Designed to inspire penitence in evil-doers, Eastern State was open from 1829-1971. Originally, each prisoner had a monastic cell of his own, and his own tiny exercise yard. Every prisoner was supposed to start with two years of solitary. When it was built, it was on the outskirts of Philadelphia. Now the city surrounds it -- it's a mere ten blocks from the Art Museum and looms over its neighborhood as a brooding castle.
In winter, guided tours are the only way to see the place since they can't keep the docents warm enough. Indeed, on a cold rainy day, it was bone-chilling.
The original utopian idea of the penitentiary came to naught. Solitary confinement against one's will, unlike in a monastery, sometimes leads to insanity. More and more prisoners were housed here, and more cells built. Famous inmates include Al Capone and bank-robber Willie Sutton, who managed to escaped.
An extraordinary place to visit. Over three hundred prisons around the world were influenced by this structure (the radial "Philadelphia Plan").
Ghost Cats, an art project. After it was shut down, E.S.P. was left to fall apart. Feral cats moved in and a caretaker fed them. Eventually, they were all rounded up to be spayed/neutered and allowed to live out their lives on the grounds. But they aren't encouraged now.