Originally Posted by majorglory wait, so have other GTAs been based off of real locations as well?

very very loosely.

GTA 3 was very loosely based off locations in NYC and Chicago, GTA VC Miami and parts of Cuba, and GTA SA was (most obviously) based off of Los Angeles, Las Vegas, and San Francisco, with other locations in California scattered about. GTA IV seems to take a more direct approach to emulating NYC, probably much to R*'s criticism.