School Street is essentially the path of I279 into the North Shore now.
The history is confusing. The Pirates organization played in "Exposition Park (I)" during the 1882 season. I've never seen any photos or field dimensions. The site is purportedly exactly where Three Rivers Stadium was built. Because of flooding and fires, a field next door was hastily constructed.
"Exposition Park (II)" was built immediately to the east and known as the "upper field" because though it was closer to the river, the elevation was higher. The Pirates started the 1883 season there, but quickly abandoned it due to flooding and returned to Expo I. Expo II site eventually became a parking lot for Three Rivers. They moved to Recreation Park for the 1884 season.
"Exposition Park (III)" was raised on the same site as Expo II. A Players League team opened the park, but folded after that 1890 season. The Pirates moved there for the 1891 season.
Some day, I may finish my version of Expo (III). But in the meantime, enjoy this interpretation a user created for MLB the Show:
https://www.reddit.com/r/mlbtheshows...burgh_pa_xbox/