The massive Eastern State Penitentiary in the Fairmount section of Philadelphia, now a National Historic Landmark, is remarkable for its innovative architecture and its pioneering system of isolation in individual cells. Heir to the energetic Quaker reformist tradition in Philadelphia in the 1820s, the penitentiary was a model of idealism in penal reform and a model of prison architecture for the world. About three hundred prisons worldwide trace their paternity to Eastern State Penitentiary. This book shows how the novel experiment in prison reform contended with the realities of the nineteenth and twentieth centuries and explores the legacy of this "crucible of good intentions."