This little stone lay hidden under the ground until 2008, when a landscaper almost literally stumbled on it. It marks the grave of a small child who died in 1794, and that is all we know about her. But the stone and its inscription are very fine for the era, so we suspect her parents had some money. This Post-Gazette article by Ann Rodgers has the story of the stone’s discovery.
Pittsburgh’s earliest settlers are buried downtown in the churchyard of Trinity Cathedral, the Episcopal cathedral of Pittsburgh (or at least the cathedral of some Anglican diocese, though which one may be up in the air right now). Next door is First Presbyterian, another colonial-era congregation, and across the street is the Duquesne Club, forming a perfect triangle of old money.
Trinity Churchyard is half a block up Sixth Avenue from the Wood Street subway station.