General application. All buildings and structures erected hereafter, all uses of land or buildings established hereafter, all structural alterations or relocations of existing buildings occurring hereafter, and all enlargements of, additions to, changes in and relocations of existing uses occurring hereafter shall be subject to all regulations of this chapter which are applicable to the zoning districts in which such buildings, structures, uses or land are located. Existing buildings, structures and uses that do not comply with the regulations of this chapter shall be allowed to continue subject to the provisions of Article XIX of this chapter relating to nonconformities.