The Elizabeth Arkham Asylum for the Criminally Insane is located on the outskirts of Gotham, housing loonies considered to be legally crazy. Arkham does not have a good record; escapes are frequent (on at least one occasion, an obsessive-compulsive multiple murderer was signed out into the care of an incontinent, alcoholic vagrant, on the grounds that he “looked like a responsible citizen”), and those who are “cured” and released tend to re-offend. Furthermore, several staff members, including at least one director, have ended up as residents, notably Jeremiah Arkham, Harleen Quinzel, and Hugo Strange. In addition, prisoners with unusual medical conditions that prevent them from staying in a regular prison are also incarcerated there. For example, Mr. Freeze is not technically insane, but he requires a strongly refrigerated environment to stay alive, which only Arkham can provide.
Arkham Asylum, by Dan Schoening.