Planned unit development of land may be permitted to provide means for effectuating a more desirable physical development pattern than would be possible through the strict application of the requirements of the Subdivision Regulations or the Zoning Code. A certain flexibility in the design of a project should be permitted by the City to encourage the subdivider to adjust streets to irregular topography; to economize in the construction of utilities; and, among other things, to create architectural variations in the development as well as attractive and usable buildings and building sites. Such development shall be designed so as to enhance the community in general by providing amenities which are unique to the area.