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                                                                       Exhibit 5

                   [Letterhead of Cravath, Swaine & Moore LLP]

                                                                   July 16, 2003

                        Crown Castle International Corp.
                        --------------------------------
                        15,597,783 Shares of Common Stock
                        ---------------------------------

Ladies and Gentlemen:

         We have acted as counsel for Crown Castle International Corp., a
Delaware corporation (the "Company"), in connection with the filing by the
Company with the Securities and Exchange Commission (the "Commission") of a
registration statement on Form S-3 (the "Registration Statement") relating to
resales of 15,597,783 shares of common stock, par value $.01 per share, of the
Company (the "Common Stock") by certain securityholders named under the heading
"Selling Securityholders" in the prospectus that forms part of the Registration
Statement or in a supplement thereto. The Common Stock being registered under
the Registration Statement will be offered on a continued or delayed basis
pursuant to the provisions of Rule 415 under the Securities Act of 1933, as
amended.

         In that connection, we have examined originals, or copies certified or
otherwise identified to our satisfaction, of such documents, corporate records
and other instruments as we have deemed necessary for the purposes of this
opinion, including the following: (a) the Restated Certificate of Incorporation
of the Company, (b) the Amended and Restated By-

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laws of the Company and (c) certain resolutions adopted by the Board of
Directors of the Company.

         Based on the foregoing, we are of the opinion as follows:

         1. The Company has been duly incorporated and is a validly existing
corporation under the laws of the State of Delaware.

         2. The shares of Common Stock are validly issued, fully paid and
nonassessable.

         We are admitted to practice in the State of New York, and we express no
opinion as to any matters governed by any law other than the law of the State of
New York, the General Corporation Law of the State of Delaware and the Federal
law of the United States of America.

         We are aware that we are referred to under the heading "Validity of
Securities" in the prospectus forming part of the Registration Statement, and we
hereby consent to such use of our name therein and the filing of this opinion as
Exhibit 5 thereto. In giving this consent, we do not hereby admit that we are
within the category of persons whose consent is required under Section 7 of the
Securities Act or the Rules and Regulations of the Commission promulgated
thereunder.

                                               Very truly yours,


                                               /s/ Cravath, Swaine & Moore LLP


Crown Castle International Corp.
  510 Bering Drive, Suite 500
    Houston, Texas 77057-1457



