Parking structures, whether freestanding or integral with other uses in the same building, shall have another permitted first floor use on any portion of the structure visible from any streets, required pathways, or riverfront access or suitable architectural treatment shall be provided. For any parking structures, whether freestanding or integral with other uses in the same building, which contain three or more parking levels, another permitted first floor use on any portion of the structure visible from any streets, required pathways, or riverfront access, shall be mandatory, if the first floor is out of the floodplain. If the first floor is within the floodplain, suitable architectural treatment shall be provided. Any additional floors of exposed parking structures shall also have suitable architectural treatment.