Eastern State Penitentiary - once described as the largest/most expensive prison

Eastern State Penitentiary opened in 1829 and was widely described in its era as one of the largest and most expensive prisons and public works in the United States. Its innovative radial design by John Haviland influenced prison architecture internationally. The site operated as a prison until 1971 and is now a museum and National Historic Landmark offering tours and exhibits documenting its history.