The infamous prison island is a short ferry ride from SF pier. We lined up for the 10am departure, it was already hot – someone had fainted, with many other tourists. Remarkably the crowds seemed to disperse on the island even though hundreds more would arrive every half hour. From the ferry there were excellent views of the bay and bridges.
In brief, Alcatraz was originally a fort, built before the American civil war. It then became a military prison, with large numbers of inmates during the Spanish-American war. From 1934 until 1963 it was the federal prison for the worst of the worst.
In the main prison we listened to an audio tour, which detailed some of the elaborate escape attempts – while some escapees were never found, it is hard to see anyone surviving the cold waters and strong currents in the SF bay.