{"nrhp_refnum":"76000209","name":"Alcatraz","other_names":["Alcatraz Island National Historic Landmark","Pacific Branch, U"],"category":"district","location":{"address":"Alcatraz Island, San Francisco Bay","address_restricted":false,"city":"San Francisco","county":"San Francisco","state":"CA","lat":37.82684043350005,"lon":-122.42310153607019,"geom_source":"nps_gis"},"listed_date":"1976-06-23","is_nhl":true,"nhl_designated_date":"1986-01-17","areas_of_significance":["Commerce","Military","Engineering","Social History"],"significance_levels":["national"],"summary":{"what_it_is":"Alcatraz is a rocky island in San Francisco Bay, California, roughly a half mile long, developed from 1853 as an Army fortress, then used as a military prison and later as a federal penitentiary. The nominated district covers about 12.5 acres, including the island and surrounding waters.","why_significant":"The nomination argues for national significance in military history and social history (penology). In the mid-19th century the island was a fortress guarding the entrance to the Bay and had a brick Citadel designed for defense by rifle fire alone. It later became a military prison and then one of America's most famous federal penitentiaries, holding convicts considered too unmanageable for other prisons.","narrative":"Alcatraz is a rocky island in San Francisco Bay, about a half mile long and 140 feet high. Acquired by the United States in 1848, it was fortified from 1853 with batteries, casemates, a sally port and a brick Citadel protected by a dry moat. The Citadel was designed to be defended entirely by rifle fire. The fortress never fired a shot in anger, but it served as a deterrent during the Civil War. Its remote setting and cold, swift waters also made it a natural prison. It became a military prison, was formally designated one in 1907, and from 1934 to 1963 was a maximum-security federal penitentiary for the most unmanageable convicts, including Robert Stroud and Al Capone. The 1969 to 1971 Indian occupation left several buildings burned and others vandalized. Salt air has since caused serious decay. Since 1972 the island has been part of Golden Gate National Recreation Area, open for tours.","period_of_significance":"1853-1971","architect_builder":"U.S. Army, U.S. Bureau of Prisons","architectural_style":null,"criteria":[],"status_note":"Altered and largely deteriorated; the prison closed in 1963, buildings were burned and vandalized during the 1969-1971 Indian occupation, and the island has been part of Golden Gate National Recreation Area with public tours since 1972.","vacant_flag":null,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:55:32.255992-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_CA/76000209.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/76000209/ae8ef602b2-800.webp","url_1600":"https://nationalhistoricalregister.com/media/76000209/ae8ef602b2-1600.webp","licence":"CC BY-SA 4.0","author":"Frank Schulenburg","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Alcatraz_Island_as_seen_from_the_East.jpg\" rel=\"noopener\">Frank Schulenburg</a>, <a href=\"https://creativecommons.org/licenses/by-sa/4.0\" rel=\"license noopener\">CC BY-SA 4.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Alcatraz_Island_as_seen_from_the_East.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/123861025","wikipedia":"https://en.wikipedia.org/wiki/Alcatraz_Island","wikidata":"https://www.wikidata.org/wiki/Q131354"},"indexable":true,"url":"https://nationalhistoricalregister.com/california/san-francisco/alcatraz-76000209/"}