The setting of "City of Heroes" was the fictional Paragon City, located in Rhode Island in the United States. The city was divided into several smaller neighborhoods that had varying enemies and progressively higher levels of enemies within them. The arbitrary divisions between zones are explained in game by the presence of "War Walls", powerful force fields derived from alien technology which were used to defend various areas of the city. Heroes set out by dealing with low-powered street gangs in the initial zones, working their way up to fighting increasingly dangerous threats — such as organized crime, corrupt corporations, hostile aliens, and supernatural terrors — even eventually entering other dimensions to fight supremely powerful enemies.