Al, Allegheny may be the oldest. My source was a priest at St. Mary's Parish. My parents wanted to buy plots in the cemetery (during 1960s) and they were unavailable. The priests said that this wouldn't have been a problem if a bishop hadn't sold off the land for Allegheny Cemetery. He didn't think there would be a need for that many graves. I do know that some of the land for Allegheny was bought later (in the 1950s), I think from the Schenleys. My grandparents built a house on Carlton St. in Lawrenceville in the 1920s and the deed says that they bought the land from St. Mary's Cemetery, so I would guess that the cemetery could have been that much bigger, though the wall is above Carlton St. and is probably older than turn of the last century. I checked the History of St. Mary's. The parish was founded in 1853, by Bishop Michael O'Connor, the first bishop of Pittsburgh. From the History "Ground was bought for a church adjoining St. Mary's diocesan cemetery. ... Somewhat in this humble fashion St. Mary's Parish had its beginning close to a cemetery." So the cemetery was there before 1853. Just for interest, " The deed for the St. Mary's property was recorded in Court Nov. 14, 1853. It reveals that 'the said property located in Collins Township was originally owned by Richard Ewart, bought in trust by James and Brigid McCabe in 1849, and the sold to St. Mary's Roman Catholic congregation for church purposes for the sum of $600.'" Rosanne