Alcatraz is infamous as one of America’s prisons for the worst of the worst criminals. The prison was originally fortified as a United States military stronghold and held prisoners seized from the Confederate Army in the nineteenth century. The island is surrounded by the freezing, strong currents of the of the San Francisco Bay, making it ideal for trapping prisoners of war. However, the island is most famous for its eventual phase as a federal penitentiary for dangerous criminals, including Al Capone and George “Machine Gun” Kelly. Only three of the thousands of prisoners ever escaped.