A coordinated landscape plan shall be prepared incorporating the landscape treatment of open spaces, walkways, access roads and parking areas into a cohesive and integrated design. Attractively landscaped open spaces and plazas, designed as gathering places and intended for maximum usability by pedestrians, shall be provided in appropriate locations. All open spaces, pedestrian walkways, parking areas and access drives shall be planned as an integral part of an overall site design, properly related to existing and proposed buildings.