San Francisco Bay is the artificial and flat Treasure Island, site of the 1939 Golden Gate International Exposition. From the Second World War until the 1990s, both islands served as military bases and are now being redeveloped. Isolated in the center of the Bay is Alcatraz, the site of the famous federal penitentiary. The federal prison on Alcatraz Island no longer functions, but the complex is a popular tourist site. Despite its name, Mare Island in the northern part of the bay is a peninsula rather than an island. San Francisco Bay is thought to represent a down-warping of the Earth's crust between
Alcatraz Island August 1934. Alcatraz was designed to hold prisoners who continuously caused trouble at other federal prisons. At 9:40 am on August 11, 1934, the first batch of 137 prisoners arrived at Alcatraz, arriving by railroad from the United States Penitentiary in Leavenworth, Kansas at Santa Venetia, California, before being escorted to Alcatraz, handcuffed in high security coaches and guarded by some 60 special FBI agents, U.S. Marshals and railway security officials. Most of the prisoners were notorious bank robbers and murderers. The prison initially had a staff of 155, including the first warden James A. Johnston and associate warden J.