Exhibit 4.1




                          SECOND SUPPLEMENTAL INDENTURE

         SECOND SUPPLEMENTAL  INDENTURE (this "Second Supplemental  Indenture"),
dated  as of June 6,  2000,  between  SpectraSite  Holdings,  Inc.,  a  Delaware
corporation  (the  "Issuer"),  and United  States  Trust  Company of New York, a
national banking association, as trustee (the "Trustee").
                                   WITNESSETH:

         WHEREAS, the Issuer and the Trustee entered into an Indenture, dated as
of June 26, 1998 (the  "Original  Indenture"),  with respect to the Issuer's 12%
Senior Discount Notes Due 2008 (the "2008 Notes"),  which Original Indenture was
amended pursuant to a First Supplemental  Indenture,  dated as of March 25, 1999
(the Original Indenture, as so amended, the "1998 Indenture");

         WHEREAS,  the  Issuer  desires  to amend  the  "Permitted  Investments"
definition and Section 4.8 (Limitations on Transactions  with Affiliates) of the
Indenture in certain respects;

         WHEREAS,  in order to effect such amendments,  the Issuer has solicited
consents  from the  Holders  of the 2008  Notes  through a Consent  Solicitation
Statement,  dated as of May 11, 2000, as amended by a Supplement,  dated June 1,
2000, to certain  amendments to the 1998 Indenture (the "Proposed  Amendments"),
which Proposed Amendments are reflected in this Second Supplemental Indenture;

         WHEREAS,  in  accordance  with Section 9.2 of the 1998  Indenture,  the
Issuer has  received  written  consent of the  Holders of at least a majority in
principal  amount at  maturity  of the 2008 Notes  outstanding  to the  Proposed
Amendments;

         WHEREAS,   all  things  necessary  to  make  this  Second  Supplemental
Indenture a valid  supplement to the 1998  Indenture  according to its terms and
the terms of the 1998 Indenture have been done;

         NOW, THEREFORE, the parties hereto agree as follows:

         SECTION 1. Certain Terms Defined in the 1998 Indenture. All capitalized
terms used herein without definition shall have the meanings ascribed thereto in
the 1998 Indenture.

         SECTION 2.  Amendments to the 1998 Indenture.  The 1998 Indenture is
                     ---------------------------------
hereby amended as follows:


         (a) The following  definition  in Section 1.1 of the 1998  Indenture is
amended and restated in its entirety as follows:

                           "Permitted  Investment"  means an  Investment  by the
                  Issuer  or any  Restricted  Subsidiary  in (i) the  Issuer,  a
                  Wholly  Owned  Subsidiary  or a Person

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     which  will,  upon the  making of such  Investment,  become a Wholly  Owned
     Subsidiary;  provided, however, that a loan or other extension of credit by
     the Issuer or a Restricted  Subsidiary to a Restricted  Subsidiary  that is
     not  a  Wholly  Owned   Subsidiary   also  will   constitute  a  "Permitted
     Investment";  and provided further,  however,  that a Permitted Business is
     the primary  business of the Person in which any such  Investment  is made;
     (ii) another Person if as a result of such  Investment such other Person is
     merged  or  consolidated  with or into,  or  transfers  or  conveys  all or
     substantially  all its assets to,  the Issuer or a  Restricted  Subsidiary;
     provided,  however,  that such  Person's  primary  business  is a Permitted
     Business;  (iii) Temporary Cash Investments;  (iv) receivables owing to the
     Issuer or any Restricted Subsidiary, if created or acquired in the ordinary
     course  of  business  and  payable  or  dischargeable  in  accordance  with
     customary trade terms; provided, however, that such trade terms may include
     such  concessionary  trade  terms  as the  Issuer  or any  such  Restricted
     Subsidiary deems reasonable under the  circumstances;  (v) payroll,  travel
     and similar advances to cover matters that are expected at the time of such
     advances  ultimately to be treated as expenses for accounting  purposes and
     that are made in the ordinary course of business; (vi) loans or advances to
     employees  made in the  ordinary  course of business  consistent  with past
     practice of the Issuer or such Restricted Subsidiary,  but in any event not
     to exceed $2.0 million in the aggregate  outstanding at any one time; (vii)
     stock, obligations or securities received in settlement of debts created in
     the ordinary  course of business and owing to the Issuer or any  Restricted
     Subsidiary or in satisfaction of judgments; (viii) any Person to the extent
     such  investment  represents  the  non-cash  portion  of the  consideration
     received for an Asset  Disposition  as  permitted  pursuant to Section 4.7;
     (ix) Capital Stock of the Issuer or any  Restricted  Subsidiary  purchased,
     redeemed or  otherwise  acquired  or retired for value from  members of the
     Issuer's  management or employees,  but in any event not to exceed $500,000
     in aggregate in any twelve-month period; (x) other Investments in Permitted
     Businesses not to exceed, at any one time outstanding (each such Investment
     being  measured as of the date made and without giving effect to subsequent
     changes in value),  the sum of (x) $60.0  million  and 10% of the  Issuer's
     Consolidated  Tangible Assets; (xi) any Interest Rate Agreement or Currency
     Agreement;  (xii) any  acquisition  of assets  solely in  exchange  for the
     issuance of Capital  Stock (other than  Disqualified  Stock) of the Issuer;
     (xiii) prepaid  expenses,  negotiable  instruments  held for collection and
     lease,  utility and workers'  compensation,  performance  and other similar
     deposits;  (xiv)  deposits  of proceeds or  Qualified  Proceeds  from Asset
     Dispositions  with  a  "qualified  intermediary,"  "qualified  trustee"  or
     similar person for purposes of facilitating a "like-kind"  exchange made in
     accordance with the applicable  provisions of the Internal  Revenue Code of
     1986,  as  amended;  provided,  however,  that the making of any  Permitted
     Investment  pursuant  to this clause  (xiv) will not in any manner  violate
     Section  4.7;  (xv)  Investments  in an amount  not to exceed  the Net Cash
     Proceeds or  Qualified  Proceeds of the  issuance or sale,  other than to a
     Subsidiary  of the  Issuer,  of  Capital  Stock of the  Issuer,  other than
     Disqualified  Stock,  since June 1, 2000,  to the extent that such Net Cash
     Proceeds or Qualified  Proceeds  have not been applied to make a Restricted
     Payment or to effect other transactions

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     pursuant  to  Section  4.5 or to the  extent  such  Net  Cash  Proceeds  or
     Qualified  Proceeds  have not been  used to Incur  Indebtedness;  and (xvi)
     other  Investments  not to  exceed,  at any  one  time  outstanding,  $75.0
     million.  The amount of any  Investment  shall be measured on the date made
     and shall not give effect to subsequent changes in value.

         (b) Section  4.8(b) of the 1998 Indenture is amended in its entirety to
read as follows:


                  (b) The  provisions of paragraph (a) of this Section 4.8 shall
         not prohibit (i) any Restricted  Payment  permitted to be made pursuant
         to Section 4.5,  (ii) any issuance of  securities,  or other  payments,
         awards or grants in cash,  securities or otherwise  pursuant to, or the
         funding of, employment arrangements,  stock options and stock ownership
         plans approved by the Board of Directors,  or any arrangements relating
         thereto,  (iii)  the  grant of  stock  options  or  similar  rights  to
         employees and directors of the Issuer pursuant to plans approved by the
         Board of Directors, (iv) loans or advances to employees in the ordinary
         course of business in accordance  with the past practices of the Issuer
         or its  Restricted  Subsidiaries,  but in any event not to exceed  $1.0
         million in the aggregate  outstanding  at any one time, (v) the payment
         of  reasonable  fees to  directors  of the  Issuer  and its  Restricted
         Subsidiaries  who are not  employees  of the  Issuer or its  Restricted
         Subsidiaries,  (vi) any transaction between the Issuer and a Restricted
         Subsidiary or between  Restricted  Subsidiaries,  (vii) the issuance or
         sale of any  Capital  Stock  (other  than  Disqualified  Stock)  of the
         Issuer, (viii) any transaction consummated pursuant to the terms of any
         agreement  described in the Offering  Circular to which the Issuer is a
         party,  in each case as such  agreement  is in effect on the Issue Date
         and   without   giving  any  effect  to  any   subsequent   amendments,
         modifications  or  alterations   thereof,   (ix)  any  transaction  (A)
         contemplated  by the Nextel Merger  Agreement,  (B)  contemplated  by a
         credit facility on substantially  the terms set forth in the Commitment
         Letter  dated  January  15,  1999,  as  amended,   between  SpectraSite
         Communications,  Inc., as the borrower,  and Canadian  Imperial Bank of
         Commerce,  CIBC  Oppenheimer  Corp.  and  Credit  Suisse  First  Boston
         Corporation, pursuant to which any Affiliate of the Issuer is a lender,
         provided that the terms and conditions of such credit  facility,  taken
         as whole, are no less favorable to the Restricted  Subsidiary that is a
         party  thereto  than those that could be  obtained  at the time of such
         transaction in  arm's-length  dealings with a Person who is not such an
         Affiliate or (C) between the Issuer or any  Restricted  Subsidiary  and
         any  Affiliate  of the  Issuer  involving  ordinary  course  investment
         banking,   commercial  banking  or  related  activities,  and  (x)  any
         transaction  in the ordinary  course of business  between the Issuer or
         any  Restricted  Subsidiary  and  Nextel  (or any of its  Subsidiaries)
         relating to the purchase of Nextel (or its Subsidiaries)  Tower Assets,
         provided,  however,  that such transaction is on terms that are no less
         favorable,  taken as a whole, to the Issuer or the relevant  Restricted
         Subsidiary  than those that could have been  obtained  in a  comparable
         transaction  by the  Issuer  or  such  Restricted  Subsidiary  with  an
         unrelated  Person or is otherwise on terms that,  taken as a whole, the
         Issuer  has  determined  to be  fair  to the  Issuer  or  the  relevant
         Restricted Subsidiary, and provided,  further, that no such transaction
         shall involve an aggregate amount in excess of $15.0 million.

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         SECTION 3.  Governing Law.  The laws of the State of New York shall
govern this Second Supplemental Indenture (without regard to the choice of law
provisions thereof).

         SECTION 4.  Counterparts.  This Second  Supplemental  Indenture  may be
signed in any number of counterparts,  each of which shall be an original,  with
the same  effect as if the  signatures  thereto  and  hereto  were upon the same
instrument.

         SECTION 5.  Ratification.  Except as  expressly  amended  hereby,  each
provision of the 1998 Indenture  shall remain in full force and effect,  and, as
amended  hereby,  the 1998 Indenture is in all respects  agreed to, ratified and
confirmed by each of the Issuer and the Trustee.

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<PAGE>



         IN  WITNESS  WHEREOF,  the  parties  hereto  have  caused  this  Second
Supplemental Indenture to be duly executed as of the date first above written.


                                              SPECTRASITE HOLDINGS, INC.

                                              By:  /s/ Stephen H. Clark
                                                  ---------------------------

                                             Name:  Stephen H. Clark
                                                   -------------------------
                                             Title:  Chief Executive Officer
                                                   -------------------------


                                             UNITED STATES TRUST COMPANY OF NEW
                                              YORK, as Trustee

                                              By:  /s/ Margaret M. Ciesmelewski
                                                    ----------------------------

                                             Name:  Margaret M. Ciesmelewski
                                                    ---------------------------
                                             Title:  Assistant Vice President
                                                    ---------------------------