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 self-determination, in part as a result of the publicity and awareness created by the occupation. The occupation ended on June 11, 1971. The entire Alcatraz Island was listed on the National Register of Historic Places in 1976, and was further declared a National Historic Landmark in 1986. In 1993, the National Park Service published a plan entitled "Alcatraz Development Concept and Environmental Assessment." This plan, approved in 1980, doubled the amount of Alcatraz accessible to the public to enable visitors to enjoy its scenery and bird, marine, and animal life. Today, American Indigenous groups, such as the International Indian Treaty