53 Pa. Stat. § 25053
Such regulations shall be made in accordance with a comprehensive plan, and designed to lessen congestion in the streets; to secure safety from fire panic and other dangers; to promote health and the general welfare; to provide adequate light and air; to prevent the overcrowding of land; to avoid undue concentration of population; to facilitate the adequate provision of transportation, water, sewerage, schools, parks and other public requirements. Such regulations shall be made with reasonable consideration, among other things, to the topography and character of the district, with its peculiar suitability for particular uses, and with a view to conserving the value of buildings and encouraging the most appropriate use of land throughout such city.
53 P.S. § 25053