Alcatraz, off the coast of San Francisco, was once an infamous prison. Now it’s most well known as the top tourist attraction in the city. Often referred to as “The Rock”–and for good reason, it more or less is one–it served as a federal prison from 1933-1963. Some of the most notorious prisoners in the US were housed here, including: Al Capone, James "Whitey" Bulger, and Mickey Cohen. Visiting it can feel a bit creepy at times as you walk the halls of the prison, but it’s a must-see on any trip to San Francisco.