Alcatraz was built between 1910 and 1912 on Alcatraz Island, which is near San Francisco, Calif. During this time, it was a U.S. Army prison, and in 1933, the island was acquired by the U.S. Department of Justice. The building was modernized and, in 1934, became the Alcatraz Federal Penitentiary.
Beginning in 1859, Alcatraz Island housed a citadel, also known as Fort Alcatraz. This functioned as a U.S. Army military defense post and later as a military prison. The prison closed in 1963 due to its high operating expenses. Today, the island is a public museum and is operated by the National Parks Service.