Grand Theft Auto: London, 1969 is the first expansion pack, to the original Grand Theft Auto. GTA: London 1969 was released in 1999 for the PC and PlayStation. It offered 32 brand new missions, as well as a total of 30 new vehicles, relative to the time period. The game is very similar to the original Grand Theft Auto because it uses the same game engine and is presented in the same format of missions, sections and cutscenes.
Another expansion pack, Grand Theft Auto: London 1961, was later released solely for the PC version and offered as free download from Rockstar. It requires GTA London 1969, which in turn requires GTA 1.