The strong currents around the island and cold water temperatures made escape nearly impossible, and the prison became one of the most notorious in American history.

Alcatraz Island is the site of the abandoned federal prison, the oldest operating lighthouse on the West Coast of the United States, early military fortifications, and natural features such as rock pools and a seabird colony (mostly western gulls, cormorants, and egrets).

Later in 1846, acting in his capacity as military governor of California, John C. Frémont bought the island for $5,000 in the name of the United States government from Francis Temple.

Tower, the United States Army Corps of Engineers began fortifying the island, work which continued until 1858, when the initial version of Fort Alcatraz was complete.

At this time, it also served as the San Francisco Arsenal for storage of firearms to prevent them falling into the hands of Confederate sympathizers.

During the war, Fort Alcatraz was used to imprison Confederate sympathizers and privateers on the west coast, but its guns were never fired at an enemy.

In 2019 "Binghamton University archaeologist Timothy de Smet and colleagues located historical remains beneath the former recreation yard of the Alcatraz Federal Penitentiary."

Using ground-penetrating radar (GPR) data and georectifications, Smet and colleagues discovered structures, including "a 'bombproof' earthwork traverse along with its underlying vaulted brick masonry tunnel and ventilation ducts," in surprisingly good condition.

[21][22] Because of the isolation created by the cold, strong currents of the waters of San Francisco Bay, as early as 1859, Alcatraz was used to house soldiers convicted of crimes.

[citation needed] Starting in 1863, the military also held private citizens accused of treason, after the writ of habeas corpus in the United States was suspended.

In 1867, a brick jailhouse was built (previously inmates had been kept in the basement of the guardhouse), and in 1868, Alcatraz was officially designated as a long-term detention facility for military prisoners.

Among those incarcerated at Alcatraz were Confederates caught on the West Coast[5] and some Hopi Native American men in the 1870s, who refused orders to send their children away from their families to Indian boarding schools.

[18] In 1909 construction began on the huge concrete main cell block, designed by Major Reuben Turner, which remains the island's dominant feature.

[18] During World War I, the prison was used to hold conscientious objectors, including Philip Grosser, who wrote a pamphlet entitled Uncle Sam's Devil's Island about his experiences.

[5] During the 29 years it was in use, the prison held some of the most notorious criminals in American history,[5] including gangsters such as Al Capone, Robert Franklin Stroud (the "Birdman of Alcatraz"), George "Machine Gun" Kelly and Bumpy Johnson, and political terrorists such as Rafael Cancel Miranda, a member of the Puerto Rican Nationalist Party who attacked the United States Capitol building in 1954.

[29] Others included Mickey Cohen, Arthur R. "Doc" Barker, and Alvin "Creepy" Karpis, who served more time at Alcatraz than any other inmate.

A number of employees of the Bureau of Indian Affairs also occupied Alcatraz at that time, including Doris Purdy, an amateur photographer, who later produced footage of her stay on the island.

[38] During the occupation, President Richard Nixon rescinded the Indian termination policy, designed by earlier administrations to end federal recognition of many tribes and their special relationship with the US government.

[40] It has since been under the direction of the Golden Gate National Recreation Area and now operates as a tourist site and museum dedicated to its time as a federal penitentiary.

[42] This plan, approved in 1980, doubled the area of Alcatraz accessible to the public, in order to enable visitors to enjoy its scenery and bird, marine, and animal life.

Supporters collected 10,350 signatures – sufficient to have it placed as a proposition on the presidential primary ballots in San Francisco for February 5, 2008.

[49] The coastal environment of the San Francisco Bay Area has caused deterioration and corrosion of building materials throughout Alcatraz.

[51] The 2018 report indicated that "former prison buildings are being conserved and seismically upgraded and additional areas of the Island are opened to the public as safety hazards are removed".

In 2014, Chinese artist/dissident Ai Weiwei staged an exhibition which explored "questions about human rights and freedom of expression" called @Large.

Many species of roses, succulents, and geraniums are growing among apple and fig trees, banks of sweet peas, manicured gardens of cutting flowers, and wildly overgrown sections of native grasses with blackberry and honeysuckle.

Duel Monsters, the book Al Capone Does My Shirts and the video game Tony Hawk's Pro Skater 4 as a playable level.

It is also showcased as a playable racetrack in the 1997 arcade racing video game San Francisco Rush the Rock: Alcatraz Edition.

A segment of Alcatraz' Cellhouse makes a cameo appearance in Call of Duty: Black Ops III in the downloadable zombie survival map "Revelations".

episode "Bird Mummy of Alcatraz" and was also featured in a mission in the video game Watch Dogs 2 where you can walk around and visit the island.

In the novel The Battle of the Labyrinth by Rick Riordan (part of the Percy Jackson & the Olympians series), Alcatraz serves as the prison of the Hundred-Handed One Briares, guarded by the monster Kampê.