Although Catholic religious services in Merriam Park date back to 1877, when diocesan priests provided sacraments for families and religious brothers of the Franciscan Third Order (who operated a school there), a more permanent church presence separate from the local seminary was still needed in Merriam Park.

Father Hart would later serve as a chaplain with the US Army in World War I, where he would be mentioned in dispatches for heroism in the Meuse-Argonne Offensive.

Work eventually went to the Pittsburgh-based architect John T. Comes, who created a design based on a pared-down English Gothic style.

Atop the east narthex doors, a statue of the titular evangelist Saint Mark rests on a pediment above the entrance.

A predominantly notable feature of the exterior is its unique six-sided, sharp needle-like spire that rises up from the towered steeple over the sanctuary end of the church, topped with an oxidized copper cross.

The main sanctuary of the church is notable for its large ornate reredos altarpiece of dark-stained wood, with various gilt carved trim motifs and featuring panels of various saints.