N.Y.C. Admin. Code § 28-501.5: § 28-501.5 Construction.

This chapter shall not be construed to grant the right to place or maintain a sign on any building or premises where the placement or maintenance of such sign would otherwise be prohibited pursuant to the zoning resolution, the administrative code or any other provision of law. No permit for a sign issued hereunder shall be deemed to constitute permission or authorization to maintain a sign which is unlawful pursuant to any other provisions of law nor shall any permit issued hereunder constitute a defense in an action or proceeding with respect to such an unlawful sign.