👉 The term 'Alcatraz' refers to a United States penitentiary in San Francisco that was closed in 1963 and is now a historic landmark. It was built on the site of Alcatraz Island, which has played a significant role in American history. The island was used as a prison from the early 20th century until 1948, when it was converted into an urban park. Today, the island and the surrounding area are listed on the National Register of Historic Places and have been designated a National Historical Park.