The Damned City is the main setting of Contra: Rogue Corps. It is a mysterious area which arose two years after the Alien Wars had ended, from the grounds where the final battles took place. This ruined city is populated by ruthless fiends that roam the area, but it's also rumored to hold many treasures.
In the opening intro of Contra: Rogue Corps, the Damned City starts rising out from the ground after the government sent in their latest technological weapon, the Vortex Cannon, to wipe out the aliens once and for all. They then send out a special survey team into the city and they discover all sorts of strange artifacts and possibly remnants of technology, all of which originated from an strange dimensional gate at the center of the city. Not only is the source of all those strange technological artifacts but it could also possibly be the source of all the Fiends, hostile yet hideously deformed creatures some of which are fused with cybernetics and machinery. They attacked and killed all humans that dare enter the city or even come into contact with them.