(1) No person shall erect or maintain any sign, as defined in § 14-1901 within one hundred fifty feet of the boundaries of Washington square which is visible from any point within the boundaries of Washington square unless a permit to do so has first been obtained from the Department of Licenses and Inspections;

(2) No permit to erect or maintain any sign within one hundred fifty feet of the boundaries of Washington square which is visible from any point within the boundaries of Washington square shall be granted unless the sign for which such permit is sought has been approved by the Art Commission;

(3) When sign controls on any building, structure or upon any land located within one hundred fifty feet of the boundaries of Washington square are more restrictive through other provisions of this Title, this Section shall not be interpreted as superseding those provisions;

(4) The provisions of § 14-2006.1(1) shall not apply to any sign permanently and lawfully in existence on the effective date of the enactment of this Section.