Cities

Los Santos at sunrise in Grand Theft Auto: Liberty City Stories.

Cities in Grand Theft Auto games are large population centres. Many GTA games (or levels) contain only one city, but GTA San Andreas and GTA IV contain multiple.

Cities of Grand Theft Auto Universe

GTA games are replete with fictional cities, many of which are based on real-life locations:

Liberty State
Liberty City in GTA 1, Liberty City in GTA III Era and Liberty City in GTA IV Era

Liberty City is based on New York City in the GTA 1 Era, GTA III Era and GTA IV Era. Liberty City is the most used city so far, but each are slightly rendered in each game and Era.

Alderney

Alderney is technically a separate state to Liberty City in the GTA IV Era, containing Alderney City (Jersey City and Newark).

United Kingdom
State of Florida
Vice City in GTA 1 and Vice City
San Andreas

San Andreas in GTA 1 is based on San Francisco, while in San Andreas in GTA San Andreas is an entire state comprised of three major cities:

Los Santos

Both Los Santos in GTA San Andreas and Los Santos in the upcoming Grand Theft Auto V are based on Los Angeles.

New Hampshire'

Bullworth is the setting for Bully. It is located somewhere in New England and has various references to the GTA series.

Other