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 and passed suitable acts in the years 1851 and 1852 to build seven lighthouses on the West Coast to guide navigation. The Baltimore firm of Gibbons and Kelly was awarded the contract to build seven lighthouses in California, at Alcatraz Island, Fort Point, Point Pinos, Point Loma, Farallon Island, and Humboldt Bay, and one at Cape Disappointment in Washington State. Equipment were shipped on Oriole, reached San Francisco on January 29, 1853. The Alcatraz Lighthouse was the first to be completed in July 1853, making it the oldest major navigational light on the West Coast. However, the foundation for building