Sutro Project / Alcatraz
Notorious beyond it's size and penitential impact (Alcatraz was only a prison for 19 years), "The Rock" is an exciting afternoon - especially on a nice day. The complex is nicely restored with lots of information and many photographs. The "prison yard" has phenomenal views of the bay and the Golden Gate Bridge.
Reserve early to guarantee a spot on the boat... Otherwise, don't sweat it - take a bay tour, visit Angel Island, or maybe the Armory for similar vibes :)
Website: http://www.alcatrazcruises.com/
Wikipedia: http://en.wikipedia.org/wiki/Alcatraz
