The roots of America's sprawling prison system, which houses over 2.2 million inmates, go back to an idea hatched in Ben Franklin's living room. In a recent story on America's toughest prison – the federal "Supermax" ADX penitentiary in Colorado – the New York Times included an intriguing anecdote: At a salon hosted by Benjamin Franklin, a pamphlet was read calling for the construction of a “house of repentance,” in which solitude could work to soothe the minds of criminals — an enlightened alternative, the group believed, to inhumane “public punishments” like “the gallows, the pillory, the stocks, the whipping post, and the wheelbarrow.” In 1787, a group of Philadelphians, many of whom belonged to the Philadelphia Society for Alleviating the Miseries of Public Prisons, gathered in Benjamin Franklin's living room.