On-premises
signs or other advertising devices erected before the effective date
of the Historic District Act of 1959 in the Historic Districts of
Nantucket and Siasconset, or before the Historic District Act of 1970
elsewhere, may continue to be maintained, unless any such sign is
enlarged, reworded, redesigned, or altered in any way, including repainting
in a different color. If and when the sign cannot continue to be maintained
pursuant to the foregoing, immediate application must be made for
a certificate of appropriateness for a new sign.