Document:

<PAGE>

                                  EXHIBIT 10.26

                        SECOND AMENDMENT TO AGREEMENT OF
 PURCHASE AND SALE AND ESCROW INSTRUCTIONS BETWEEN THIRD HORIZON GROUP LIMITED
                             PARTNERSHIP ("SELLER")
                  AND TRIPLE NET PROPERTIES, LLC ("PURCHASER")
                     DATED MARCH 24, 2000 (THE "AGREEMENT")

      WHEREAS, Seller and Purchaser have entered into the Agreement for purposes
of the sale and acquisition of certain parcels of improved real property (the
"Real Property") located in various locations throughout the United States and
more particularly described in the Agreement;

      WHEREAS, the original Due Diligence Approval Date, as defined in the
Agreement, was April 23, 2000;

      WHEREAS, the parties have previously executed a First Amendment dated
April 21st, 2000, extending the Due Diligence Approval date through April 26,
2000.

      WHEREAS, Purchaser has not yet completed the necessary due diligence to
determine whether the Real Property is an appropriate investment for Purchaser
and has, therefore, requested an additional extension of the Due Diligence
Approval Date, and, in the event the Purchaser elects to proceed at the extended
Due Diligence Approval Date, the Closing Date.

      NOW, THEREFORE, Seller and Purchaser, for $10.00 and other good and
sufficient consideration, the receipt and sufficiency of which is hereby
acknowledged, agree to the following:

      1. DUE DILIGENCE APPROVAL DATE AND CLOSING DATE. Purchaser and Seller
hereby agree to extend, for all purposes, the Due Diligence Approval Date to the
twenty-first (21st) day following the Effective Date of this Amendment. The
Closing Date shall, subject to further extension in accordance with the
provisions of Section 14.1 of the Agreement, be the thirtieth (30th) day
following such extended Due Diligence Approval Date. The Effective Date of this
Amendment shall be April 25, 2000.

      2. REAL PROPERTY DESCRIPTION. Purchaser and Seller acknowledge and agree
that the description of the Real Property attached to the Agreement is
incomplete in that certain out parcels were inadvertently not included in this
Exhibit. By their execution of this Amendment, Purchaser and Seller agree to
amend the Agreement by attaching a corrected property description as soon as the
correct property descriptions are made available to the parties by the Title
Company and confirmed by the Updated Surveys, at which time the existing Exhibit
A to the Agreement shall be superseded and replaced by the corrected Exhibit A.

      3. SURVEY AND TITLE OBJECTIONS. Purchaser and Seller hereby also extend
Purchaser's period to respond to Seller's response to Purchaser's objections to
Survey and Title until five (5) business days following the later of (i) the
Effective Date and (ii) the date Purchaser receives a written response addressed
to Purchaser from Seller and/or Title Company regarding the Purchaser's
objections including, in the case of any proposed endorsements, the specific
proposed language for such endorsements. In addition, Purchaser and Seller
acknowledge and agree that certain title commitments provided by Seller did not
address all of the Real Property and Purchaser hereby reserves, and is granted,
the right to object to such additional title commitments. The applicable time
periods for such additional title objections, Seller's response to such
objections and Purchaser's response to Seller's response shall be as set forth
in Section 5.1 of the Agreement; provided, however, that the period for
Purchaser's objections shall begin on the later of (i) the Effective Date or
(ii) the date such revised Title Commitments, together with copies of all
applicable Exceptions, are delivered to Purchaser.

      4. MISCELLANEOUS. Any initially captioned terms contained in this
Amendment that are not separately defined herein shall have the meanings
ascribed to them in the Agreement. Except as modified and amended by this
Amendment, all other terms and conditions of the Agreement are hereby
reconfirmed and reaffirmed by Purchaser and Seller.

                                       1
<PAGE>

                           [Signature page to follow]

                                       2
<PAGE>

IN WITNESS WHEREOF, Seller and Purchaser do hereby execute this Second Amendment
as of this 25th day of April, 2000.

SELLER:                                   PURCHASER:

THIRD HORIZON GROUP                       TRIPLE NET PROPERTIES, LLC,
LIMITED PARTNERSHIP,                      a Virginia limited liability company
a Delaware limited partnership

By: THIRD HORIZON HGI, L.L.C.,            By: ________________________________
    a Delaware limited liability              Name:___________________________
    Company, its general partner              Its:____________________________

By: Horizon Group Properties, L.P., a
    ---------------------------------
    Delaware limited partnership,
    its managing member

    By: Horizon Group Properties, Inc.,
        a Maryland corporation, its
        general partner

        By: /s/ Gary J. Skoien
            ---------------------------
            Name:  Gary J. Skoien
                 ----------------------
            Its:   President
                 ----------------------

                                       3<PAGE>

                                  EXHIBIT 10.27

                                 PROMISSORY NOTE

                                                               Chicago, Illinois
$1,500,000.00                                                   April 18, 2000

            FOR VALUE RECEIVED, the undersigned (the "BORROWER") HEREBY PROMISES
TO PAY to the order of Horizon Group Properties, L.P., a Delaware limited
partnership (the "LENDER") the principal sum of $1,500,000.00, together with all
accrued but unpaid interest thereon, on the Maturity Date.

            The Borrower promises to pay interest to the Lender on the
outstanding principal amount hereof from the date hereof until such principal
amount is paid in full.

            1. DEFINED TERMS. As used in this Note:

            "AFFILIATE" means, as to any Person, any other Person that, directly
      or indirectly, controls, is controlled by, or is under common control
      with, such Person.

            "BORROWER" is defined in the introductory paragraph.

            "BUSINESS DAY" means a day (other than a Saturday or Sunday) on
      which banks generally are open in Chicago, Illinois for the conduct of
      substantially all of their commercial lending activities.

            "DEFAULT RATE" is defined in SECTION 2(B).

            "DOLLARS" and the sign "$" each means lawful currency of the United
      States of America.

            "EVENT OF DEFAULT" is defined in SECTION 5.

            "INTEREST RATE" means ten percent (10%) per annum.

            "LENDER" is defined in the introductory paragraph.

            "LOAN" means the term loan made to the Borrower by the Lender which
      is evidenced by this Note.

            "LOAN DOCUMENTS" means, collectively, the Note, any guaranties
      and/or security agreements and other documents entered into by the
      Borrower to evidence or secure the loan evidenced by this Note and all
      documents delivered or required to be delivered by the Borrower pursuant
      thereto.

            "MATURITY DATE" means June 17, 2000.

            "NOTE" means this Promissory Note, as it may be amended or modified
      and in effect from time to time.

            "PERSON" means any natural person, corporation, firm, joint venture,
      partnership, association, enterprise, trust or other entity or
      organization, or any government or political subdivision or any agency,
      department or instrumentality thereof.

                                       1
<PAGE>

            2.    INTEREST AND FEES.

            (a)   INTEREST RATE. Except as otherwise provided in CLAUSE (B) of
                  this SECTION 2, the outstanding principal amount of this Note
                  shall, from the date hereof until such principal amount is
                  paid in full, bear interest at the Interest Rate. Interest on
                  this Note shall accrue and be payable on the Maturity Date or,
                  if earlier, on any date on which the Loan is prepaid, whether
                  by acceleration or otherwise.

            (b)   RATES APPLICABLE AFTER DEFAULT. During the continuance of an
                  Event of Default, the Lender may, at its option, by notice to
                  the Borrower, declare that any amount due and owing hereunder
                  from the Borrower and overdue in respect of the principal
                  amount of the Loan evidenced by this Note shall bear interest
                  at a rate per annum equal to fifteen percent (15%) per annum
                  (the "DEFAULT RATE"). Interest accrued at the Default Rate on
                  the principal amount of this Note shall be payable on demand.
                  If any amount due and payable under this Note is not paid
                  within five (5) Business Days following Borrower's receipt of
                  written demand for such payment, Borrower shall pay to Lender
                  a late charge equal to six percent (6%) of the amount which is
                  due but unpaid.

            (c)   INTEREST BASIS. Interest shall be calculated based on 30-day
                  months for actual days elapsed on the basis of a 365-day year.
                  Interest payable with respect to this Note or any portion
                  hereof which is paid or prepaid shall be payable for the day
                  the Loan is made but not for the day of any payment on the
                  amount paid if payment is received by the Lender prior to 3:00
                  p.m. (Chicago time) at the place of payment.

            (d)   COMMITMENT FEE. In consideration for making the Loan, Lender
                  is entitled to a fee in an amount equal to Thirty Thousand
                  Dollars ($30,000). which fee shall be due and payable on the
                  Maturity Date or such earlier date on which the Loan is repaid
                  in full.

            (e)   SPECIAL FEE. In the event Lender or an affiliate of Lender
                  does not acquire (or does acquire through a forclosure
                  proceeding) either substantially all of the assets and
                  business of Borrower or substantially all of the membership
                  interests in Borrower currently held by The Prime Group, Inc.,
                  on the earlier of (i) the day on which either substantially
                  all of the assets and business of Borrower or substantially
                  all of the membership interests in Borrower currently held by
                  The Prime Group, Inc. is sold, transferred or assigned to an
                  entity which is not affiliated with Lender or The Prime Group,
                  Inc., or (ii) October 31, 2000, Borrower shall pay Lender a
                  fee equal to Ninety Thousand Dollars ($90,000).

            3. REQUIRED PAYMENTS; VOLUNTARY PREPAYMENT.

            (a)   The principal balance of this Note shall be payable by the
                  Borrower on the Maturity Date.

            (b)   The Borrower may from time to time pay, without penalty or
                  premium, the entire outstanding principal amount of this Note
                  or any portion of the outstanding principal amount of this
                  Note upon one Business Day's prior notice to the Lender.

            4. METHOD OF PAYMENT. All payments of principal, interest and other
amounts owing hereunder shall be made, without set off, deduction or
counterclaim, in immediately available funds to the Lender at the Lender's
address at 77 West Wacker Drive, Chicago Illinois 60601, or at any other office
of the Lender specified

                                       2
<PAGE>

in writing by the Lender to the Borrower, by 3:00 p.m. (Chicago time) on the
date when due. Whenever any payment to be made hereunder shall be stated to be
due on a day which is not a Business Day, such payment shall be made on the next
succeeding Business Day, and, in the case of a principal payment, such extension
of time shall in such case be included in computing interest with respect to
such payment.

            5. EVENT OF DEFAULT. If any of the following events (each such
event, an "EVENT OF DEFAULT") shall occur and be continuing:

            (a) Any representation or warranty made, or any financial or other
information provided by the Borrower to the Lender in connection with this Note
or any other Loan Document shall be untrue in any material respect on the date
as of which made;

            (b) The Borrower shall fail to pay any amount of principal on this
Note when due, or the Borrower shall fail to pay any amount of interest on, or
other amount due under, this Note when due ;

            (c) The breach by the Borrower (other than a breach which
constitutes an Event of Default under another clause of this SECTION 5) of any
of the terms or provisions of this Note which is not remedied within fifteen
(15) Business Days after written notice from the Lender.

            (d) The Borrower or any guarantor shall generally not pay its debts
as such debts become due, or shall admit in writing its inability to pay its
debts generally, or shall make a general assignment for the benefit of
creditors; or any proceeding shall be instituted by or against the Borrower or
any guarantor seeking to adjudicate it a bankrupt or insolvent, or seeking
liquidation, winding up, reorganization, arrangement, adjustment, protection,
relief, or composition of it or debts under any law relating to bankruptcy,
insolvency or reorganization or relief of debtors, or seeking the entry of an
order for relief or the appointment of a receiver, trustee, or other similar
official for it or for any substantial part of its property; or

            (e) The occurrence of a default (after the delivery of any required
notice and expiration of all applicable cure periods) under any Loan Document,
then the Lender may declare the principal amount and interest and other amounts
outstanding under this Note owing by the Borrower, to be forthwith due and
payable, whereupon such principal amount, all such interest and all such other
amounts shall become and be forthwith due and payable, without presentment,
demand, protest or notice of any kind by the Lender, all of which are hereby
expressly waived by the Borrower; PROVIDED, HOWEVER, that if an Event of Default
described in clause (d) above occurs with respect to the Borrower, the principal
amount and interest and other amounts outstanding under this Note shall
immediately become due and payable without any election or action on the part of
the Lender. The Borrower shall, as soon as possible, and in any event within
five (5) Business Days after becoming aware of the occurrence of an Event of
Default or an event which, with notice or lapse of time or both, could
constitute an Event of Default, deliver to the Lender a statement setting forth
details of such Event of Default. In addition, Lender may exercise any and all
other rights and remedies available to Lender under any of the other Loan
Documents or otherwise available to Lender at law or in equity.

            6. SET OFF. Upon the occurrence and during the continuance of any
Event of Default, the Lender is hereby authorized at any time and from time to
time, to the fullest extent permitted by law, to set off and apply any and all
deposits (including all account balances, whether provisional or final and
whether or not collected or available) and any other indebtedness and other
obligations at any time held or owing by the Lender to or for the credit or
account of the Borrower against any and all of the obligations of the Borrower
now or hereafter existing under this Note and the Loan Documents executed in
connection herewith, irrespective of whether or not the Lender shall have made
any demand under this Note and although such obligations may be unmatured.

                                       3
<PAGE>

            7. AMENDMENTS. This Note may not be amended orally but only in
writing signed by the Borrower and the Lender.

            8. PRESERVATION OF RIGHTS; SURVIVAL. No delay or omission of the
Lender to exercise any right under this Note shall impair such right or be
construed to be a waiver of any Event of Default or an acquiescence therein. Any
single or partial exercise of any such right shall not preclude other or further
exercise thereof or the exercise of any other right, and no waiver, amendment or
other variation of the terms, conditions or provisions of this Note whatsoever
shall be valid unless in writing signed by the Lender and then only to the
extent in such writing specifically set forth. All remedies contained in the
Loan Documents or available to Lender at law or in equity shall be cumulative
and all shall be available to the Lender until this Note has been paid in full.
All representations and warranties of the Borrower contained in this Note and
any other Loan Document shall survive delivery of this Note and the making of
the Loan evidenced hereby.

            9. HEADINGS; ENTIRE AGREEMENT. Section headings in this Note are for
convenience of reference only, and shall not govern the interpretation of any of
the provisions of this Note. This Note and the Loan Documents embody the entire
agreement and understanding between the Borrower and the Lender and supersede
all prior agreements and understandings between the Borrower and the Lender
relating to the subject matter thereof.

            10. BENEFITS OF THIS AGREEMENT. This Note shall be binding upon the
Borrower and the Borrower's successors and assigns and, subject to the following
sentence, shall not be construed so as to confer any right or benefit upon any
Person other than the Borrower and his or her personal representatives, heirs
and assigns. This Note shall inure to the benefit of the Lender and its
successors and assigns, it being understood that the Lender may from time to
time assign, or grant participations in, its rights hereunder in whole or in
part. The Borrower shall not have the right to assign its rights or obligations
hereunder.

            11. EXPENSES; INDEMNIFICATION. The Borrower agrees to reimburse the
Lender for any costs, internal charges and out-of-pocket expenses (including
reasonable attorneys' fees and time charges and expenses of attorneys for the
Lender, which attorneys may be employees of the Lender) paid or incurred by the
Lender in connection with the preparation, administration, collection or
enforcement of this Note or the other Loan Documents. The Borrower further
agrees to indemnify the Lender, its directors, officers and employees against
all losses, claims, damages, penalties, judgments, liabilities and expenses
(collectively, "INDEMNIFIED OBLIGATIONS") (including, without limitation, all
expenses of litigation or preparation therefor whether or not the Lender is a
party thereto) which any of them may pay or incur arising out of or relating to
this Note, the transactions contemplated hereby or the direct or indirect
application of the proceeds of the Loan evidenced hereby, except that no
indemnified party shall be indemnified for any indemnified obligations to the
extent that they arise from its own gross negligence or willful misconduct as
finally determined by a court of competent jurisdiction. The obligations of the
Borrower under this Section shall survive the repayment of this Note.

            12. SEVERABILITY OF PROVISIONS. Any provision in this Note that is
held to be inoperative, unenforceable, or invalid in any jurisdiction shall, as
to that jurisdiction, be inoperative, unenforceable, or invalid without
affecting the remaining provisions in that jurisdiction or the operation,
enforceability, or validity of that provision in any other jurisdiction, and to
this end the provisions of this Note are declared to be severable. If any
interest payment or other charge or fee payable by the Borrower under this Note
exceeds the maximum amount then permitted by applicable law, the Borrower shall
be obligated to pay, and the Lender shall be entitled to receive, only the
maximum amount permitted by applicable law. If the Lender has collected interest
in excess of such maximum rate, the Borrower's only remedy will be that the
Lender will apply such excess interest as a full or partial prepayment of the
unpaid balance of the principal amount to the extent of the unpaid principal
balance and refund any additional excess amount to the Borrower.

                                       4
<PAGE>

            13. CHOICE OF LAW. THE LOAN DOCUMENTS SHALL BE CONSTRUED IN
ACCORDANCE WITH THE INTERNAL LAWS, WITHOUT REGARD TO CONFLICT OF LAWS
PROVISIONS, OF THE STATE OF ILLINOIS, BUT GIVING EFFECT TO FEDERAL LAWS
APPLICABLE TO NATIONAL BANKS.

            14. CONSENT TO JURISDICTION. THE BORROWER HEREBY IRREVOCABLY SUBMITS
TO THE NON-EXCLUSIVE JURISDICTION OF ANY UNITED STATES FEDERAL OR ILLINOIS STATE
COURT SITTING IN CHICAGO IN ANY ACTION OR PROCEEDING ARISING OUT OF OR RELATING
TO THIS NOTE AND THE BORROWER HEREBY IRREVOCABLY AGREES THAT ALL CLAIMS IN
RESPECT OF SUCH ACTION OR PROCEEDING MAY BE HEARD AND DETERMINED IN ANY SUCH
COURT AND IRREVOCABLY WAIVES ANY OBJECTION IT MAY NOW OR HEREAFTER HAVE AS TO
THE VENUE OF ANY SUCH SUIT, ACTION OR PROCEEDING BROUGHT IN SUCH A COURT OR THAT
SUCH COURT IS AN INCONVENIENT FORUM. NOTHING HEREIN SHALL LIMIT THE RIGHT OF THE
LENDER TO BRING PROCEEDINGS AGAINST THE BORROWER IN THE COURTS OF ANY OTHER
JURISDICTION. ANY JUDICIAL PROCEEDING BY THE BORROWER AGAINST THE LENDER OR ANY
AFFILIATE OF THE LENDER INVOLVING, DIRECTLY OR INDIRECTLY, ANY MATTER IN ANY WAY
ARISING OUT OF, RELATED TO, OR CONNECTED WITH ANY LOAN DOCUMENT SHALL BE BROUGHT
ONLY IN A COURT IN CHICAGO, ILLINOIS.

            15. WAIVER OF JURY TRIAL. THE BORROWER AND, BY ACCEPTANCE HEREOF,
THE LENDER HEREBY WAIVE TRIAL BY JURY IN ANY JUDICIAL PROCEEDING INVOLVING,
DIRECTLY OR INDIRECTLY, ANY MATTER (WHETHER SOUNDING IN TORT, CONTRACT OR
OTHERWISE) IN ANY WAY ARISING OUT OF, RELATED TO, OR CONNECTED WITH THIS NOTE.

            16. Notices. Any notice required or desired to be served, given or
delivered hereunder shall be in writing (including facsimile transmission), and
shall be deemed to have been validly served, given or delivered upon the earlier
of (a) personal delivery to the address set forth below (b) in the case of
mailed notice, two (2) days after deposit in the United States mails, with
proper postage for certified mail, return receipt requested, prepaid, or in the
case of notice by Federal Express or other reputable overnight courier service,
one (1) day after delivery to such courier service, and (c) in the case of
facsimile transmission, upon transmission with confirmation of receipt,
addressed to the party to be notified as follows:

      If to the Borrower:     c/o The Prime Group, Inc.
                              77 West Wacker Drive
                              Suite 4200
                              Attn: Michael W. Reschke
                              Facsimile Number: (312) 917-1511

      With a copies to:       The Prime Group, Inc.
                              77 West Wacker Drive
                              Suite 4200
                              Attn: Robert J. Rudnik, Esq.
                              Facsimile Number: (312) 917-8442

                                       5
<PAGE>

      If to the Lender:       Horizon Group Properties, L.P.
                              77 West Wacker Drive
                              Suite 4200
                              Attention: Gary J. Skoien
                              Facsimile Number:  (312) 917-0911

      With a copy to:         Horizon Group Properties, L.P.
                              77 West Wacker Drive
                              Suite 4200
                              Attention: Richard A. Berman
                              Facsimile Number:  (312) 917-8440

or to such other address as any of the parties may hereafter designate for
itself by written notice to the other parties in the manner herein prescribed.

            17. BORROWER'S WAIVER. Borrower and all endorsers, guarantors and
sureties of this Note and all other persons liable or to become liable on this
Note severally waive presentment for payment, demand, notice of demand and of
dishonor and nonpayment of this Note, notice of intention to accelerate the
maturity of this Note, notice of acceleration, protest and notice of protest,
diligence in collection, and the bringing of suit against any other party, and
agree to all renewals, extensions, modifications, partial payments, releases or
substitutions of security, in whole or in part, with or without notice, before
or after maturity.

                  [Remainder of page intentionally left blank]

                                       6
<PAGE>

            IN WITNESS WHEREOF, the undersigned Borrower has executed this Note
as of the day and year first above written.

                                   BORROWER:

                                   PRIME OUTDOOR GROUP, LLC, a Delaware limited
                                   liability company

                                   By:  /s/ Mark Harris
                                        ---------------------------------------
                                   Its:     President
                                        ---------------------------------------

                                       7

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00009-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00009-of-00352.parquet"}]]