53 Pa. Stat. § 1673
Every municipality shall have power, by ordinance, to locate streets and alleys, and to include therein streets and alleys, or parts thereof, theretofore opened or used for highway purposes; and to locate streets or alleys, theretofore opened or used for highway purposes, of a greater width, and to include therein such streets or alleys, or parts thereof; and to revise the lines of such streets or alleys in accordance therewith, and to place the same on the general plan of the streets and alleys of such municipality of such greater width. All subdivisions of property thereafter made shall conform thereto. No such location shall be construed to authorize the entry upon, taking, or appropriation of any property, within such located street or alley, not theretofore opened or used for highway purposes; nor shall the same interfere in any way with the rights of the owners to the full use and enjoyment of such property, except that, whenever thereafter such located street or alley shall be ordered to be opened, widened, extended, or straightened according to such location, buildings erected upon property within the lines of such located streets or alleys after such location was made, shall be removed at the expense of the owner, and without any liability therefor to such municipality.
53 P.S. § 1673