Gotham City
From Superdickery
Gotham City is a fictional city in the DCU, home to a plethora of crazy people in costumes, such as Batman, The Creeper, Robin, Poison Ivy, Batgirl, and The Joker.
Other characters with Gotham ties include Thriftie, Booster Gold, and Alan Scott.
In addition to a disproportionately high percentage of mass murderers, Gotham has been stricken by disaster after disaster after disaster, to the point that it isn't a wonder that anybody chooses to continue to live there, but rather that there's anybody left alive there at all. Still isn't as bad as Newark, though.