CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

     We have issued our report dated April 22, 2008, accompanying the financial
statements of California Insured Municipals Income Trust, Series 241, Colorado
Insured Municipals Income Trust, Series 101 and Virginia Investors' Quality
Tax-Exempt Trust, Series 100 (included in Van Kampen Unit Trusts, Municipal
Series 593) as of December 31, 2007, and for each of the two years in the period
ended and the financial highlights for the period from January 18, 2006 (date of
deposit) through December 31, 2006 and for the year ended December 31, 2007,
contained in this Post-Effective Amendment No. 2 to Form S-6 (File No.
333-129793) and Prospectus.

     We hereby consent to the use of the aforementioned report in this
Post-Effective Amendment and Prospectus and to the use of our name as it appears
under the caption "Other Matters-Independent Registered Public Accounting Firm".

                                                  GRANT THORNTON LLP

New York, New York
April 22, 2008