Subdivisions, which include ten (10) or more lots or units, shall be permitted a maximum of two (2) monument signs at each main entrance to the subdivision. No such sign shall exceed twenty-five (25) square feet in outline area per facing, exceed a width of ten (10) feet, nor extend more than ten (10) feet above the elevation of the adjacent street. If a single monument sign is preferred, such representation cannot exceed fifty (50) square feet in total size, while adhering to the same height and width requirements set forth herein. Such signs may be located on any platted lot or common ground of a subdivision and may also be located on any unplatted portion of the subdivision identified as part of a particular development on an approved preliminary subdivision plat or site development plan.