Document:

Executed in 6 Parts
                                                             Counterpart No. ( )

                              NATIONAL EQUITY TRUST

                            TOP TEN PORTFOLIO SERIES 23

                            REFERENCE TRUST AGREEMENT

     This Reference  Trust Agreement  dated , 2000 among  Prudential  Securities
Incorporated,  as Depositor and The Chase Manhattan Bank, as Trustee, sets forth
certain provisions in full and incorporates other provisions by reference to the
document  entitled  "National  Equity  Trust Low Five  Portfolio  Series,  Trust
Indenture and  Agreement"  (the "Basic  Agreement")  dated April 25, 1995.  Such
provisions  as  are  set  forth  in  full  herein  and  such  provisions  as are
incorporated by reference constitute a single instrument (the "Indenture").

                                WITNESSETH THAT:

     In  consideration  of the  premises  and of the  mutual  agreements  herein
contained, the Depositor and the Trustee agree as follows:

                                     Part I.

                     STANDARD TERMS AND CONDITIONS OF TRUST

     Subject to the provisions of Part II hereof,  all the provisions  contained
in the Basic  Agreement are herein  incorporated  by reference in their entirety
and  shall be deemed  to be a part of this  instrument  as fully and to the same
extent as though said  provisions had been set forth in full in this  instrument
except that the Basic Agreement is hereby amended in the following manner:

     A.   Article I, entitled "Definitions", paragraph 22, shall be amended as
          follows:

               "Trustee  shall mean the Chase  Manhattan  Bank, or any successor
               trustee appointed as hereinafter provided."

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                                       -2-

     B.   Article II, entitled "Deposit of Securities; Acceptance of Trust",
          shall be amended as follows:

               The  second  sentence  of Section  2.03  Issue of Units  shall be
               amended by deleting the words "on any day on which the  Depositor
               is the only Unit Holder".

     C.   Article III, entitled "Administration of Trust", shall be amended as
          follows:

          (i)  Section 3.01 Initial Costs shall be amended to substitute the
               following language:

               Section 3.01.  Initial Cost The costs of organizing the Trust and
               sale of the Trust  Units  shall,  to the  extent of the  expenses
               reimbursable  to the Depositor  provided  below,  be borne by the
               Unit Holders, provided,  however, that, to the extent all of such
               costs are not borne by Unit Holders, the amount of such costs not
               borne  by Unit  Holders  shall be  borne  by the  Depositor  and,
               provided further,  however, that the liability on the part of the
               Depositor  under this section shall not include any fees or other
               expenses  incurred in connection with the  administration  of the
               Trust subsequent to the deposit referred to in Section 2.01. Upon
               notification  from the Depositor that the primary offering period
               is  concluded,  the Trustee  shall  withdraw  from the Account or
               Accounts specified in the Prospectus or, if no Account is therein
               specified,  from the Principal Account,  and pay to the Depositor
               the Depositor's reimbursable expenses of organizing the Trust and
               sale of the Trust Units in an amount  certified to the Trustee by
               the  Depositor.  If the  balance  of  the  Principal  Account  is
               insufficient  to make such  withdrawal,  the  Trustee  shall,  as
               directed by the  Depositor,  sell  Securities  identified  by the
               Depositor,  or distribute to the  Depositor  Securities  having a
               value,  as  determined  under  Section  4.01  as of the  date  of
               distribution,    sufficient   for   such    reimbursement.    The
               reimbursement  provided  for in  this  section  shall  be for the
               account of the  Unitholders  of record at the  conclusion  of the
               primary  offering  period  and  shall  not  be  reflected  in the
               computation of the Unit Value prior thereto. As used herein, the

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                                -3-

               Depositor's  reimbursable  expenses of  organizing  the Trust and
               sale of the Trust  Units  shall  include  the cost of the initial
               preparation  and  typesetting  of  the  registration   statement,
               prospectuses (including preliminary prospectuses), the indenture,
               and other documents relating to the Trust, SEC and state blue sky
               registration  fees,  the  cost of the  initial  valuation  of the
               portfolio  and audit of the Trust,  the initial fees and expenses
               of the  Trustee,  and  legal  and  other  out-of-pocket  expenses
               related thereto,  but not including the expenses  incurred in the
               printing of preliminary  prospectuses and prospectuses,  expenses
               incurred in the  preparation  and printing of brochures and other
               advertising  materials and any other selling  expenses.  Any cash
               which  the   Depositor   has   identified   as  to  be  used  for
               reimbursement  of  expenses  pursuant  to this  Section  shall be
               reserved by the Trustee for such purpose and shall not be subject
               to distribution or, unless the Depositor otherwise directs,  used
               for  payment  of  redemptions  in excess of the  per-Unit  amount
               allocable to Units  tendered for  redemption.  As directed by the
               Depositor,  the  Trustee  will  advance  funds to the Trust in an
               amount  necessary to  reimburse  the  Depositor  pursuant to this
               Section and shall  recover such advance from the sale or sales of
               Securities at such time as the Depositor shall direct,  but in no
               event later than the  termination of the Trust.  Repayment of any
               such  advance  shall be  secured  by a lien on the  assets of the
               Trust prior to the  interest  of the Unit  Holders as provided in
               Section 6.04.

          (ii) The third paragraph of Section 3.05 Distribution shall be amended
               to add the following sentence at the end thereof:

               "The  Trustee  shall  make a  special  distribution  of the  cash
               balance in the Income and Principal  accounts  available for such
               distribution  to Unit  Holders  of  record  on such  dates as the
               Depositor   shall  direct,   provided   however,   that  no  such
               distribution  shall be made if the assets of the Trust subsequent
               to such  distribution  would not exceed any Deferred Sales Charge
               payable and other trust expenses."

          (iii) The second to the last paragraph of Section 3.08 Sale of
               Securities shall be amended to replace the word "equal" with the
               following phrase: "be sufficient to pay."

<PAGE>

                                -4-

     D.   Reference to United States Trust Company of New York in its capacity
          as Trustee is replaced by the Chase Manhattan Bank throughout the
          Basic Agreement.

                                       Part II.

                         SPECIAL TERMS AND CONDITIONS OF TRUST

     The following special terms and conditions are hereby agreed to:

                  A.    The Trust is denominated National Equity
            Trust, Top Ten Portfolio Series 23.

                  B.    The Units of the Trust shall be subject to
            a deferred sales charge.

                  C. The  contracts  for the  purchase of common stock listed in
            Schedule  A hereto  are those  which,  subject  to the terms of this
            Indenture,  have been or are to be  deposited  in Trust  under  this
            Indenture as of the date hereof.

                  D.    The term "Depositor" shall mean Prudential
            Securities Incorporated.

                  E.    The aggregate number of Units referred to
            in Sections 2.03 and 9.01 of the Basic Agreement is
                     as of the date hereof.

                  F.    A Unit of the Trust is hereby declared
            initially equal to 1/     th of the Trust.

                  G.    The term "First Settlement Date" shall mean
                     , 2000.

                  H.    The terms "Computation Day" and "Record
            Date" shall mean on the tenth day of     2000,     2000,     2000,
            and        2001.

                  I.    The term "Distribution Date" shall be on such mean on
            the twenty-fifth day of       2000,       2000,       2000, and
            2001 or as soon thereafter as possible.

                  J.    The term "Termination Date" shall mean
                     , 2001.

                  K. The  Trustee's  Annual Fee shall be $ (per 1,000 Units) for
            100,000,000 and above units outstanding; $0.80 (per 1,000 Units) for
            50,000,000 - 99,999,999 units  outstanding;  $0.86 (per 1,000 Units)
            for  49,999,999  and below units  outstanding.  In  calculating  the
            Trustee's  annual  fee,  the fee  applicable  to the number of units
            outstanding shall apply to all units outstanding.

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                                       -5-

                  L.    The Depositor's Portfolio supervisory
            service fee shall be $0.25 per 1,000 Units.

                  [Signatures and acknowledgments on separate pages]EXHIBIT 10.7
                                AGREEMENT OF SALE
                                -----------------

     THIS AGREEMENT OF SALE (this "Agreement"), made this 24th day of February,
2000, by and between JONES PANORAMA PROPERTY, INC., a Colorado corporation
(hereinafter called "Seller"), and AMERIVEST BROADWAY PROPERTIES, INC., a
Colorado corporation, (hereinafter called "Buyer").

                              W I T N E S S E T H :

     For and in consideration of the mutual undertakings contained herein and
for other good and valuable consideration, the receipt and sufficiency of which
are hereby mutually acknowledged, the parties hereto, intending to be legally
bound hereby, agree as follows:

     1. Property.

          (a) Seller hereby agrees to sell and convey to Buyer who agrees to
purchase, all that certain lot, piece or parcel of ground (the "Land"), together
with the improvements located thereon (the "Improvements"), situated in Arapahoe
County, Colorado, and known as 9085 E. Mineral Circle, said lot, piece or parcel
being more particularly described on Exhibit "A" attached hereto and made a part
hereof (the Land, the Improvements are collectively referred to as the
"Property").

          (b) The sale set forth in this Agreement shall also include (i) the
fixtures and systems which are located in the Improvements; (ii) all personal
property owned by Seller which is necessary to the operation of the Improvements
and now located in the Improvements; including the backup diesel power
generation system, telecommunications phone jacks, internal wiring and cabling,
and the right to use the name "Panorama Falls" (the "Personal Property"); (iii)
all certificates, licenses, permits, authorizations and approvals issued for or
with respect to the Property by governmental and quasi-governmental authorities
having jurisdiction ("Licenses, Permits and Approvals"), to the extent
transferrable; (iv) all interests, easements, rights, benefits, improvements,
attached fixtures and privileges appurtenant, pertaining or beneficial to the
Land or the Improvements, or both, together with all interests of Seller in
vacated streets and alleys adjacent to the Land ("Contracts"); and (v) all
appurtenances, easements and other rights and privileges in any way pertaining
or beneficial to the Land or the Improvements.

     2. Purchase Price. The total consideration and purchase price (the
"Purchase Price"), which Buyer agrees to pay to Seller and which Seller agrees
to accept for the Property is FIVE MILLION NINE HUNDRED THOUSAND AND 00/100
DOLLARS ($5,900,000.00), payable as follows:

Cash or certified check at
signing of this Agreement
(the "Deposit")                                               $   100,000.00

The Deposit shall be non-refundable
to Buyer at the expiration of the Due
Diligence Period, except as set forth in
paragraph 12(b) hereof.

Cash, certified check or
federally wired funds at
Settlement                                                    $ 5,800,000.00

                        TOTAL                                 $ 5,900,000.00

<PAGE>

     The Deposit shall be paid to the Title Company (as hereinafter defined) and
shall be placed by Title Company in an interest bearing escrow account pending
Settlement (as hereinafter defined). Buyer warrants and represents that Buyer
has completely filled out the form W-9 attached hereto as Exhibit "B" and made a
part hereof and Buyer understands that no interest will be paid on the Deposit
unless and until such form W-9 is completed and delivered to Title Company. All
interest accrued on the Deposit will be paid to Buyer at Settlement or upon the
earlier termination of this Agreement, unless such termination shall be as a
result of Buyer's default, in which event all accrued interest shall be paid to
Seller.

Buyer's Federal Tax I.D. Number  # 84-1314788

Seller's Federal Tax I.D. Number #___________

     3. Evidence of Title: Title.

          (a) Title Commitment. On or before seven (7) days following Seller's
execution of this Agreement (the "Title Deadline"), Seller shall cause to be
furnished to Buyer, at Seller's expense, a current commitment for owner's title
insurance policy issued by Chicago Title of Colorado (the "Title Company") in an
amount equal to the Purchase Price, committing to delete or insure over the
pre-printed standard exceptions (relating to parties in possession, unrecorded
easements, survey matters, any unrecorded mechanic's liens, gap protection (from
the date of commitment through the time of recording the Deed), and unpaid
taxes, assessments and unredeemed tax sales. Seller shall cause the title
insurance policy to be delivered to Buyer as soon as practicable after
Settlement.

          (b) Title Documents. On or before the Title Deadline, Seller shall
cause to be delivered to Buyer copies of all plats, declarations, covenants, and
restrictions burdening the Property and copies of any other documents listed in
the schedule of exceptions to the title commitment ("Exceptions"). The title
commitment referred to in subparagraph 3(a) and the copies of the documents to
be furnished under this subparagraph are referred to as the "Title Documents."

          (c) Title Review. Buyer shall have the right to inspect the Title
Documents. Written notice by Buyer of unmerchantability of title or of any other
unsatisfactory title condition shown by the Title Documents shall be given by
Buyer to Seller at least fifteen (15) days before the Settlement Date. If
written notice of unmerchantability of title or other unsatisfactory title
condition is not given by Buyer to Seller at least fifteen (15) days before the
Settlement Date, then Buyer accepts the condition of title as disclosed by the
Title Documents as satisfactory.

          (d) Matters not of Record. Seller shall deliver to Buyer, on or before
the Title Deadline, true copies of all leases and surveys in Seller's possession
pertaining to the Property and shall disclose to Buyer all easements, liens or
other matters affecting title not shown by the public records of which Seller
has actual knowledge. Written notice by Buyer of any unsatisfactory conditions
affecting title disclosed by Seller or discovered by Buyer and not shown by the

                                       2

<PAGE>

Title Documents shall be given by Buyer to Seller at least fifteen (15) days
before the Settlement Date. If written notice of unsatisfactory conditions
affecting title disclosed by Seller or discovered by Buyer and not shown by the
Title Documents is not given by Buyer to Seller at least fifteen (15) days
before the Settlement Date, then Buyer accepts the condition of title subject to
such rights of third parties of which Buyer has actual knowledge.

          (e) Right to Cure. If Seller receives written notice of
unmerchantability of title or any other unsatisfactory title conditions or
commitment terms as provided in this paragraph 3, then Buyer shall have the
option of either: (i) taking such title as Seller can give, without abatement of
the Purchase Price, or (ii) being repaid all monies paid on account by Buyer to
Seller, including the Deposit, and any interest accrued thereon, and thereafter
there shall be no further liability or obligations by either Seller or Buyer and
this Agreement shall be null and void and of no further effect (except for this
Section 3).

          (f) Survey. Within ten (10) days following Seller's execution of this
Agreement, Seller shall furnish Buyer, at Seller's expense, with a current
survey of the Property prepared to meet the Urban ALTA/ASCM-1970 land title
survey standards, and certified to Buyer, Title Company and Buyer's lender.

     4. Representations and Warranties. Seller represents to the best of its
knowledge, information and belief that at the time of the execution of this
Agreement and as of the date of Settlement:

          (a) There exists no notice of an uncorrected violation of the housing,
building safety or fire ordinances, which has been received by Seller. Seller
will be responsible for the cost of all work, repairs, construction or
installations which may be required or called attention to by any such notice,
issued and/or served after the execution hereof, as well as by any notice issued
and/or served prior to Settlement by any other state, municipal or other
constituted public authority.

          (b) No assessments for public improvements have been made against the
Property which remain unpaid. Seller will be responsible for the payment of any
assessments and charges hereafter made for any public improvements, if work in
connection therewith is begun prior to Settlement.

          (c) It is validly existing and qualified to conduct its business in
the jurisdiction in which the Property is located and to carry on its business
as now being conducted. It has the right, power, legal capacity and authority,
without the approval of any State or Federal regulatory bodies, to enter into
and perform its obligations under this Agreement and the documents to be
executed and delivered pursuant hereto. The execution and delivery of this
Agreement and such documents have been duly and validly authorized by all
necessary action on its part to make this Agreement and such documents valid and
binding upon it.

          (d) The execution and entry into this Agreement, the execution and
delivery of the documents and instruments to be executed and delivered by Seller
on the date of Settlement and the performance by Seller of Seller's duties and
obligations under this Agreement and of all other acts necessary and appropriate
for the full consummation of the purchase and sale of the Property as
contemplated by and provided for in this Agreement, are consistent with and not
in violation of, and will not create any default under, any contract, agreement
or other instrument to which Seller is a party, any judicial order or judgment
of any nature by which Seller or the Property is bound.

          (e) There are no lease options or other rights allowing any tenants to
purchase any portion of the Property.

                                       3

<PAGE>

          (f) Seller has not received any written notices from any governmental
authority that the Property is presently in violation in any respect with any
applicable statutes, ordinances, codes, rules and regulations of any
governmental authority having jurisdiction over the Property ("Laws"). Nor has
Seller received any written notices from any insurance carriers stating that the
Property is not in compliance with any Insurance Regulations or any notice of
cancellation of insurance coverage due to any condition or use of the Property.

          (g) Neither Seller, nor, to the best of Seller's knowledge, any third
party under Seller's control has used, manufactured, stored or disposed of, on,
under or about the Property or transported to or from the Property any flammable
explosives, radioactive materials or wastes, Hazardous Materials or wastes,
toxic materials or wastes, asbestos, asbestos-containing materials or wastes as
defined in the Laws.

          (h) To the best of Seller's knowledge, there are no filed actions,
filed suits or proceedings, or written claims pending, condemnation actions,
which would adversely affect Seller's ability to convey title in accordance with
this Agreement.

          (i) There is no litigation pending or, to the best of Seller's
knowledge, threatened against the Property or against Seller that would have a
material adverse effect on Seller's ability to consummate the transactions
contemplated by this Agreement.

          (j) Seller has not granted any easements or rights-of-way affecting
any or all of the Property, except as shown on the Survey or Title Documents.

          (k) There are no structural defects on any improvement on the
Property. The heating, ventilating and air conditioning systems, electrical,
mechanical and plumbing systems are all in good working order and Seller knows
of no defect to such system.

     5. Settlement.

          (a) Settlement shall be within fifteen (15) days of the expiration of
the Due Diligence Period (as hereinafter defined) but in no event prior to April
1, 2000 ("Settlement Date") at 10:00 a.m. (prevailing time) at the off ice of
the Title Company, unless Seller and Buyer agree in writing to a different time
and place ("Settlement"). The date and time of Settlement is hereby agreed to be
of the essence of this Agreement.

          (b) Real property taxes shall be apportioned on a per diem basis pro
rata as of the date of Settlement on the basis of the most recent levy and
assessment for the Property and shall be readjusted when the final tax bill is
available.

          (c) All utility service charges for electricity, heat and air
conditioning service, other utilities, elevator maintenance, common area
maintenance, other expenses incurred in operating the Property that Seller
customarily pays, and any other costs incurred in the ordinary course of
business or the management and operation of the Property shall be prorated on an
accrual basis. Seller shall pay all such expenses that accrue prior to the date
of Settlement and Buyer shall pay all such expenses accruing on the date of
Settlement and thereafter. Seller and Buyer shall obtain billings and meter
readings as of the date of Settlement to aid in such prorations.

          (d) State and local realty transfer taxes, if any, applicable to the
sale set forth in this Agreement shall be equally divided and half of each paid
by Seller and Buyer.

                                       4

<PAGE>

          (e) Possession of the Property is to be delivered by executed Deed (as
hereinafter defined) and keys to the Property at the time of Settlement. The
Deed shall be prepared by Seller and a copy presented to Buyer at least five (5)
days prior to the Settlement Date.

          (f) Without limitation to other conditions set forth in this
Agreement, and notwithstanding anything contained herein to the contrary,
Buyer's obligation to close hereunder is expressly contingent upon the
satisfaction, or the express written waiver, of the following conditions:

               (i) As of the Settlement, title to the Property shall be as
required by Section 3 of this Agreement;

               (ii) All representations and warranties made by Seller in this
Agreement shall be true, complete and accurate in all material respects as of
the Settlement Date; and

               (iii) Seller shall have performed, observed and complied with all
agreements, covenants and obligations to be performed by Seller under this
Agreement, including without limitation, the execution and/or delivery of all
documents required to be executed and/or delivered by or on behalf of Seller
hereunder.

If the conditions precedent in this Section 5(f) above are not satisfied as of
the Settlement Date, Buyer may exercise any of the remedies set forth in this
Agreement, as applicable, or waive such conditions in whole or in part and
proceed to Settlement.

     6.  Closing Documents.

          (a) At the time and place of Settlement, Seller shall deliver or cause
to be delivered to Buyer the following:

               (i) Seller shall execute and deliver a good and sufficient
general warranty deed to Buyer, conveying the Property free and clear of all
taxes, except the general taxes for the year of the Settlement, and free and
clear of all other liens and encumbrances, including governmental liens for
special improvements installed as of the date of Buyer's execution of this
Agreement, except those Exceptions accepted by Buyer in accordance with
subsection 3(c) of this Agreement, those matters not shown by the public records
disclosed by Seller and accepted by Buyer in accordance with subsection 3(d) of
this Agreement and inclusion of the Property in any special taxing district (the
"Deed");

               (ii) a warranty bill of sale whereby Seller shall convey to Buyer
its title to the Personal Property (the "Bill of Sale");

               (iii) an assignment whereby Seller will assign and Buyer shall
assume all of Seller's right, title, and interest, including all the obligations
of Seller, in, to and under any warranties, Licenses, Permits and Approvals
(hereinafter referred to as the "Assignment");

               (iv) all original Licenses, Permits and Approvals, and as many
signed originals (or true and correct copies of same) of the items covered by
the Assignment as are in Seller's possession, unless previously delivered by
Seller to Buyer;

                                       5

<PAGE>

               (v) all equipment operating manuals and all equipment warranties
and equipment guarantees, if any, in Seller's possession;

               (vi) all master and duplicate keys to all locks for the
Improvements which are in Seller's possession;

               (vii) a non-foreign person certification; and

               (viii) a Seller's title affidavit and such other documents as may
be reasonably requested by the Title Company.

          (b) At the time and place of Settlement, Buyer shall deliver or cause
to be delivered to Seller the following:

               (i) the balance of the Purchase Price;

               (ii) the Assignment; and

               (iii) such other documents as may be reasonably requested by
Seller to carry out the intent of this Agreement or by the Title Insurer.

     7. Risk of Loss. All risk of loss shall be on Seller prior to Settlement.
In the event that there is a casualty or condemnation of all or any portion of
the Property, Buyer may either (i) continue to Settlement without an abatement
in Purchase Price, but Seller will assign any and all rights to Buyer for
insurance or condemnation awards, or (ii) terminate this Agreement in which the
Deposit, plus all accrued interest, shall be delivered to Buyer and this
Agreement shall be null and void and of no force or effect and all copies shall
be canceled.

     8. Recording. This Agreement may not be recorded in the Office for
Recording of Deeds or in any other office or place of public record without
Seller's prior consent.

     9. Seller's Obligations Before Closing.

          (a) From and after the expiration of the Due Diligence Period until
the Settlement Date, Seller will not modify, extend, terminate or otherwise
change any of the terms, covenants or conditions of any leases affecting the
Property, or enter into new leases or any other obligations or agreements
affecting the Property without the prior written consent of Buyer, which consent
may be withheld by Buyer in its sole and absolute discretion.

          (b) Prior to the date of Settlement, Seller shall operate, manage, and
insure the Property in a manner consistent with Seller's historic and customary
practice, shall maintain present services and shall perform when due all of
Seller's obligations under agreements relating to the Property. None of the
Personal Property shall be removed from the Property unless replaced by Personal
Property of equal or greater utility or value.

          (c) From and after the mutual execution hereof, Seller will not make
any material alterations to the Property, unless approved by Buyer.

                                       6

<PAGE>

          (d) Seller shall use commercially reasonable efforts to preserve
intact and unimpaired any and all right-of-way, access, easements, grants,
appurtenances, rights, privileges, leases, contacts, agreements, and licenses in
favor of, relating to, or benefitting all or any portion of the Property.

     10. Intentionally Deleted

     11. Broker. Seller and Buyer acknowledge that Binswanger of Colorado, Inc.,
acting as Seller's agent, and Fuller and Company, acting as Buyer's agent are
the sole, moving, efficient and procuring causes of this sale and in
consideration of its services in making this sale Seller hereby agrees to pay to
Binswanger of Colorado, Inc. and Fuller and Company a commission of four percent
(4%) of the purchase price which shall be shared equally at the time of
Settlement.

     12. Default.

          (a) If Buyer is in default in the observance or performance of its
obligations hereunder, then Seller shall have the right on or before Settlement
to terminate this Agreement and to be paid the Deposit and all interest earned
thereon as liquidated damages for such breach. Upon such termination, Seller and
Buyer shall be released from all further liability and obligations hereunder, it
being understood that Seller's right to terminate this Agreement and to be paid
the Deposit shall be the sole remedy available to Seller in the event of Buyer's
default.

          (b) If Seller is in default in the observance or performance of its
obligations hereunder, then Buyer shall have the right: (i) at Settlement to
terminate this Agreement and to be paid the Deposit and all interest earned
thereon liquidated damages for such breach; or (ii) Buyer may elect to seek
specific performance of this Agreement from Seller. If Buyer elects to terminate
this Agreement, Seller and Buyer shall be released from all further liability
and obligations hereunder.

     13. Notices. All notices to be given to Agent, Seller and/or to Buyer shall
be mailed by registered or certified mail, return receipt requested or an
overnight service with receipt as follows:

                  Seller:                JONES PANORAMA PROPERTY, INC.
                                         1201 Market Street
                                         Suite 2201
                                         Wilmington, DE 19801
                                         Attn: Abram E. Patlove
                                         Fax: 302-658-1600

                  With a copy to:        Comcast Corporation
                                         1500 Market Street
                                         Philadelphia, PA 19102
                                         Attn: General Counsel

                  Agent:                 Binswanger
                                         Two Logan Square
                                         Fourth Floor
                                         Philadelphia, PA 19103
                                         Attn:  Susan M. Sygenda
                                         Fax:  215-448-6274

                                        7

<PAGE>

                  Buyer:                 AMERIVEST BROADWAY PROPERTIES, INC.
                                         c/o Sheridan Realty Advisors, LLC
                                         1800 Glenarm Place, Suite 500
                                         Denver, CO 80202-3871
                                         Attn: John Greenman
                                         Fax: 303-296-7353

                  With a copy to:        Isaacson, Rosenbaum, Woods & Levy, P.C.
                                         633 17th Street, Suite 2200
                                         Denver, CO 80202
                                         Attn: Steven G. Wright, Esq.
                                         Fax: 303-292-3152

     Notices given as provided in this section shall be deemed given on the date
received.

     14. Intentionally Deleted.

     15. Entire Agreement. This Agreement sets forth all the agreements,
promises, warranties, representations, understandings and promises between the
parties hereto, and the parties are not bound by any agreements, undertakings or
conditions except as expressly set forth herein. All additions, variations or
modifications to this Agreement shall be void and ineffective unless in writing
and signed by the parties.

     16. Successors and Assigns; Assignment. This Agreement shall extend to, be
binding upon, and inure to the benefit of the heirs, executors, administrators
and successors of the parties hereto. Buyer shall not assign this Agreement or
any of its rights, duties or obligations hereunder to any other party without
Seller's prior consent.

     17. Governing Law. This Agreement shall be construed and interpreted in
accordance with the laws of the State of Colorado.

     18. FIRPTA. Under Section 1445 of the Internal Revenue Code of 1986 as
amended, and the regulations issued thereunder, Buyer is required to withhold up
to ten percent (10%) of the Purchase Price of the Property unless the Seller
provides Buyer with a "nonforeign certificate" indicating that Seller is not a
foreign person for purposes of the Internal Revenue Code. Agent may be subject
to liability if Seller issues a false "nonforeign certificate". Seller hereby
agrees to indemnify and hold harmless Agent from liability for any tax, penalty,
interest or other charge imposed upon Agent under Seller resulting from the
actions of Seller or Seller's agents.

     19. Due Diligence.

          (a) Within ten (10) days following Seller's execution of this
Agreement, Seller shall deliver to Buyer at Seller's expense the following items
which are in Seller's possession related to the Property:

               (i) Copies of all soil tests, engineering reports and
environmental reports pertaining to the Property;

                                       8

<PAGE>

               (ii) Copies of all leases, if any, including amendments and
modifications thereto, and all other agreements permitting occupancy or use of
the Property;

               (iii) Copies of all current Service Contracts;

               (iv) Copies of any certificates of occupancy, licenses,
engineering reports relating to the Property;

               (v) Copies of all written agreements with third parties,
governmental entities and utility companies, if any, relating to the Property,
and all licenses with respect to the Property or any use of the Property;

               (vi) Copies of all listing agreements and commission agreements
between Seller and brokers or finders for the leasing of all or any portion of
the Property that are currently in effect or obligate Seller or any other owner
to pay a fee or commission hereafter;

               (vii) Copies of expense statements, if any, related to the
operation of the Property;

               (viii) Copies of the ad valorem real and personal property tax
statement pertaining to the Property for the three tax years prior to the date
of Settlement;

               (ix) Copies of any written notices, or other documents pertaining
to the violation or alleged violation of the Laws.

               (x) Itemized inventory of Personal Property.

          (b) From and after the execution of this Agreement by the Seller up to
and including April 1, 2000 (the "Due Diligence Period"), Buyer shall have the
right to enter upon, go in, on or over the Property for the purpose of
conducting building surveys, inspections, soil tests, core drillings,
environmental testing and other examinations thereof as Buyer may desire. Buyer
shall repair any and all damage by reason of any such testing and shall
indemnify and save Seller harmless for any liability in connection therewith. In
the exercise of its rights pursuant to this Section 19, Buyer shall not
interfere with the conduct of Seller's operations being conducted on the
Property and shall give Seller reasonable advance notice of any such activities
Buyer plans to conduct on the Property. If during the Due Diligence Period Buyer
determines, in his sole discretion, that any condition of or relating to the
Property, including, but not limited to, its physical condition, economic
viability or any other factor Buyer deems of concern, is unsatisfactory to
Buyer, Buyer may before the end of the Due Diligence Period terminate this
Agreement by giving Seller written notice of termination and, thereafter, the
Deposit, plus all accrued interest, shall be paid to Buyer and this Agreement
shall become null and void and of no further effect (except for this Section
19).

                                       9
<PAGE>

     20. Lease-Back. Upon Settlement, Buyer agrees to lease to Seller and Seller
agrees to lease from Buyer for a two (2) year period approximately 10,000
rentable square feet of space on an "AS IS" basis within the Improvements at
$20.50 per rentable square foot with a $7.00 per rentable square foot expense
stop (the "Lease"). The Lease shall be in substantially the same form as that
attached hereto as Exhibit "C" and shall be entered into and executed prior to
the expiration of the Due Diligence Period with the commencement date of the
Lease to be the date of Settlement.

     21. Section 1031 Tax-Deferred Exchange. Either Buyer and/or Seller may
substitute a qualified intermediary, as that term is defined in the deferred
like-kind exchanges regulations of the Internal Revenue Code. Each party agrees
to cooperate fully with the party requesting such exchange in order to
facilitate a like-kind exchange of real property, whether simultaneously, a
deferred "Starker" exchange, or any other form of like-kind exchange (as the
requesting party may elect), pursuant to Section 1031 of the Internal Revenue
Code of 1986, as amended, and the regulations promulgated thereunder. The
parties specifically agree to execute such documents and instruments as are
reasonably necessary to effectuate such an exchange, provided that all costs and
expenses associated therewith are borne by the party for whose benefit the
exchange is being made and that Buyer shall not be required to take title to any
property other than the Property. Each party shall be solely responsible for
assuring that the structure its respective proposed exchange is effective for
its individual tax purposes. Furthermore, each party specifically agrees that
either party may assign this Agreement and any of its rights or obligations
hereunder as necessary or appropriate in furtherance of effectuate a Section
1031 like-kind exchange, provided that such assignment shall not serve to
relieve either party of their respective obligations hereunder. The party
requesting the cooperation of the other party shall indemnify, defend and
protect the other party from all costs, expenses and liability associated with
such cooperation.

     IN WITNESS WHEREOF, the individual parties hereto have hereunto duly set
their hands and seals, and the corporate parties hereto have caused these
presents to be duly executed and their corporate seal to be duly attached by
their proper officers thereunto duly authorized, the day and year first above
written.

                                                  SELLER:

ATTEST:                                  JONES PANORAMA PROPERTY, INC.

/s/ Abram E. Patlove                      By:  /s/  Joseph J. Euteneuer
--------------------------                     ---------------------------------
Agent - Comcast                           Title:  Vice President

                                                  BUYER:

ATTEST:                                  AMERIVEST BROADWAY PROPERTIES, INC.

/s/ Charles K. Knight                    By: /s/ James F. Etter
--------------------------                   -----------------------------------
Secretary                                Its:  President

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