I remember walking through Philly and seeing these in the 90s or early 2000s. They were very distinctive and kind of a local landmark
https://toynbeeidea.com/where2-2/ has a map of a lot of them. All the originals are long gone and only a handful remain. I would suspect at least a few that remain are possibly copycats given they came about many years later, look kind of different, some came about very far away, and the whole thing has been popularized quite a bit over the past 15ish years (there’s literally a documentary on it). The documentary maker had a pretty credible theory on who did it too iirc but I don’t remember the details