Mega City, formerly known as Monstropolis, is a hi-tech city with flying cars and other advanced technology. Dr. Light greatly contributed to the city with his inventions, such as the "Light Perfected Traffic Control System", "Light Automatic Traffic Speed Governor", and "Light Perfected Air-traffic Control System". Dr. Light's systems are attacked by robots, and Dr. Light discovers that the responsible for sabotaging his municipal inventions was his former partner, "Dr. Wiley" (Dr. Wily).
A small part of the city ended up damaged by Break Man during Mega Man's birthday, although it ended up restored after the Genesis Wave affecting Earth 20XX was removed via Chaos Control. However, the city, alongside the world, ended up undergoing severe damage after Ra Moon started frying everything electronic.
During the Worlds Collide arc, the Roboticized Masters robbed the city's first national bank, with Proto Man and later Mega Man trying to halt the robbery. Mega Man later returned to Mega City itself during a fight with Sonic the Hedgehog, where he used the territory to his advantage against the blue hedgehog, although they later called a truce when Tails Man ambushed them on Doctor Eggman and Wily's orders.