Where the worst of the worst are kept.
Bad guys are kept here. And I mean really bad guys. Villains that have broke the laws of humanity. Also, villains that can be studied are sent here for research. Scientist perform tests on the prisoners daily and even let them try and escape to see where they can improve security. The entire building is a made out of a moon metal that cannot be broken in any way possible. Visiting hours are from 9-7. Security Guards are stationed all around the prison, all guards possess Ferrokinesis and a taser gun.
One hundred years ago, a fifi named Orlatol was being chased by a thief named Ravencroth who happened to be riding a tornado. When he lost him in the city, he decided to build a trap for the thief. So he made a simple cage trap that the thief walked causing the cage to close. Not knowing what to do with him (and there was no prison at the time), he build a prison on an empty plot of land. Little did he know that the land was magical and strengthen building on it making the prison indestructible. He put the thief in and thus founded Ravencroth prison.