Alcatraz Island 1906 San Francisco earthquake, civilian prisoners were transferred to Alcatraz for safe confinement. On March 21, 1907, Alcatraz was officially designated as the Western U.S. Military Prison, later Pacific Branch, U.S. Disciplinary Barracks, 1915. In 1909 construction began on the huge concrete main cell block, designed by Major Reuben Turner, which remains the island's dominant feature. It was completed in 1912. To accommodate the new cell block, the Citadel, a three-story barracks, was demolished down to the first floor, which was actually below ground level. The building had been constructed in an excavated pit (creating a dry "moat") to enhance
Alcatraz Wharf and sank in deep water off the wharf in the early 1910s. Her crew of forty-two men escaped by jumping into the bay and swimming ashore. Seismic rehabilitation of the wharf occurred in the early 2000s. The retrofit to the existing wharf and its facilities consisted of concrete demolition, excavation, and installation of tiebacks. Reinforced steel and concrete were added to a new deck. Work was also done on the deteriorated piles under the wharf deck.David Finney is the youngest person to swim the South End Rowing Club Alcatraz Swim when he swam it in 2015 at ten years old.