Lot 510, tract 4988, is hereby placed in zone R-4. No building, structure, or improvement, except a fence, gate, wall, or hedge not exceeding three feet (3') in height and not otherwise prohibited by deed or ordinance, shall be erected, constructed, established, altered, or enlarged on said lot within twelve and one-half feet (121/2') of the property line along Tower Drive. (1962 Code § 10-328)