The setting for Terror Behind the Walls is perfect for a haunted attraction. Eastern State Penitentiary was once the most famous and expensive prison in the world, but stands today in ruin, a lost world of crumbling cellblocks and empty guard towers. This gothic structure, with soaring 30-foot high fortress walls, is intimidating enough during the day, and at night, the cellblocks fall into darkness, and the building becomes truly terrifying.