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 Lighthouse to earthquake in 1906. The automation of the lighthouse with a modern beacon took place in 1963, the year Alcatraz closed as the Alcatraz Federal Penitentiary. It is the oldest light station on the island with a modern beacon and is part of the museum on the island. Although when viewed from afar it easily looks the tallest structure on Alcatraz, it is actually shorter than the Alcatraz Water Tower, but as it lies on higher ground it looks much taller. Even though the Native Indians of the San Francisco area are stated to be the original settlers on the