Alcatraz Island, sometimes referred to as the Rock, is a small island located in the middle of San Francisco Bay in California. It served as a lighthouse, then a military fortification (要塞), then a military prison followed by a federal prison until 1963. It became a national recreation area in 1972. Today, the island is a historic site operated by the National Park Service as part of the Golden Gate National Recreation Area and is open to tourists.
The first Spaniard to discover the island was Juan Manuel de Ayala in 1775, and the earliest recorded owner of the island of Alcatraz is Julian Workman, to whom it was given by Mexican governor Pio Pico in June 1846 with the understanding that the former would build a lighthouse on it. Later that same year John C. Fremont bought the island for $5,000 in the name of the United States government. When California became part of the United States in 1848, the U.S. Army used the island as a military camp for the protection of San Francisco Bay. Later, the army decided to turn it into the site of detention (拘禁), a task for which it was well suited because of its isolation. In 1867 a brick jailhouse was built, and in 1868 Alcatraz was officially designated a long-term detention facility for military prisoners. On March 21, 1907, Alcatraz was officially designated as the Western US Military Prison.
Due to its isolation from the outside by the cold, strong, erous currents of the waters of San Francisco Bay, Alcatraz was used to house Civil War prisoners as early as 1861. In 1898, the Spanish-American war would increase the prison population from 26 to over 450. After the 1906 San Francisco earthquake, civilian prisoners were transferred to Alcatraz for safe confinement. By 1912 there was a large cellhouse, and in the 1920s a large 3-story structure was nearly at full capacity. The island became a federal prison in August 1934. During the 29 years it was in use, the jail held such notable criminals as A1 Capone, Robert Franklin Stroud (the Birdman of Alcatraz), James Bulger and Alvin Karpis, who served more time at Alcatraz than any other inmate. It also provided housing for the Bureau of Prison staff and their families, and no prisoner had ever successfully escaped from the island. The U.S. Army first used Alcatraz Island as ______.