The purpose of communal green areas, spaces artificially created to substitute natural environment, consists primarily for the recreation of the visitors, a result during a temporary stay in contact with this environment. Within these areas, therefore, only permitted constructions are the ones necessary for the accomplishment of the above operation, facilitating the contact with the natural environment, whereas buildings are quite exceptional and may take a minimum percentage of their area. These constructions are not incidental in  the communal green areas and are not intended for performance hence are considered arbitrary and should be demolished.