agreed to make or has made a mortgage loan in the
amount of ____________________ to Landlord, secured by a mortgage of the Real
Property (the "Mortgage"), and the parties desire to set forth their agreement
herein.

         NOW, THEREFORE, in consideration of the premises and other valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereby agree as follows:

         1. The Lease and all extensions, renewals, replacements or
modifications thereof are and shall be subject and subordinate to the Mortgage
and all terms and conditions thereof insofar as it affects the Real Property of
which the Premises form a part, and to all renewals, modifications,
consolidations, replacements and extensions thereof, to the full extent of
amounts secured thereby and interest thereon.

         2. Tenant shall attorn to and recognize any purchaser at a foreclosure
sale under the Mortgage, any transferee who acquires the Premises by deed in
lieu of foreclosure, and the successors and assigns of such purchaser(s), as its
landlord for the unexpired balance (and any extensions, if exercised) of the
term of the Lease on the same terms and conditions set forth in the Lease.

         3. If it becomes necessary to foreclose the Mortgage, Mortgagee shall


                                      -85-
<PAGE>   90
neither terminate the Lease nor join Tenant in summary or foreclosure
proceedings so long as Tenant is not in default under any of the terms,
covenants, or conditions of the Lease.

         4. If Mortgagee succeeds to the interest of Landlord under the Lease,
Mortgagee shall not be:

             a. liable for any act or omission of any prior landlord (including
         Landlord);

             b. liable for the return of any security deposit unless such
         deposit has been delivered to Mortgagee by Landlord or is in an escrow
         fund available to Mortgagee;

             c. subject to any offsets or defenses that Tenant might have
         against any prior landlord (including Landlord);

             d. bound by any rent or additional rent that Tenant might have paid
         for more than the current month to any prior landlord (including
         Landlord);

             e. bound by any amendment, modification, or termination of the
         Lease made without Mortgagee's consent;

             f. personally liable under the Lease, Mortgagee's liability
         thereunder being limited to its interest in the Real Property; or

             g. bound by any notice of termination given by Landlord to Tenant
         without Mortgagee's prior written consent thereto.

         5. This Agreement shall be binding on and shall inure to the benefit of
the parties hereto and their successors and assigns.

         6. Tenant shall give Mortgagee, by certified mail, return receipt
requested, or by commercial overnight delivery service, a copy of any notice of
default served on Landlord, at Mortgagee's address set forth above or at such
other address as to which Tenant has been notified in writing. If Landlord shall
have failed to cure such default within the time provided for in the Lease, then
Mortgagee shall have an additional ten (10) days within which to cure any
default capable of being cured by the payment of money and an additional thirty
(30) days within which to cure any other default or if such default cannot be
cured within that time, then such additional time as may be necessary to cure
such default shall be granted if within such thirty (30) days Mortgagee has
commenced and is diligently pursuing the remedies necessary to cure such default
(including, but not limited to, commencement of foreclosure proceedings, if
necessary to effect such cure), in which event the Lease shall not be terminated
while such remedies are being so diligently pursued.

         7. Landlord has agreed under the Mortgage and other loan documents that
rentals payable under the Lease shall be paid directly by Tenant to Mortgagee
upon default by Landlord under the Mortgage. After receipt of notice from
Mortgagee to Tenant, at the address set forth above or at such other address as
to which Mortgagee has been notified in writing, that rentals under the


                                      -86-
<PAGE>   91
Lease should be paid to Mortgagee, Tenant shall pay to Mortgagee, or at the
direction of Mortgagee, all monies due or to become due to Landlord under the
Lease. Tenant shall have no responsibility to ascertain whether such demand by
Mortgagee is permitted under the Mortgage, or to inquire into the existence of a
default. Landlord hereby waives any right, claim, or demand it may now or
hereafter have against Tenant by reason of such payment to Mortgagee, and any
such payment shall discharge the obligations of Tenant to make such payment to
Landlord.

         8. Tenant declares, agrees and acknowledges that Mortgagee, in making
disbursements pursuant to any agreement relating to the Loan, is under no
obligation or duty to, nor has Mortgagee represented that it will, see to the
application of such proceeds by the person or persons to whom Mortgagee
disburses such proceeds, and any application or use of such proceeds for
purposes other than those provided for in such agreement shall not defeat the
subordination herein made in whole or in part.

            IN WITNESS WHEREOF, the parties hereto have executed these presents\
as of the day and year first above written.

Mortgagee: CONNECTICUT GENERAL LIFE INSURANCE COMPANY



By: ________________________               By: ________________________
Its:________________________               Its:________________________
Date:_______________________               Date:_______________________

Mortgagee: AMERICAN GENERAL LIFE INSURANCE COMPANY



By: ________________________               By: ________________________
Its:________________________               Its:________________________
Date:_______________________               Date:_______________________


Mortgagee: MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY



By: ________________________               By: ________________________
Its:________________________               Its:________________________
Date:_______________________               Date:_______________________



Tenant: ____________________


By: ________________________               By: ________________________
Its:________________________               Its:________________________
Date:_______________________               Date:_______________________


Landlord: __________________



                                      -87-
<PAGE>   92
By: ________________________               By: ________________________
Its:________________________               Its:________________________
Date:_______________________               Date:_______________________



                                      -88-
<PAGE>   93
                                  [CORPORATION]


[STATE OR COMMONWEALTH OF __________________]    )
                                                 )ss.
[COUNTY OF _________________]                    )


         On this, the ______ day of ___________________, before me, notary
public, the undersigned officer, personally appears _____________________, who
acknowledged himself to be the _______________________ of
________________________, a corporation, and the foregoing instrument for the
purposes therein contained, by signing the name of the corporation by himself as
such officer.

         IN WITNESS WHEREOF, I hereunto set my hand and official seal the day
and year aforesaid.


                                             __________________________________
                                             Notary Public


My Commission Expires:



                                  [PARTNERSHIP]

STATE OF  ___________    )
                         ) ss.
COUNTY OF ___________    )


         On this _________ day of _________________________ in the year _______
before me, _______________________, a Notary Public of said State, duly
commissioned and sworn, personally appeared _______________, known to me (or
proved to me on the oath of _____________________) to be a general partner of a
limited partnership that executed the within instrument, and acknowledged to me
that such partnership executed the same.


                                             __________________________________
                                             Notary Public



                                      -89-
<PAGE>   94
[CII ON BEHALF OF CGLIC]


STATE OF CONNECTICUT  )
                      ) SS.
COUNTY OF HARTFORD    )


         On this __________ day of ____________________, 1996, personally
appeared __________________ who acknowledged himself to be the
______________________ and ______________________________ who acknowledged
himself to be the _______________________ of CIGNA Investments, Inc., a
corporation, duly authorized to sign on behalf of Connecticut General Life
Insurance Company, a corporation, and that each of them, being authorized so to
do, executed the foregoing instrument for the purposes therein contained by
signing the name of the corporation.

         IN WITNESS WHEREOF, I hereunto set my hand.


                                             __________________________________
                                             Notary Public
                                             My Commission Expires:



STATE OF TEXAS      )
                    ) ss.
COUNTY OF HARRIS    )


         The foregoing instrument was acknowledged before me this ______ day of
_________, 1996, by ______________________ as Real Estate Investment Officer and
_______________________________ as Assistant Secretary of American General Life
Insurance Company, a Texas corporation.

WITNESS MY HAND AND SEAL


____________________________
Notary Public
My Commission Expires:




                                      -90-
<PAGE>   95
                                    EXHIBIT A

                                   (SNDA-MTG)


                             Description of Premises







                                      -91-
<PAGE>   96
                                                                Denver, Colorado



                                 PROMISSORY NOTE
                  (MASSACHUSETTS MUTUAL LIFE INSURANCE COMPANY)


$32,666,667                                                        July 23, 1996



      FOR VALUE RECEIVED, 1700 Lincoln Limited (hereinafter referred to as
"Maker"), promises to pay to the order of Massachusetts Mutual Life Insurance
Company, a Massachusetts corporation, having its principal office at 1295 State
Street, Springfield, Massachusetts 01111 (the "Payee"), or such other place as
the Holder hereof may designate in writing (the legal holder from time to time
of this Note, including Payee as the initial holder, hereinafter referred to as
"Holder"), the principal sum of THIRTY-TWO MILLION SIX HUNDRED SIXTY-SIX
THOUSAND SIX HUNDRED SIXTY-SEVEN AND NO/100 DOLLARS ($32,666,667), or so much
thereof as may be advanced to or for the benefit of Maker by Holder (hereinafter
referred to as "Principal Indebtedness"), together with interest thereon at an
annual rate of seven and one-half percent (7.5%) (the "Interest Rate"), in
accordance with the provisions hereinafter set forth.

      1. Terms of Payment. If the date on which Principal Indebtedness is
advanced to Maker ("the Advancement Date") is not the first day of a calendar
month, then Maker shall pay to Holder on the first day of the first calendar
month following the Advancement Date, interest only on the Principal
Indebtedness, at the Interest Rate, calculated on the basis of a 365-day year
and the number of days from and including the Advancement Date to and including
the last day of the calendar month in which the Advancement Date occurs. On the
first day of the second calendar month following the Advancement Date (or on the
first day of the first calendar month following the date of this Note, if the
date of this Note is the first day of a calendar month), and on the first day of
each calendar month thereafter (hereinafter called the "monthly payment dates")
until July 1, 2001, Maker shall pay to Holder the sum of $228,410.07
(hereinafter referred to as "monthly payments"), to be applied first to interest
on the Principal Indebtedness from time to time outstanding at the Interest Rate
and the balance to be applied in reduction of the Principal Indebtedness. The
interest component of the monthly payments shall be calculated and applied on
the basis of a 360-day year consisting of twelve 30-day months. On August 1,
2001 (the "Maturity
<PAGE>   97
Date"), subject to extension in accordance with that certain Extension Option
Agreement of even date herewith between Maker and Holder, Maker shall pay to
Holder the entire Principal Indebtedness then remaining unpaid, together with
accrued and unpaid interest thereon at the Interest Rate and any other charges
due under this Note, the Deed of Trust (hereinafter defined), and any other
documents evidencing or securing or pertaining to the advancement or
disbursement of the Principal Indebtedness (collectively, the "Loan Documents").
The period from and including the date hereof to the Maturity Date, as the same
may be extended, will be referred to hereinafter as the "Term".

      2. Prepayment. The term "Loan Years" shall mean the consecutive 12-month
periods measured from the first day of the calendar month following the date of
this Note or, if the date of this Note is the first day of a calendar month,
then measured from the date of this Note. Except as specifically provided herein
or in the Deed of Trust, no prepayment of the Principal Indebtedness shall be
allowed during the first two (2) Loan Years (the "Closed Period"). Maker,
whether or not a debtor in a proceeding under Title 11, United States Code, may
prepay the Principal Indebtedness in full, but not in part, on any monthly
payment date after the Closed Period, provided Maker gives Holder forty-five
(45) days' prior written notice and pays a prepayment fee as described below.

      After the Closed Period the prepayment fee shall be calculated as follows:

            (a)   Through the end of the fourth Loan Year, or, if the Term is
                  extended as provided in that certain Extension Option
                  Agreement of even date herewith between Maker and Holder,
                  through the end of the ninth Loan Year, the greater of:

                  (i)   one percent (1%) of the then-existing balance of this
                        Note, or

                  (ii)  Yield Maintenance as defined below.


                                      -2-
<PAGE>   98
            (b)   For the first nine (9) months of the fifth Loan Year,
                  excluding any period after the Extension Notice, if any, and,
                  for the first nine months of the tenth Loan Year, if
                  applicable, Yield Maintenance as defined below.

      The loan may be prepaid at par during the last three (3) months of the
Term, as the Term may be extended pursuant to the Extension Option Agreement
(the "Open Period"). The foregoing prepayment fee will be due when the loan is
prepaid after the Closed Period and prior to the Open Period, whether such
prepayment is voluntary or results from default, acceleration or any other
cause. Such prepayment fee will not be payable if such prepayment results from a
casualty or condemnation and the application of insurance proceeds or
condemnation awards to the loan.

      In the event of a prepayment during the Closed Period resulting from an
acceleration by reason of Maker's default or any other reason, Maker shall pay
to Holder a default prepayment fee calculated as follows:

            (a)   3% of the then-existing principal balance of this Note, plus

            (b)   Yield Maintenance as defined below:

      Yield Maintenance: Yield Maintenance is defined as the sum of the present
values on the date of prepayment of each Monthly Interest Shortfall for the
remaining Term of the loan discounted to present value at one-twelfth of the sum
of the monthly Treasury Yield plus 50 basis points.

      The Monthly Interest Shortfall is calculated for each monthly payment and
is the product of (i) the positive difference, if any, of the Semi-Annual
Equivalent Rate less an amount equal to the Treasury Yield plus 50 basis points,
divided by 12, times (ii) the principal balance of the loan that would have been
outstanding on each monthly payment date for which the calculation is made for
each full and partial month remaining in the Term, assuming that the loan had
not been prepaid, that all payments due on the Loan had been made


                                      -3-
<PAGE>   99
on their respective due dates and that all such assumed payments had been
applied first to accrued interest and then to principal.

      The present value for each Monthly Interest Shortfall amount is then
determined by discounting each Monthly Interest Shortfall to the present value
as of the date of prepayment of the Loan at one-twelfth the sum of the Treasury
Yield plus 50 basis points.

      The "Semi-Annual Equivalent Rate" for this loan is 7.62%.

      The "Treasury Yield" will be determined by reference to the Federal
Reserve Statistical Release H.15 (519) of Selected Interest Rates (or any
similar successor publication of the Federal Reserve) for the first week ending
not less than two full weeks prior to the prepayment date. If the remaining Term
is less than one year, the Treasury Yield will equal the yield for 1-Year
Treasury Constant Maturities. If the remaining Term is equal to one of the
maturities of the Treasury Constant Maturities (e.g., 1-year, 2-year, etc.),
then the Treasury Yield will equal the yield for the Treasury Constant Maturity
with a maturity equaling the remaining Term. If the remaining Term is longer
than one year, but does not equal one of the maturities of the Treasury Constant
Maturities, then the Treasury Yield will be interpolated on a straight-line
basis based on the Yields for the Treasury Constant Maturities with a maturity
closest to the remaining Term.

      The aforementioned prepayment fee does not constitute a penalty, but
rather represents the reasonable estimate, agreed to between Maker and Payee, of
a fair compensation for the loss that may be sustained by Holder due to
prepayment of the Principal Indebtedness prior to the Maturity Date. Any
prepayment fee required pursuant to the preceding paragraphs shall be paid
without prejudice to the right of Holder to collect any of the amounts owing
under this Note or the Deed of Trust or otherwise, to enforce any of its rights
or remedies arising out of an Event of Default hereunder.

      3. Security. This Note is secured by, among other things, a deed of trust
(hereinafter referred to as the "Deed of Trust") given by Maker for the


                                      -4-
<PAGE>   100
benefit of Payee and others, of even date herewith, constituting a first lien on
real estate and a first priority security interest in personal property and any
leasehold in such personal property and an assignment of rents and leases
(hereinafter collectively referred to as the "Security"), in the City and County
of Denver, State of Colorado.

      4. Location and Medium of Payments. The sums payable under this Note or
under the Deed of Trust shall be paid to Holder at its principal address
hereinabove set forth, or at such other place as Holder may from time to time
hereafter designate to Maker in writing, in legal tender of the United States of
America.

      5. Acceleration of Maturity. At the option of Holder, which may be
exercised at any time after one or more of the following events (each being an
"Event of Default") shall have occurred, the whole of the Principal
Indebtedness, together with all interest and other charges due under any of the
Loan Documents, shall immediately become due and payable ("Acceleration of
Maturity"): (a) if any payment of any installment of the Principal Indebtedness,
and/or interest or of any other sum due hereunder is not received by Holder
within five business days following the date when such payment was due; or (b)
if a default or an Event of Default shall occur under the Deed of Trust or any
other of the Loan Documents, which is not cured within any applicable grace
period afforded therein, if any.

      6. Late Charges; Interest Following Event of Default. If any payment of
principal or interest due under this Note or any escrow payment required under
Section 5 of the Deed of Trust is not paid when due, without regard to any cure
or grace period, Maker shall pay and Holder shall be entitled to collect a late
payment charge for each month or fraction thereof during which such payment is
not made when due and for each month thereafter that such sum remains unpaid,
equal to the lesser of four percent (4%) of such late payment, or the maximum
amount permitted by law, for the purpose of defraying the expense incurred by
Holder in handling and processing such delinquent payment, and such amount shall
be secured by the Deed of Trust.


                                      -5-
<PAGE>   101
      In addition to any late payment charge which may be due under this Note,
Maker shall pay interest on all sums due hereunder at a rate (the "Default
Rate") equal to the lesser of (i) the Interest Rate plus four percent (4%) per
annum, or (ii) the maximum rate permitted by law, from and after the first to
occur of the following events: if Holder elects to cause the Acceleration of
Maturity or if a petition under Title 11, United States Code, shall be filed by
or against Maker.

      7. Collection and Enforcement Costs. Maker, upon demand, shall pay Holder
for all costs and expenses, including without limitation attorneys' fees, paid
or incurred by Holder in connection with the collection of any sum due
hereunder, or in connection with enforcement of any of Holder's rights or
Maker's obligations under this Note, the Deed of Trust or any of the other Loan
Documents.

      8. Continuing Liability. The obligation of Maker to pay the Principal
Indebtedness, interest and all other sums due hereunder shall continue in full
force and effect and in no ways be impaired, until the actual payment thereof to
Holder, and in case of a sale or transfer of all or any part of the Security, or
in case of any further agreement given to secure the payment of this Note, or in
case of any agreement or stipulation extending the time or modifying the terms
of payment above recited, Maker shall nevertheless continue to be liable on this
Note, as extended or modified by any such agreement or stipulation, unless
released and discharged in writing by Holder.

      9. Joint and Several Liability. If more than one person, corporation,
partnership or other entity shall execute this Note, then each person and entity
shall be fully liable for all obligations of Maker hereunder, and such
obligations shall be joint and several.

      10. No Oral Changes; Waivers. This Note may not be changed orally, but
only by an agreement in writing signed by the party against whom enforcement of
a change is sought. The provisions of this Note shall extend and be applicable
to all renewals, amendments, extensions, consolidations, and modifications of
the Deed of Trust and/or the other Loan Documents, and any


                                      -6-
<PAGE>   102
and all references herein to the Deed of Trust and/or the Loan Documents shall
be deemed to include any such renewals, amendments, extensions, consolidations,
or modifications thereof.

      Maker and any future indorsers, sureties, and guarantors hereof, jointly
and severally, waive presentment for payment, demand, notice of nonpayment,
notice of dishonor, protest of any dishonor, notice of protest, and protest of
this Note, and all other notices in connection with the delivery, acceptance,
performance, default (except notice of default required hereby, if any), or
enforcement of the payment of this Note, and they agree that the liability of
each of them shall be unconditional without regard to the liability of any other
party and shall not be in any manner affected by any indulgence, extension of
time, renewal, waiver, or modification granted or consented to by the Holder;
and Maker and all future indorsers, sureties and guarantors hereof consent to
any and all extensions of time, renewals, waivers, or modifications that may be
granted by the Holder hereof with respect to the payment or other provisions of
this Note, and to the release of the collateral, or any part thereof, with or
without substitution, and agree that additional makers, indorsers, guarantors,
or sureties may become parties hereto without notice to them or affecting their
liability hereunder.

      Holder shall not by any act of omission or commission be deemed to waive
any of its rights or remedies hereunder unless such waiver be in writing and
signed by Holder, and then only to the extent specifically set forth therein; a
waiver on one event shall not be construed as continuing or as a bar to or
waiver of such right or remedy on a subsequent event. The acceptance by Holder
of payment hereunder that is less than payment in full of all amounts due at the
time of such payment shall not without the express written consent of Holder:
(i) constitute a waiver of the right to exercise any of Holder's remedies at
that time or at any subsequent time, (ii) constitute an accord and satisfaction,
or (iii) nullify any prior exercise of any remedy.

      No failure to cause an Acceleration of Maturity hereof by reason of an
Event of Default hereunder, acceptance of a past due installment, or indulgences
granted from time to time shall be construed (i) as a novation of


                                      -7-
<PAGE>   103
this Note or as a reinstatement of the indebtedness evidenced hereby or as a
waiver of such right of acceleration or of the right of Holder thereafter to
insist upon strict compliance with the terms of this Note, or (ii) to prevent
the exercise of such right of acceleration or any other right granted hereunder
or by the laws of the State of Colorado; and, to the maximum extent permitted by
law, Maker hereby expressly waives the benefit of any statute or rule of law or
equity now provided, or which may hereafter be provided, which would produce a
result contrary to or in conflict with the foregoing.

      To the maximum extent permitted by law, Maker hereby waives and renounces
for itself, its heirs, successors and assigns, all rights to the benefits of any
statute of limitations and any moratorium, reinstatement, marshalling,
forbearance, valuation, stay, extension, redemption, and appraisement now
provided, or which may hereafter be provided, by the Constitution and laws of
the United States of America and of any state thereof, both as to itself and in
and to all of its property, real and personal, against the enforcement and
collection of the obligations evidenced by this Note.

      11. Bind and Inure. This Note shall bind and inure to the benefit of the
parties hereto and their respective legal representatives, heirs, successors and
assigns.

      12. Applicable Law. The provisions of this Note shall be construed and
enforceable in accordance with the laws of the State of Colorado.

      If any provision of this Note or the application hereof to any person or
circumstance shall, for any reason and to any extent, be invalid or
unenforceable, neither the remainder of this Note nor the application of such
provision to any other person or circumstance shall be affected thereby, but
rather the same shall be enforced to the greatest extent permitted by law,
except that if such provision would result in a reduction in the Interest Rate
or other material change in the payment of a monetary sum, then the Holder may,
at its option, declare the entire indebtedness evidenced hereby due and payable
upon sixty (60) days prior written notice to Maker and, provided no


                                      -8-
<PAGE>   104
Event of Default is then continuing, without prepayment fee or premium.

      13. Usury. In no event shall Maker be bound to pay interest in excess of
the limit for the use, forbearance or detention of the money loaned pursuant to
this Note; the right to demand any such excess being hereby expressly waived by
Holder.

      14. Notice. Any notice, request, demand, statement or consent made
hereunder shall be in writing signed by the party giving such notice, request,
demand, statement or consent, and shall be deemed to have been properly given
when either delivered personally, delivered to a reputable overnight delivery
service providing a receipt or deposited in the United States Mail, postage
prepaid and registered or certified return receipt requested, at the address set
forth below, or at such other address within the continental United States of
America as may have theretofore been designated in writing. The effective date
of any notice given as aforesaid shall be the date of personal service, one (1)
business day after delivery to such overnight delivery service, or three (3)
business days after being deposited in the United States Mail, whichever is
applicable. For purposes hereof, the addresses are as follows:


            If to Holder:       Massachusetts Mutual Life Insurance Company
                                1295 State Street
                                Springfield, MA 01111
                                Telecopy No.: (413) 744-6123
                                Attn: ITS: Senior Managing Director of
                                                   Real Estate

            With copies to:     Connecticut General Life Insurance Company
                                c/o CIGNA Investments, Inc.
                                900 Cottage Grove Road
                                Hartford, CT  06152-2319
                                Attn:  Investment Services, S-319

                                And


            With a copy to:     CIGNA Corporation
                                Investment Law Department
                                900 Cottage Grove Road
                                Hartford, CT  06152-2215
                                Attn:  Real Estate Division, S-215A


                                      -9-
<PAGE>   105
                                And

                                American General Realty Advisors, Inc.
                                2929 Allen Pkwy., 34th Floor
                                Houston, TX 77019
                                Telecopy No.: (713) 831-1033
                                Attn: Director, Mortgage Loans

            With a courtesy
            copy to:            Fairfield and Woods, P.C.
                                1700 Lincoln Street, Suite 2400
                                Denver, Colorado 80203
                                Attn: Thomas P. Kearns, Esq.

            If to Maker:        Cornerstone Properties Inc.
                                126 East 56th Street
                                New York, New York 10022
                                Attn: Kevin P. Mahoney

            With a courtesy
            copy to:            Shearman & Sterling
                                 Citicorp Center
                                153 East 53rd Street
                                New York City, N.Y. 10022-4676
                                Attn: Timothy G. Little, Esq.


      Notwithstanding the foregoing agreement to provide a courtesy copy to
Maker's attorneys, such copy shall be a courtesy copy only, and failure to
provide such courtesy copy shall have absolutely no effect or entitle Maker to
any remedy whatsoever. Any notice duly given to Maker shall be effective whether
or not the courtesy copy was given to Maker's attorneys.

      15. Nonrecourse. Except as specifically provided hereinafter in this
Section 15 and in Section 40 of the Deed of Trust, neither Maker, Cornerstone
Properties Inc. ("Cornerstone"), nor any of the general or limited partners of
Maker nor any of their respective officers, directors, shareholders, agents,
employees or representatives (collectively the "Exculpated Parties") shall be
personally liable for the payment of any sums due hereunder or the performance
of any obligations of Maker hereunder or under the other Loan Documents. No
judgment for the repayment of the Principal Indebtedness or interest thereon or
any other amount payable pursuant to any of the Loan Documents, will be enforced
against any of the Exculpated Parties personally or any property of any of the
Exculpated Parties other than the Security and any other security


                                      -10-
<PAGE>   106
now or hereafter expressly granted under the Loan Documents in any action to
foreclose the Deed of Trust or to otherwise realize upon any security now or
hereafter expressly granted under the Loan Documents or to collect any amount
payable hereunder. Notwithstanding the foregoing:

            (a) Nothing herein contained shall be construed as prohibiting
      Holder from exercising any and all remedies which the Loan Documents
      permit, including the right to bring actions or proceedings against Maker,
      Cornerstone, and other Exculpated Parties and to enter a judgment against
      Maker, Cornerstone, and any other Exculpated Parties, so long as the
      exercise of any remedy does not extend to execution against or recovery
      out of any property of Maker, Cornerstone, or any other Exculpated Party
      other than the security now or hereafter expressly granted under the Loan
      Documents;

            (b) Maker and Cornerstone shall each be fully and personally liable
      for, and the other Exculpated Parties (to the extent the other Exculpated
      Parties would be liable outside of the provisions of this section) shall
      be fully and personally liable for, (i) misapplying any condemnation
      awards or insurance awards attributable to the Security, to the full
      extent of such awards so misapplied, (ii) misapplying any security
      deposits attributable to the Security, to the full extent of such deposits
      so misapplied, (iii) collecting any rents more than thirty (30) days in
      advance in violation of any covenant contained in the Loan Documents, to
      the full extent of such rents so collected in advance, (iv) committing
      fraud or intentional misrepresentation in connection with the operation of
      the Security or the making of the loan evidenced hereby, to the full
      extent of any loss, damage, expense or costs (including reasonable
      attorneys' fees) incurred by Holder resulting from such fraud,
      misrepresentation or waste, (v) failing to pay in order of priority: real
      estate taxes or assessments, (or escrow accounts established therefor),
      operating and maintenance expenses relating to the Real Property, other
      sums required by the Loan Documents, deposits into a required reserve
      account, capital expenditures, management fees, leasing fees and expenses,
      marketing and advertising costs and debt


                                      -11-
<PAGE>   107
      service or other amounts due on the Indebtedness, but only to the extent
      of any gross revenues from the Security that were available to pay such
      expenses but were not so used during the period beginning six (6) months
      prior to either (A) Maker's receipt of notice of default under the loan
      documents or (B) the occurrence of a default under the loan documents that
      would not require notice in order to ripen into an event of default, and
      continuing through the date Holder takes title to the Real Property; (vi)
      the seizure or forfeiture of the Security due to the criminal activity by
      Maker or Cornerstone any constituent partner of Maker or Cornerstone or
      any of their respective shareholders, partners, officers, employees or
      agents, in the full amount of the loss incurred by Holder as a result of
      such seizure or forfeiture.

            (c) This section shall impose no limitation on Maker's,
      Cornerstone's, or any other Exculpated Party's personal liability under
      and the exercise of any of Holder's rights under any indemnity from Maker,
      Cornerstone, or any other Exculpated Party to Holder including but not
      limited to, the Environmental Indemnification Agreement of even date
      herewith from Maker and Cornerstone to Payee with regard to the Security
      except as may be expressly set forth therein;

            (d) This section shall impose no limitation on or prejudice to the
      rights of Holder to proceed against any entity or person whatsoever,
      including Maker, Cornerstone, and the other Exculpated Parties, with
      respect to the enforcement of any guarantees of the Principal Indebtedness
      or other sums due hereunder or under any of the other Loan Documents or
      any part thereof, any master leases, or any similar rights of payment that
      may be entered into after the date hereof, except as may be expressly set
      forth in any such guarantee.

      16. Time of the Essence. Time is of the essence in this Note and the other
Loan Documents.

      17. Attorneys' Fees. Any reference to "attorney fees" in this document
includes but is not limited to both the fees, charges and costs


                                      -12-
<PAGE>   108
incurred by Holder through its retention of outside legal counsel and the
reasonably allocable fees, costs and charges for services rendered by Holder's
in-house counsel. Any reference to "attorney fees" shall also include but not be
limited to those attorneys or legal fees, costs and charges incurred by Holder
in the collection of any Indebtedness, the enforcement of any obligations
hereunder, the protection of the Security, the foreclosure of the Deed of Trust,
the sale of the Security, the defense of actions arising hereunder and the
collection, protection or setoff of any claim the Holder may have in a
proceeding under Title 11, United States Code. Attorneys fees provided for
hereunder shall accrue whether or not Holder has provided notice of an Event of
Default or of an intention to exercise its remedies for such Event of Default.

      18. Action by Maker. Unless otherwise required by law, Maker may not take
any action with respect to this Note, including, without limitation, any
election to prepay the Principal Indebtedness, unless Maker takes the same
action with respect to those two certain promissory notes of even date herewith
given by Maker to (a) Connecticut General Life Insurance Company in the original
principal amount of $32,666,666, and (b) American General Life Insurance Company
in the original principal amount of $32,666,667.

      19. Waiver of Trial by Jury. Maker hereby waives its right to a trial by
jury as to any matter arising out of or concerning the subject matter of this
Note.

      IN WITNESS WHEREOF, Maker has duly executed this Note as a sealed
instrument as of the day and year first above written.

                                    MAKER:

                                    1700 LINCOLN LIMITED

                                    By:  ARICO-Denver, Inc., general partner


                                         By: ________________________________
                                             Name:  Kevin P. Mahoney
                                             Title:  Vice President


                                      -13-
<PAGE>   109
                                         By: ________________________________
                                             Name:  Scott M. Dalrymple
                                             Title:  Vice President




                                    By:  1700 Lincoln, Inc., general partner


                                         By: ________________________________
                                             Name:  Kevin P. Mahoney
                                             Title:  Vice President


                                         By: ________________________________
                                             Name:  Scott M. Dalrymple
                                             Title:  Vice President


                                      -14-
<PAGE>   110
                                                                Denver, Colorado



                                 PROMISSORY NOTE
                  (CONNECTICUT GENERAL LIFE INSURANCE COMPANY)


$32,666,666                                                        July 23, 1996



      FOR VALUE RECEIVED, 1700 Lincoln Limited (hereinafter referred to as
"Maker"), promises to pay to the order of Connecticut General Life Insurance
Company, a Connecticut corporation, having its principal office at 900 Cottage
Grove Road, Bloomfield, Connecticut (the "Payee"), or such other place as the
Holder hereof may designate in writing (the legal holder from time to time of
this Note, including Payee as the initial holder, hereinafter referred to as
"Holder"), the principal sum of THIRTY-TWO MILLION SIX HUNDRED SIXTY-SIX
THOUSAND SIX HUNDRED SIXTY-SIX AND NO/100 DOLLARS ($32,666,666), or so much
thereof as may be advanced to or for the benefit of Maker by Holder (hereinafter
referred to as "Principal Indebtedness"), together with interest thereon at an
annual rate of seven and one-half percent (7.5%) (the "Interest Rate"), in
accordance with the provisions hereinafter set forth.

      1. Terms of Payment. If the date on which Principal Indebtedness is
advanced to Maker ("the Advancement Date") is not the first day of a calendar
month, then Maker shall pay to Holder on the first day of the first calendar
month following the Advancement Date, interest only on the Principal
Indebtedness, at the Interest Rate, calculated on the basis of a 365-day year
and the number of days from and including the Advancement Date to and including
the last day of the calendar month in which the Advancement Date occurs. On the
first day of the second calendar month following the Advancement Date (or on the
first day of the first calendar month following the date of this Note, if the
date of this Note is the first day of a calendar month), and on the first day of
each calendar month thereafter (hereinafter called the "monthly payment dates")
until July 1, 2001, Maker shall pay to Holder the sum of $228,410.07
(hereinafter referred to as "monthly payments"), to be applied first to interest
on the Principal Indebtedness from time to time outstanding at the Interest Rate
and the balance to be applied in reduction of the Principal Indebtedness. The
interest component of the monthly payments shall be calculated and applied on
the basis of a 360-day year consisting of twelve 30-day months. On August 1,
2001 (the "Maturity
<PAGE>   111
Date"), subject to extension in accordance with that certain Extension Option
Agreement of even date herewith between Maker and Holder, Maker shall pay to
Holder the entire Principal Indebtedness then remaining unpaid, together with
accrued and unpaid interest thereon at the Interest Rate and any other charges
due under this Note, the Deed of Trust (hereinafter defined), and any other
documents evidencing or securing or pertaining to the advancement or
disbursement of the Principal Indebtedness (collectively, the "Loan Documents").
The period from and including the date hereof to the Maturity Date, as the same
may be extended, will be referred to hereinafter as the "Term".

      2. Prepayment. The term "Loan Years" shall mean the consecutive 12-month
periods measured from the first day of the calendar month following the date of
this Note or, if the date of this Note is the first day of a calendar month,
then measured from the date of this Note. Except as specifically provided herein
or in the Deed of Trust, no prepayment of the Principal Indebtedness shall be
allowed during the first two (2) Loan Years (the "Closed Period"). Maker,
whether or not a debtor in a proceeding under Title 11, United States Code, may
prepay the Principal Indebtedness in full, but not in part, on any monthly
payment date after the Closed Period, provided Maker gives Holder forty-five
(45) days' prior written notice and pays a prepayment fee as described below.

      After the Closed Period the prepayment fee shall be calculated as follows:

            (a)   Through the end of the fourth Loan Year, or, if the Term is
                  extended as provided in that certain Extension Option
                  Agreement of even date herewith between Maker and Holder,
                  through the end of the ninth Loan Year, the greater of:

                  (i)   one percent (1%) of the then-existing balance of this
                        Note, or

                  (ii)  Yield Maintenance as defined below.


                                       -2-
<PAGE>   112
            (b)   For the first nine (9) months of the fifth Loan Year,
                  excluding any period after the Extension Notice, if any, and,
                  for the first nine months of the tenth Loan Year, if
                  applicable, Yield Maintenance as defined below.

      The loan may be prepaid at par during the last three (3) months of the
Term, as the Term may be extended pursuant to the Extension Option Agreement
(the "Open Period"). The foregoing prepayment fee will be due when the loan is
prepaid after the Closed Period and prior to the Open Period, whether such
prepayment is voluntary or results from default, acceleration or any other
cause. Such prepayment fee will not be payable if such prepayment results from a
casualty or condemnation and the application of insurance proceeds or
condemnation awards to the loan.

      In the event of a prepayment during the Closed Period resulting from an
acceleration by reason of Maker's default or any other reason, Maker shall pay
to Holder a default prepayment fee calculated as follows:

            (a)   3% of the then-existing principal balance of this Note, plus

            (b)   Yield Maintenance as defined below:

      Yield Maintenance: Yield Maintenance is defined as the sum of the present
values on the date of prepayment of each Monthly Interest Shortfall for the
remaining Term of the loan discounted to present value at one-twelfth of the sum
of the monthly Treasury Yield plus 50 basis points.

      The Monthly Interest Shortfall is calculated for each monthly payment and
is the product of (i) the positive difference, if any, of the Semi-Annual
Equivalent Rate less an amount equal to the Treasury Yield plus 50 basis points,
divided by 12, times (ii) the principal balance of the loan that would have been
outstanding on each monthly payment date for which the calculation is made for
each full and partial month remaining in the Term, assuming that the loan had
not been prepaid, that all payments due on the Loan had been made


                                      -3-
<PAGE>   113
on their respective due dates and that all such assumed payments had been
applied first to accrued interest and then to principal.

      The present value for each Monthly Interest Shortfall amount is then
determined by discounting each Monthly Interest Shortfall to the present value
as of the date of prepayment of the Loan at one-twelfth the sum of the Treasury
Yield plus 50 basis points.

      The "Semi-Annual Equivalent Rate" for this loan is 7.62%.

      The "Treasury Yield" will be determined by reference to the Federal
Reserve Statistical Release H.15 (519) of Selected Interest Rates (or any
similar successor publication of the Federal Reserve) for the first week ending
not less than two full weeks prior to the prepayment date. If the remaining Term
is less than one year, the Treasury Yield will equal the yield for 1-Year
Treasury Constant Maturities. If the remaining Term is equal to one of the
maturities of the Treasury Constant Maturities (e.g., 1-year, 2-year, etc.),
then the Treasury Yield will equal the yield for the Treasury Constant Maturity
with a maturity equaling the remaining Term. If the remaining Term is longer
than one year, but does not equal one of the maturities of the Treasury Constant
Maturities, then the Treasury Yield will be interpolated on a straight-line
basis based on the Yields for the Treasury Constant Maturities with a maturity
closest to the remaining Term.

      The aforementioned prepayment fee does not constitute a penalty, but
rather represents the reasonable estimate, agreed to between Maker and Payee, of
a fair compensation for the loss that may be sustained by Holder due to
prepayment of the Principal Indebtedness prior to the Maturity Date. Any
prepayment fee required pursuant to the preceding paragraphs shall be paid
without prejudice to the right of Holder to collect any of the amounts owing
under this Note or the Deed of Trust or otherwise, to enforce any of its rights
or remedies arising out of an Event of Default hereunder.

      3. Security. This Note is secured by, among other things, a deed of trust
(hereinafter referred to as the "Deed of Trust") given by Maker for the


                                      -4-
<PAGE>   114
benefit of Payee and others, of even date herewith, constituting a first lien on
real estate and a first priority security interest in personal property and any
leasehold in such personal property and an assignment of rents and leases
(hereinafter collectively referred to as the "Security"), in the County of
Denver, State of Colorado.

      4. Location and Medium of Payments. The sums payable under this Note or
under the Deed of Trust shall be paid to Holder at its principal address
hereinabove set forth, or at such other place as Holder may from time to time
hereafter designate to Maker in writing, in legal tender of the United States of
America.

      5. Acceleration of Maturity. At the option of Holder, which may be
exercised at any time after one or more of the following events (each being an
"Event of Default") shall have occurred, the whole of the Principal
Indebtedness, together with all interest and other charges due under any of the
Loan Documents, shall immediately become due and payable ("Acceleration of
Maturity"): (a) if any payment of any installment of the Principal Indebtedness,
and/or interest or of any other sum due hereunder is not received by Holder
within five business days following the date when such payment was due; or (b)
if a default or an Event of Default shall occur under the Deed of Trust or any
other of the Loan Documents, which is not cured within any applicable grace
period afforded therein, if any.

      6. Late Charges; Interest Following Event of Default. If any payment of
principal or interest due under this Note or any escrow payment required under
Section 5 of the Deed of Trust is not paid when due, without regard to any cure
or grace period, Maker shall pay and Holder shall be entitled to collect a late
payment charge for each month or fraction thereof during which such payment is
not made when due and for each month thereafter that such sum remains unpaid,
equal to the lesser of four percent (4%) of such late payment, or the maximum
amount permitted by law, for the purpose of defraying the expense incurred by
Holder in handling and processing such delinquent payment, and such amount shall
be secured by the Deed of Trust.


                                      -5-
<PAGE>   115
      In addition to any late payment charge which may be due under this Note,
Maker shall pay interest on all sums due hereunder at a rate (the "Default
Rate") equal to the lesser of (i) the Interest Rate plus four percent (4%) per
annum, or (ii) the maximum rate permitted by law, from and after the first to
occur of the following events: if Holder elects to cause the Acceleration of
Maturity or if a petition under Title 11, United States Code, shall be filed by
or against Maker.

      7. Collection and Enforcement Costs. Maker, upon demand, shall pay Holder
for all costs and expenses, including without limitation attorneys' fees, paid
or incurred by Holder in connection with the collection of any sum due
hereunder, or in connection with enforcement of any of Holder's rights or
Maker's obligations under this Note, the Deed of Trust or any of the other Loan
Documents.

      8. Continuing Liability. The obligation of Maker to pay the Principal
Indebtedness, interest and all other sums due hereunder shall continue in full
force and effect and in no ways be impaired, until the actual payment thereof to
Holder, and in case of a sale or transfer of all or any part of the Security, or
in case of any further agreement given to secure the payment of this Note, or in
case of any agreement or stipulation extending the time or modifying the terms
of payment above recited, Maker shall nevertheless continue to be liable on this
Note, as extended or modified by any such agreement or stipulation, unless
released and discharged in writing by Holder.

      9. Joint and Several Liability. If more than one person, corporation,
partnership or other entity shall execute this Note, then each person and entity
shall be fully liable for all obligations of Maker hereunder, and such
obligations shall be joint and several.

      10. No Oral Changes; Waivers. This Note may not be changed orally, but
only by an agreement in writing signed by the party against whom enforcement of
a change is sought. The provisions of this Note shall extend and be applicable
to all renewals, amendments, extensions, consolidations, and modifications of
the Deed of Trust and/or the other Loan Documents, and any


                                      -6-
<PAGE>   116
and all references herein to the Deed of Trust and/or the Loan Documents shall
be deemed to include any such renewals, amendments, extensions, consolidations,
or modifications thereof.

      Maker and any future indorsers, sureties, and guarantors hereof, jointly
and severally, waive presentment for payment, demand, notice of nonpayment,
notice of dishonor, protest of any dishonor, notice of protest, and protest of
this Note, and all other notices in connection with the delivery, acceptance,
performance, default (except notice of default required hereby, if any), or
enforcement of the payment of this Note, and they agree that the liability of
each of them shall be unconditional without regard to the liability of any other
party and shall not be in any manner affected by any indulgence, extension of
time, renewal, waiver, or modification granted or consented to by the Holder;
and Maker and all future indorsers, sureties and guarantors hereof consent to
any and all extensions of time, renewals, waivers, or modifications that may be
granted by the Holder hereof with respect to the payment or other provisions of
this Note, and to the release of the collateral, or any part thereof, with or
without substitution, and agree that additional makers, indorsers, guarantors,
or sureties may become parties hereto without notice to them or affecting their
liability hereunder.

      Holder shall not by any act of omission or commission be deemed to waive
any of its rights or remedies hereunder unless such waiver be in writing and
signed by Holder, and then only to the extent specifically set forth therein; a
waiver on one event shall not be construed as continuing or as a bar to or
waiver of such right or remedy on a subsequent event. The acceptance by Holder
of payment hereunder that is less than payment in full of all amounts due at the
time of such payment shall not without the express written consent of Holder:
(i) constitute a waiver of the right to exercise any of Holder's remedies at
that time or at any subsequent time, (ii) constitute an accord and satisfaction,
or (iii) nullify any prior exercise of any remedy.

      No failure to cause an Acceleration of Maturity hereof by reason of an
Event of Default hereunder, acceptance of a past due installment, or indulgences
granted from time to time shall be construed (i) as a novation of


                                      -7-
<PAGE>   117
this Note or as a reinstatement of the indebtedness evidenced hereby or as a
waiver of such right of acceleration or of the right of Holder thereafter to
insist upon strict compliance with the terms of this Note, or (ii) to prevent
the exercise of such right of acceleration or any other right granted hereunder
or by the laws of the State of Colorado; and, to the maximum extent permitted by
law, Maker hereby expressly waives the benefit of any statute or rule of law or
equity now provided, or which may hereafter be provided, which would produce a
result contrary to or in conflict with the foregoing.

      To the maximum extent permitted by law, Maker hereby waives and renounces
for itself, its heirs, successors and assigns, all rights to the benefits of any
statute of limitations and any moratorium, reinstatement, marshalling,
forbearance, valuation, stay, extension, redemption, and appraisement now
provided, or which may hereafter be provided, by the Constitution and laws of
the United States of America and of any state thereof, both as to itself and in
and to all of its property, real and personal, against the enforcement and
collection of the obligations evidenced by this Note.

      11. Bind and Inure. This Note shall bind and inure to the benefit of the
parties hereto and their respective legal representatives, heirs, successors and
assigns.

      12. Applicable Law. The provisions of this Note shall be construed and
enforceable in accordance with the laws of the State of Colorado.

      If any provision of this Note or the application hereof to any person or
circumstance shall, for any reason and to any extent, be invalid or
unenforceable, neither the remainder of this Note nor the application of such
provision to any other person or circumstance shall be affected thereby, but
rather the same shall be enforced to the greatest extent permitted by law,
except that if such provision would result in a reduction in the Interest Rate
or other material change in the payment of a monetary sum, then the Holder may,
at its option, declare the entire indebtedness evidenced hereby due and payable
upon sixty (60) days prior written notice to Maker and, provided no


                                      -8-
<PAGE>   118
Event of Default is then continuing, without prepayment fee or premium.

      13. Usury. In no event shall Maker be bound to pay interest in excess of
the limit for the use, forbearance or detention of the money loaned pursuant to
this Note; the right to demand any such excess being hereby expressly waived by
Holder.

      14. Notice. Any notice, request, demand, statement or consent made
hereunder shall be in writing signed by the party giving such notice, request,
demand, statement or consent, and shall be deemed to have been properly given
when either delivered personally, delivered to a reputable overnight delivery
service providing a receipt or deposited in the United States Mail, postage
prepaid and registered or certified return receipt requested, at the address set
forth below, or at such other address within the continental United States of
America as may have theretofore been designated in writing. The effective date
of any notice given as aforesaid shall be the date of personal service, one (1)
business day after delivery to such overnight delivery service, or three (3)
business days after being deposited in the United States Mail, whichever is
applicable. For purposes hereof, the addresses are as follows:


            If to Holder:       Connecticut General Life Insurance Company
                                c/o CIGNA Investments, Inc.
                                900 Cottage Grove Road
                                Hartford, CT  06152-2319
                                Attn:  Investment Services, S-319

            With copies to:     American General Realty Advisors, Inc.
                                2929 Allen Pkwy., 34th Floor
                                Houston, TX 77019
                                Telecopy No.: (713) 831-1033
                                Attn: Director, Mortgage Loans

                                And

                                Massachusetts Mutual Life Insurance Company
                                1295 State Street
                                Springfield, MA 01111
                                Telecopy No.: (413) 744-6123
                                Attn: ITS: Senior Managing Director of
                                                   Real Estate

            With a copy to:     CIGNA Corporation


                                      -9-
<PAGE>   119
                                Investment Law Department
                                900 Cottage Grove Road
                                Hartford, CT  06152-2215
                                Attn:  Real Estate Division, S-215A

            With a courtesy
            copy to:            Fairfield and Woods, P.C.
                                1700 Lincoln Street, Suite 2400
                                Denver, Colorado 80203
                                Attn: Thomas P. Kearns, Esq.

            If to Maker:        Cornerstone Properties Inc.
                                126 East 56th Street
                                New York, New York 10022
                                Attn: Kevin P. Mahoney

            With a courtesy
            copy to:            Shearman & Sterling
                                Citicorp Center
                                153 East 53rd Street
                                New York City, N.Y. 10022-4676
                                Attn: Timothy G. Little, Esq.


      Notwithstanding the foregoing agreement to provide a courtesy copy to
Maker's attorneys, such copy shall be a courtesy copy only, and failure to
provide such courtesy copy shall have absolutely no effect or entitle Maker to
any remedy whatsoever. Any notice duly given to Maker shall be effective whether
or not the courtesy copy was given to Maker's attorneys.

      15. Nonrecourse. Except as specifically provided hereinafter in this
Section 15 and in Section 40 of the Deed of Trust, neither Maker, Cornerstone
Properties Inc. ("Cornerstone"), nor any of the general or limited partners of
Maker nor any of their respective officers, directors, shareholders, agents,
employees or representatives (collectively the "Exculpated Parties") shall be
personally liable for the payment of any sums due hereunder or the performance
of any obligations of Maker hereunder or under the other Loan Documents. No
judgment for the repayment of the Principal Indebtedness or interest thereon or
any other amount payable pursuant to any of the Loan Documents, will be enforced
against any of the Exculpated Parties personally or any property of any of the
Exculpated Parties other than the Security and any other security now or
hereafter expressly granted under the Loan Documents in any action to foreclose
the Deed of Trust or to otherwise realize upon any security now or 


                                      -10-
<PAGE>   120
hereafter expressly granted under the Loan Documents or to collect any amount
payable hereunder. Notwithstanding the foregoing:

            (a) Nothing herein contained shall be construed as prohibiting
      Holder from exercising any and all remedies which the Loan Documents
      permit, including the right to bring actions or proceedings against Maker,
      Cornerstone, and other Exculpated Parties and to enter a judgment against
      Maker, Cornerstone, and any other Exculpated Parties, so long as the
      exercise of any remedy does not extend to execution against or recovery
      out of any property of Maker, Cornerstone, or any other Exculpated Party
      other than the security now or hereafter expressly granted under the Loan
      Documents;

            (b) Maker and Cornerstone shall each be fully and personally liable
      for, and the other Exculpated Parties (to the extent the other Exculpated
      Parties would be liable outside of the provisions of this section) shall
      be fully and personally liable for, (i) misapplying any condemnation
      awards or insurance awards attributable to the Security, to the full
      extent of such awards so misapplied, (ii) misapplying any security
      deposits attributable to the Security, to the full extent of such deposits
      so misapplied, (iii) collecting any rents more than thirty (30) days in
      advance in violation of any covenant contained in the Loan Documents, to
      the full extent of such rents so collected in advance, (iv) committing
      fraud or intentional misrepresentation in connection with the operation of
      the Security or the making of the loan evidenced hereby, to the full
      extent of any loss, damage, expense or costs (including reasonable
      attorneys' fees) incurred by Holder resulting from such fraud,
      misrepresentation or waste, (v) failing to pay in order of priority: real
      estate taxes or assessments, (or escrow accounts established therefor),
      operating and maintenance expenses relating to the Real Property, other
      sums required by the Loan Documents, deposits into a required reserve
      account, capital expenditures, management fees, leasing fees and expenses,
      marketing and advertising costs and debt service or other amounts due on
      the Indebtedness, but only to the extent of any gross revenues from the
      Security that were available to pay such


                                      -11-
<PAGE>   121
      expenses but were not so used during the period beginning six (6) months
      prior to either (A) Maker's receipt of notice of default under the loan
      documents or (B) the occurrence of a default under the loan documents that
      would not require notice in order to ripen into an event of default, and
      continuing through the date Holder takes title to the Real Property; (vi)
      the seizure or forfeiture of the Security due to the criminal activity by
      Maker or Cornerstone any constituent partner of Maker or Cornerstone or
      any of their respective shareholders, partners, officers, employees or
      agents, in the full amount of the loss incurred by Holder as a result of
      such seizure or forfeiture.

            (c) This section shall impose no limitation on Maker's,
      Cornerstone's, or any other Exculpated Party's personal liability under
      and the exercise of any of Holder's rights under any indemnity from Maker,
      Cornerstone, or any other Exculpated Party to Holder including but not
      limited to, the Environmental Indemnification Agreement of even date
      herewith from Maker and Cornerstone to Payee with regard to the Security
      except as may be expressly set forth therein;

            (d) This section shall impose no limitation on or prejudice to the
      rights of Holder to proceed against any entity or person whatsoever,
      including Maker, Cornerstone, and the other Exculpated Parties, with
      respect to the enforcement of any guarantees of the Principal Indebtedness
      or other sums due hereunder or under any of the other Loan Documents or
      any part thereof, any master leases, or any similar rights of payment that
      may be entered into after the date hereof, except as may be expressly set
      forth in any such guarantee.

      16. Time of the Essence. Time is of the essence in this Note and the other
Loan Documents.

      17. Attorneys' Fees. Any reference to "attorney fees" in this document
includes but is not limited to both the fees, charges and costs incurred by
Holder through its retention of outside legal counsel and the reasonably
allocable fees, costs and charges for services rendered by Holder's


                                      -12-
<PAGE>   122
in-house counsel. Any reference to "attorney fees" shall also include but not be
limited to those attorneys or legal fees, costs and charges incurred by Holder
in the collection of any Indebtedness, the enforcement of any obligations
hereunder, the protection of the Security, the foreclosure of the Deed of Trust,
the sale of the Security, the defense of actions arising hereunder and the
collection, protection or setoff of any claim the Holder may have in a
proceeding under Title 11, United States Code. Attorneys fees provided for
hereunder shall accrue whether or not Holder has provided notice of an Event of
Default or of an intention to exercise its remedies for such Event of Default.

      18. Action by Maker. Unless otherwise required by law, Maker may not take
any action with respect to this Note, including, without limitation, any
election to prepay the Principal Indebtedness, unless Maker takes the same
action with respect to those two certain promissory notes of even date herewith
given by Maker to (a) American General Life Insurance Company in the original
principal amount of $32,666,667, and (b) Massachusetts Mutual Life Insurance
Company in the original principal amount of $32,666,667.

      19. Waiver of Trial by Jury. Maker hereby waives its right to a trial by
jury as to any matter arising out of or concerning the subject matter of this
Note.

      IN WITNESS WHEREOF, Maker has duly executed this Note as a sealed
instrument as of the day and year first above written.

                                    MAKER:

                                    1700 LINCOLN LIMITED

                                    By:  ARICO-Denver, Inc., general partner


                                         By: ________________________________
                                             Name:  Kevin P. Mahoney
                                             Title:  Vice President


                                         By: ________________________________
                                             Name:  Scott M. Dalrymple


                                      -13-
<PAGE>   123
                                             Title:  Vice President




                                    By:  1700 Lincoln, Inc., general partner


                                         By: ________________________________
                                             Name:  Kevin P. Mahoney
                                             Title:  Vice President


                                         By: ________________________________
                                             Name:  Scott M. Dalrymple
                                             Title:  Vice President


                                      -14-
<PAGE>   124
                                                                Denver, Colorado



                                 PROMISSORY NOTE
                    (AMERICAN GENERAL LIFE INSURANCE COMPANY)


$32,666,667
                                                                   July 23, 1996



         FOR VALUE RECEIVED, 1700 Lincoln Limited (hereinafter referred to as
"Maker"), promises to pay to the order of American General Life Insurance
Company, a Texas corporation, having its principal office at 2929 Allen Parkway,
Houston, Texas 77019 (the "Payee"), or such other place as the Holder hereof may
designate in writing (the legal holder from time to time of this Note, including
Payee as the initial holder, hereinafter referred to as "Holder"), the principal
sum of THIRTY-TWO MILLION SIX HUNDRED SIXTY-SIX THOUSAND SIX HUNDRED SIXTY-SEVEN
AND NO/100 DOLLARS ($32,666,667), or so much thereof as may be advanced to or
for the benefit of Maker by Holder (hereinafter referred to as "Principal
Indebtedness"), together with interest thereon at an annual rate of seven and
one-half percent (7.5%) (the "Interest Rate"), in accordance with the provisions
hereinafter set forth.

         1. Terms of Payment. If the date on which Principal Indebtedness is
advanced to Maker ("the Advancement Date") is not the first day of a calendar
month, then Maker shall pay to Holder on the first day of the first calendar
month following the Advancement Date, interest only on the Principal
Indebtedness, at the Interest Rate, calculated on the basis of a 365-day year
and the number of days from and including the Advancement Date to and including
the last day of the calendar month in which the Advancement Date occurs. On the
first day of the second calendar month following the Advancement Date (or on the
first day of the first calendar month following the date of this Note, if the
date of this Note is the first day of a calendar month), and on the first day of
each calendar month thereafter (hereinafter called the "monthly payment dates")
until July 1, 2001, Maker shall pay to Holder the sum of $228,410.07
(hereinafter referred to as "monthly payments"), to be applied first to interest
on the Principal Indebtedness from time to time outstanding at the Interest Rate
and the balance to be applied in reduction of the Principal Indebtedness. The
interest component of the monthly payments shall be calculated and applied on
the basis of a 360-day year consisting of twelve 30-day months. On August 1,
2001 (the "Maturity 
<PAGE>   125
Date"), subject to extension in accordance with that certain Extension Option
Agreement of even date herewith between Maker and Holder, Maker shall pay to
Holder the entire Principal Indebtedness then remaining unpaid, together with
accrued and unpaid interest thereon at the Interest Rate and any other charges
due under this Note, the Deed of Trust (hereinafter defined), and any other
documents evidencing or securing or pertaining to the advancement or
disbursement of the Principal Indebtedness (collectively, the "Loan Documents").
The period from and including the date hereof to the Maturity Date, as the same
may be extended, will be referred to hereinafter as the "Term".

         2. Prepayment. The term "Loan Years" shall mean the consecutive
12-month periods measured from the first day of the calendar month following the
date of this Note or, if the date of this Note is the first day of a calendar
month, then measured from the date of this Note. Except as specifically provided
herein or in the Deed of Trust, no prepayment of the Principal Indebtedness
shall be allowed during the first two (2) Loan Years (the "Closed Period").
Maker, whether or not a debtor in a proceeding under Title 11, United States
Code, may prepay the Principal Indebtedness in full, but not in part, on any
monthly payment date after the Closed Period, provided Maker gives Holder
forty-five (45) days' prior written notice and pays a prepayment fee as
described below.

         After the Closed Period the prepayment fee shall be calculated as
follows:

                  (a)      Through the end of the fourth Loan Year, or, if the
                           Term is extended as provided in that certain
                           Extension Option Agreement of even date herewith
                           between Maker and Holder, through the end of the
                           ninth Loan Year, the greater of:

                           (i)      one percent (1%) of the then-existing 
                                    balance of this Note, or

                           (ii)     Yield Maintenance as defined below.


                                      - 2-
<PAGE>   126
                  (b)      For the first nine (9) months of the fifth Loan Year,
                           excluding any period after the Extension Notice, if
                           any, and, for the first nine months of the tenth Loan
                           Year, if applicable, Yield Maintenance as defined
                           below.

         The loan may be prepaid at par during the last three (3) months of the
Term, as the Term may be extended pursuant to the Extension Option Agreement
(the "Open Period"). The foregoing prepayment fee will be due when the loan is
prepaid after the Closed Period and prior to the Open Period, whether such
prepayment is voluntary or results from default, acceleration or any other
cause. Such prepayment fee will not be payable if such prepayment results from a
casualty or condemnation and the application of insurance proceeds or
condemnation awards to the loan.

         In the event of a prepayment during the Closed Period resulting from an
acceleration by reason of Maker's default or any other reason, Maker shall pay
to Holder a default prepayment fee calculated as follows:

                  (a)      3% of the then-existing principal balance of this 
                           Note, plus

                  (b)      Yield Maintenance as defined below:

         Yield Maintenance: Yield Maintenance is defined as the sum of the
present values on the date of prepayment of each Monthly Interest Shortfall for
the remaining Term of the loan discounted to present value at one-twelfth of the
sum of the monthly Treasury Yield plus 50 basis points.

         The Monthly Interest Shortfall is calculated for each monthly payment
and is the product of (i) the positive difference, if any, of the Semi-Annual
Equivalent Rate less an amount equal to the Treasury Yield plus 50 basis points,
divided by 12, times (ii) the principal balance of the loan that would have been
outstanding on each monthly payment date for which the calculation is made for
each full and partial month remaining in the Term, assuming that the loan had
not been prepaid, that all payments due on the Loan had been made 


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<PAGE>   127
on their respective due dates and that all such assumed payments had been
applied first to accrued interest and then to principal.

         The present value for each Monthly Interest Shortfall amount is then
determined by discounting each Monthly Interest Shortfall to the present value
as of the date of prepayment of the Loan at one-twelfth the sum of the Treasury
Yield plus 50 basis points.

         The "Semi-Annual Equivalent Rate" for this loan is 7.62%.

         The "Treasury Yield" will be determined by reference to the Federal
Reserve Statistical Release H.15 (519) of Selected Interest Rates (or any
similar successor publication of the Federal Reserve) for the first week ending
not less than two full weeks prior to the prepayment date. If the remaining Term
is less than one year, the Treasury Yield will equal the yield for 1-Year
Treasury Constant Maturities. If the remaining Term is equal to one of the
maturities of the Treasury Constant Maturities (e.g., 1-year, 2-year, etc.),
then the Treasury Yield will equal the yield for the Treasury Constant Maturity
with a maturity equaling the remaining Term. If the remaining Term is longer
than one year, but does not equal one of the maturities of the Treasury Constant
Maturities, then the Treasury Yield will be interpolated on a straight-line
basis based on the Yields for the Treasury Constant Maturities with a maturity
closest to the remaining Term.

         The aforementioned prepayment fee does not constitute a penalty, but
rather represents the reasonable estimate, agreed to between Maker and Payee, of
a fair compensation for the loss that may be sustained by Holder due to
prepayment of the Principal Indebtedness prior to the Maturity Date. Any
prepayment fee required pursuant to the preceding paragraphs shall be paid
without prejudice to the right of Holder to collect any of the amounts owing
under this Note or the Deed of Trust or otherwise, to enforce any of its rights
or remedies arising out of an Event of Default hereunder.

         3. Security. This Note is secured by, among other things, a deed of
trust (hereinafter referred to as the "Deed of Trust") given by Maker for the


                                      - 4-
<PAGE>   128
benefit of Payee and others, of even date herewith, constituting a first lien on
real estate and a first priority security interest in personal property and any
leasehold in such personal property and an assignment of rents and leases
(hereinafter collectively referred to as the "Security"), in the City and County
of Denver, State of Colorado.

         4. Location and Medium of Payments. The sums payable under this Note or
under the Deed of Trust shall be paid to Holder at its principal address
hereinabove set forth, or at such other place as Holder may from time to time
hereafter designate to Maker in writing, in legal tender of the United States of
America.

         5. Acceleration of Maturity. At the option of Holder, which may be
exercised at any time after one or more of the following events (each being an
"Event of Default") shall have occurred, the whole of the Principal
Indebtedness, together with all interest and other charges due under any of the
Loan Documents, shall immediately become due and payable ("Acceleration of
Maturity"): (a) if any payment of any installment of the Principal Indebtedness,
and/or interest or of any other sum due hereunder is not received by Holder
within five business days following the date when such payment was due; or (b)
if a default or an Event of Default shall occur under the Deed of Trust or any
other of the Loan Documents, which is not cured within any applicable grace
period afforded therein, if any.

         6. Late Charges; Interest Following Event of Default. If any payment of
principal or interest due under this Note or any escrow payment required under
Section 5 of the Deed of Trust is not paid when due, without regard to any cure
or grace period, Maker shall pay and Holder shall be entitled to collect a late
payment charge for each month or fraction thereof during which such payment is
not made when due and for each month thereafter that such sum remains unpaid,
equal to the lesser of four percent (4%) of such late payment, or the maximum
amount permitted by law, for the purpose of defraying the expense incurred by
Holder in handling and processing such delinquent payment, and such amount shall
be secured by the Deed of Trust.


                                     - 5 -
<PAGE>   129
         In addition to any late payment charge which may be due under this
Note, Maker shall pay interest on all sums due hereunder at a rate (the "Default
Rate") equal to the lesser of (i) the Interest Rate plus four percent (4%) per
annum, or (ii) the maximum rate permitted by law, from and after the first to
occur of the following events: if Holder elects to cause the Acceleration of
Maturity or if a petition under Title 11, United States Code, shall be filed by
or against Maker.

         7. Collection and Enforcement Costs. Maker, upon demand, shall pay
Holder for all costs and expenses, including without limitation attorneys' fees,
paid or incurred by Holder in connection with the collection of any sum due
hereunder, or in connection with enforcement of any of Holder's rights or
Maker's obligations under this Note, the Deed of Trust or any of the other Loan
Documents.

         8. Continuing Liability. The obligation of Maker to pay the Principal
Indebtedness, interest and all other sums due hereunder shall continue in full
force and effect and in no ways be impaired, until the actual payment thereof to
Holder, and in case of a sale or transfer of all or any part of the Security, or
in case of any further agreement given to secure the payment of this Note, or in
case of any agreement or stipulation extending the time or modifying the terms
of payment above recited, Maker shall nevertheless continue to be liable on this
Note, as extended or modified by any such agreement or stipulation, unless
released and discharged in writing by Holder.

         9. Joint and Several Liability. If more than one person, corporation,
partnership or other entity shall execute this Note, then each person and entity
shall be fully liable for all obligations of Maker hereunder, and such
obligations shall be joint and several.

         10. No Oral Changes; Waivers. This Note may not be changed orally, but
only by an agreement in writing signed by the party against whom enforcement of
a change is sought. The provisions of this Note shall extend and be applicable
to all renewals, amendments, extensions, consolidations, and modifications of
the Deed of Trust and/or the other Loan Documents, and any 


                                     - 6 -
<PAGE>   130
and all references herein to the Deed of Trust and/or the Loan Documents shall
be deemed to include any such renewals, amendments, extensions, consolidations,
or modifications thereof.

         Maker and any future indorsers, sureties, and guarantors hereof,
jointly and severally, waive presentment for payment, demand, notice of
nonpayment, notice of dishonor, protest of any dishonor, notice of protest, and
protest of this Note, and all other notices in connection with the delivery,
acceptance, performance, default (except notice of default required hereby, if
any), or enforcement of the payment of this Note, and they agree that the
liability of each of them shall be unconditional without regard to the liability
of any other party and shall not be in any manner affected by any indulgence,
extension of time, renewal, waiver, or modification granted or consented to by
the Holder; and Maker and all future indorsers, sureties and guarantors hereof
consent to any and all extensions of time, renewals, waivers, or modifications
that may be granted by the Holder hereof with respect to the payment or other
provisions of this Note, and to the release of the collateral, or any part
thereof, with or without substitution, and agree that additional makers,
indorsers, guarantors, or sureties may become parties hereto without notice to
them or affecting their liability hereunder.

         Holder shall not by any act of omission or commission be deemed to
waive any of its rights or remedies hereunder unless such waiver be in writing
and signed by Holder, and then only to the extent specifically set forth
therein; a waiver on one event shall not be construed as continuing or as a bar
to or waiver of such right or remedy on a subsequent event. The acceptance by
Holder of payment hereunder that is less than payment in full of all amounts due
at the time of such payment shall not without the express written consent of
Holder: (i) constitute a waiver of the right to exercise any of Holder's
remedies at that time or at any subsequent time, (ii) constitute an accord and
satisfaction, or (iii) nullify any prior exercise of any remedy.

         No failure to cause an Acceleration of Maturity hereof by reason of an
Event of Default hereunder, acceptance of a past due installment, or indulgences
granted from time to time shall be construed (i) as a novation of 


                                     - 7 -
<PAGE>   131
this Note or as a reinstatement of the indebtedness evidenced hereby or as a
waiver of such right of acceleration or of the right of Holder thereafter to
insist upon strict compliance with the terms of this Note, or (ii) to prevent
the exercise of such right of acceleration or any other right granted hereunder
or by the laws of the State of Colorado; and, to the maximum extent permitted by
law, Maker hereby expressly waives the benefit of any statute or rule of law or
equity now provided, or which may hereafter be provided, which would produce a
result contrary to or in conflict with the foregoing.

         To the maximum extent permitted by law, Maker hereby waives and
renounces for itself, its heirs, successors and assigns, all rights to the
benefits of any statute of limitations and any moratorium, reinstatement,
marshalling, forbearance, valuation, stay, extension, redemption, and
appraisement now provided, or which may hereafter be provided, by the
Constitution and laws of the United States of America and of any state thereof,
both as to itself and in and to all of its property, real and personal, against
the enforcement and collection of the obligations evidenced by this Note.

         11. Bind and Inure. This Note shall bind and inure to the benefit of
the parties hereto and their respective legal representatives, heirs, successors
and assigns.

         12. Applicable Law. The provisions of this Note shall be construed and
enforceable in accordance with the laws of the State of Colorado.

         If any provision of this Note or the application hereof to any person
or circumstance shall, for any reason and to any extent, be invalid or
unenforceable, neither the remainder of this Note nor the application of such
provision to any other person or circumstance shall be affected thereby, but
rather the same shall be enforced to the greatest extent permitted by law,
except that if such provision would result in a reduction in the Interest Rate
or other material change in the payment of a monetary sum, then the Holder may,
at its option, declare the entire indebtedness evidenced hereby due and payable
upon sixty (60) days prior written notice to Maker and, provided no 


                                     - 8 -
<PAGE>   132
Event of Default is then continuing, without prepayment fee or premium.

         13. Usury. In no event shall Maker be bound to pay interest in excess
of the limit for the use, forbearance or detention of the money loaned pursuant
to this Note; the right to demand any such excess being hereby expressly waived
by Holder.

         14. Notice. Any notice, request, demand, statement or consent made
hereunder shall be in writing signed by the party giving such notice, request,
demand, statement or consent, and shall be deemed to have been properly given
when either delivered personally, delivered to a reputable overnight delivery
service providing a receipt or deposited in the United States Mail, postage
prepaid and registered or certified return receipt requested, at the address set
forth below, or at such other address within the continental United States of
America as may have theretofore been designated in writing. The effective date
of any notice given as aforesaid shall be the date of personal service, one (1)
business day after delivery to such overnight delivery service, or three (3)
business days after being deposited in the United States Mail, whichever is
applicable. For purposes hereof, the addresses are as follows:


                  If to Holder:      American General Realty Advisors, Inc.
                                     2929 Allen Pkwy., 34th Floor
                                     Houston, TX 77019
                                     Telecopy No.: (713) 831-1033
                                     Attn: Director, Mortgage Loans

                  With copies to:    Connecticut General Life Insurance Company
                                     c/o CIGNA Investments, Inc.
                                     900 Cottage Grove Road
                                     Hartford, CT 06152-2319
                                     Attn: Investment Services, S-319

                                     And

                                     Massachusetts Mutual Life Insurance Company
                                     1295 State Street
                                     Springfield, MA 01111
                                     Telecopy No.: (413) 744-6123
                                     Attn: ITS: Senior Managing Director of
                                                                 Real Estate

                  With a copy to:    CIGNA Corporation

                                     - 9 -
<PAGE>   133
                                     Investment Law Department
                                     900 Cottage Grove Road
                                     Hartford, CT 06152-2215
                                     Attn:  Real Estate Division, S-215A

                  With a courtesy
                  copy to:           Fairfield and Woods, P.C.
                                     1700 Lincoln Street, Suite 2400
                                     Denver, Colorado 80203
                                     Attn: Thomas P. Kearns, Esq.

                  If to Maker:       Cornerstone Properties Inc.
                                     126 East 56th Street
                                     New York, New York 10022
                                     Attn: Kevin P. Mahoney

                  With a courtesy
                  copy to:           Shearman & Sterling
                                     Citicorp Center
                                     153 East 53rd Street
                                     New York City, N.Y. 10022-4676
                                     Attn: Timothy G. Little, Esq.


         Notwithstanding the foregoing agreement to provide a courtesy copy to
Maker's attorneys, such copy shall be a courtesy copy only, and failure to
provide such courtesy copy shall have absolutely no effect or entitle Maker to
any remedy whatsoever. Any notice duly given to Maker shall be effective whether
or not the courtesy copy was given to Maker's attorneys.

         15. Nonrecourse. Except as specifically provided hereinafter in this
Section 15 and in Section 40 of the Deed of Trust, neither Maker, Cornerstone
Properties Inc. ("Cornerstone"), nor any of the general or limited partners of
Maker nor any of their respective officers, directors, shareholders, agents,
employees or representatives (collectively the "Exculpated Parties") shall be
personally liable for the payment of any sums due hereunder or the performance
of any obligations of Maker hereunder or under the other Loan Documents. No
judgment for the repayment of the Principal Indebtedness or interest thereon or
any other amount payable pursuant to any of the Loan Documents, will be enforced
against any of the Exculpated Parties personally or any property of any of the
Exculpated Parties other than the Security and any other security now or
hereafter expressly granted under the Loan Documents in any action to foreclose
the Deed of Trust or to otherwise realize upon any security now or 


                                     - 10 -
<PAGE>   134
hereafter expressly granted under the Loan Documents or to collect any amount
payable hereunder. Notwithstanding the foregoing:

                  (a) Nothing herein contained shall be construed as prohibiting
         Holder from exercising any and all remedies which the Loan Documents
         permit, including the right to bring actions or proceedings against
         Maker, Cornerstone, and other Exculpated Parties and to enter a
         judgment against Maker, Cornerstone, and any other Exculpated Parties,
         so long as the exercise of any remedy does not extend to execution
         against or recovery out of any property of Maker, Cornerstone, or any
         other Exculpated Party other than the security now or hereafter
         expressly granted under the Loan Documents;

                  (b) Maker and Cornerstone shall each be fully and personally
         liable for, and the other Exculpated Parties (to the extent the other
         Exculpated Parties would be liable outside of the provisions of this
         section) shall be fully and personally liable for, (i) misapplying any
         condemnation awards or insurance awards attributable to the Security,
         to the full extent of such awards so misapplied, (ii) misapplying any
         security deposits attributable to the Security, to the full extent of
         such deposits so misapplied, (iii) collecting any rents more than
         thirty (30) days in advance in violation of any covenant contained in
         the Loan Documents, to the full extent of such rents so collected in
         advance, (iv) committing fraud or intentional misrepresentation in
         connection with the operation of the Security or the making of the loan
         evidenced hereby, to the full extent of any loss, damage, expense or
         costs (including reasonable attorneys' fees) incurred by Holder
         resulting from such fraud, misrepresentation or waste, (v) failing to
         pay in order of priority: real estate taxes or assessments, (or escrow
         accounts established therefor), operating and maintenance expenses
         relating to the Real Property, other sums required by the Loan
         Documents, deposits into a required reserve account, capital
         expenditures, management fees, leasing fees and expenses, marketing and
         advertising costs and debt service or other amounts due on the
         Indebtedness, but only to the extent of any gross revenues from the
         Security that were available to pay such 


                                     - 11 -
<PAGE>   135
         expenses but were not so used during the period beginning six (6)
         months prior to either (A) Maker's receipt of notice of default under
         the loan documents or (B) the occurrence of a default under the loan
         documents that would not require notice in order to ripen into an event
         of default, and continuing through the date Holder takes title to the
         Real Property; (vi) the seizure or forfeiture of the Security due to
         the criminal activity by Maker or Cornerstone Properties, Inc., any
         constituent partner of Maker or Cornerstone Properties, Inc., or any of
         their respective shareholders, partners, officers, employees or agents,
         in the full amount of the loss incurred by Holder as a result of such
         seizure or forfeiture.

                  (c) This section shall impose no limitation on Maker's,
         Cornerstone's, or any other Exculpated Party's personal liability under
         and the exercise of any of Holder's rights under any indemnity from
         Maker, Cornerstone, or any other Exculpated Party to Holder including
         but not limited to, the Environmental Indemnification Agreement of even
         date herewith from Maker and Cornerstone to Payee with regard to the
         Security except as may be expressly set forth therein;

                  (d) This section shall impose no limitation on or prejudice to
         the rights of Holder to proceed against any entity or person
         whatsoever, including Maker, Cornerstone, and the other Exculpated
         Parties, with respect to the enforcement of any guarantees of the
         Principal Indebtedness or other sums due hereunder or under any of the
         other Loan Documents or any part thereof, any master leases, or any
         similar rights of payment that may be entered into after the date
         hereof, except as may be expressly set forth in any such guarantee.

         16. Time of the Essence. Time is of the essence in this Note and the
other Loan Documents.

         17. Attorneys' Fees. Any reference to "attorney fees" in this document
includes but is not limited to both the fees, charges and costs incurred by
Holder through its retention of outside legal counsel and the 


                                     - 12 -
<PAGE>   136
reasonably allocable fees, costs and charges for services rendered by Holder's
in-house counsel. Any reference to "attorney fees" shall also include but not be
limited to those attorneys or legal fees, costs and charges incurred by Holder
in the collection of any Indebtedness, the enforcement of any obligations
hereunder, the protection of the Security, the foreclosure of the Deed of Trust,
the sale of the Security, the defense of actions arising hereunder and the
collection, protection or setoff of any claim the Holder may have in a
proceeding under Title 11, United States Code. Attorneys fees provided for
hereunder shall accrue whether or not Holder has provided notice of an Event of
Default or of an intention to exercise its remedies for such Event of Default.

         18. Action by Maker. Unless otherwise required by law, Maker may not
take any action with respect to this Note, including, without limitation, any
election to prepay the Principal Indebtedness, unless Maker takes the same
action with respect to those two certain promissory notes of even date herewith
given by Maker to (a) Connecticut General Life Insurance Company in the original
principal amount of $32,666,666, and (b) Massachusetts Mutual Life Insurance
Company in the original principal amount of $32,666,667.

         19. Waiver of Trial by Jury. Maker hereby waives its right to a trial
by jury as to any matter arising out of or concerning the subject matter of this
Note.

         IN WITNESS WHEREOF, Maker has duly executed this Note as a sealed
instrument as of the day and year first above written.

                                     MAKER:

                                     1700 LINCOLN LIMITED

                                     By:   ARICO-Denver, Inc., general partner


                                         By: ________________________________
                                             Name:  Kevin P. Mahoney
                                             Title:  Vice President


                                     - 13 -
<PAGE>   137

                                         By: ________________________________
                                             Name:  Scott M. Dalrymple
                                             Title:  Vice President




                                     By:   1700 Lincoln, Inc., general partner


                                         By: ________________________________
                                             Name:  Kevin P. Mahoney
                                             Title:  Vice President


                                         By: ________________________________
                                             Name:  Scott M. Dalrymple
                                             Title:  Vice President


                                     - 14 -