In the 80s (after Rocky III), it was at the top of the Museum steps for years.To be clear - the museum doesn't actually have a Rocky statue anywhere right? That's what I remember from my Philly visit, but that was like 20 years ago.
Then outside The Spectrum (now demolished) way back in the day 90s, 00's. It was moved into storage for a few years, moved back briefly to the top of the Art Museum steps for the movie "Rocky Balboa" then finally ended up where it is now.