Abstract: A spacing tool for the construction of gravity wall retaining systems which utilize the mortarless pinned connection of building units containing alignment holes on their upper and lower surfaces. A pair of parallel tines, of circular cross section, are separated by a distance which is determined by the location of the alignment holes on the upper and lower surfaces of building units. A spacing bar is connected to each tine and is formed from the same continuous circular cross-section material as the tines. A U-shaped bracket, having upright members and a lateral member is attached to the spacing bar in a position opposite the tines. A handle is located between the upright members of the bracket and attached thereto.