Originally a coastal fort, Alcatraz Island became a military prison in 1907. The extremely inhospitable waters around the island made it an ideal location for a detention facility, so the armed forces invested in a state-of-the-art concrete cellblock, completed in 1912. In 1933, the U.S. Department of Justice acquired the island and deemed it sufficiently inescapable to house the nation�s most notorious criminals, including Al Capone.
