Island has quite a distinct history. Many people know that served as a federal prison, but most are reluctant to know that this island served as fort. Built before the Civil War, it served two main purposes. First, that it was to guard the San Francisco bay area from enemy ships against a foreign invasion, and second, to hold hostage prisoners of war or POW's as they were called. In this report, I'll show you how this fortress came to be a federal prison, why it is no longer in operation today, and most importantly, to show why it was built ....