Allegheny Commons is a municipal park located in Pittsburgh's North Side. The park surrounds the neighborhood of Allegheny Center. Dating to 1867, it is the oldest park in the city of Pittsburgh. The park was once free grazing land which surrounded the first 32 blocks of Allegheny City in John Redick's 1784 town plan. It was re-made into a municipal park in the …Allegheny Commons is a municipal park located in Pittsburgh's North Side. The park surrounds the neighborhood of Allegheny Center. Dating to 1867, it is the oldest park in the city of Pittsburgh. The park was once free grazing land which surrounded the first 32 blocks of Allegheny City in John Redick's 1784 town plan. It was re-made into a municipal park in the 1860s by landscape architects hired by Allegheny City.