Alcatraz, a rocky island in western California's San Francisco Bay, served as a federal prison housing the country's most dangerous criminals from 1934 to 1963. It became a National Recreation Area in 1972, and by the mid-1990s, it was attracting almost a million visitors a year. Nicknamed "The Rock," Alcatraz was a symbol of the impregnable maximum security fortress prison. During its 29 years of operation, 34 prisoners attempted escapes, but only three may have succeeded. Who were they? Discuss (http://forum.thefreedictionary.com/postst55529_Alcatraz-Closes--1963-.aspx)