No blank walls. All facades or sides of buildings facing the street shall have a decor that prohibits, for a maximum distance of 15 feet horizontally, bare unadorned walls along each floor. These walls shall have appurtenances either decorative or functional to satisfy the condition. Such appurtenances shall consist of windows, doors, columns, lintels, cornices, balconies, overhangs, awnings, arches, railings or any other architectural items that fit the herein recommended design theme.