Eastern State Penitentiary was built in the 1820s under the Quaker philosophy of reform through solitude and reflection, and has held the likes of Al Capone and Willie Sutton. Covering around 11 acres in Philadelphia, it has become a Historic Site.

Prisons had been pretty widely regarded as failed institutions at the end of the 18th Century, and Eastern State Pen was the new enlightened flagship of the "rehabilitative" approach. Instead of beatings and squalor, and rampant corruption and bribery, this prison would be clean, kind, and incorruptible. From the moment he arrived until the moment he left, the prisoner would see no one. Meals would be delivered through a hole in the wall. Two half-hour exercise sessions outside per day would be allowed in the tiny individual courtyards attached to the 8x12 cells. The furniture of the cell consisted of a mattress and a bible.

Here in this environment, the prisoners would have the chance to escape from the evil influences of social interaction, reflect on their crimes, and return to their natural state of goodness. Additionally, the experience would instill such a dread of future punishment that it would serve as deterrent.

In the end, the solitary confinement of Eastern State ended up driving most of its inmates insane, until 1903 when the idea of complete isolation was abandoned. By the time Eastern State was closed in 1971, it had become just another old, crowded prison with the usual share of brutality, riots, hunger strikes, escapes, suicides, and scandals. Since its closure, Eastern State has become a historical site and a non-profit museum. Every year around Halloweeen they turn Eastern State into a gigantic Haunted House (they call it "Terror Behind the Walls!") which is quite entertaining, though I, personally, find the historical tour to be just as creepy (if not moreso)...
Pictures: http://widefocus.net/ESP_index.html