It is also believed to have been the spot on which the first religious service of any kind offered west of the Allegheny Mountains was held.

On July 1, 1754, French troops on their way to capture Fort Necessity from the British climbed the bank from the Monongahela River with their Chaplain Rev.

The Catholic Irish settlers decided to build a church the same as other religious groups in the area.

At the time, Brownsville was an important gateway to the West and South due to its location on the National Road,[4] and believing it, not Pittsburgh, would become the seat of the episcopal see, the founders built the church to be a future cathedral.

The pulpit is located to the left of the altar, as in a cathedral, and the crypt includes space for the tombs of bishops.