Nothing in this Part shall be construed to require the removal, alteration or change of existing buildings, structures or parts thereof or obstruction not conforming to the regulations as herein set forth. In the event any building, structure or part thereof or obstruction shall violate and/ or exceed the limitations as heretofore set forth and is deemed to be a nonconforming use, the owner or lessee thereof shall permit the installation, operation and maintenance thereon of any marker or light that shall be deemed necessary by the airport authority to indicate to the operators of aircraft in the vicinity of the presence of such building, structure, part thereof or obstruction.