When did Alcatraz open and close?

Alcatraz Federal Penitentiary
Alcatraz Island
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Capacity 312
Opened 11 August 1934
Closed 21 March 1963

What was Alcatraz originally built for?

In the 1850s the United States army built a fortress there, to protect San Francisco, but it was never needed and in 1868 it became a military prison. In 1909 most of the original fortress was demolished and a new prison was built, which became known as ‘The Rock’. The work was done by the prisoners themselves.