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 "Tony Hawk's Pro Skater 4" as a playable level, and in the video game "" in a downloadable zombie survival map called "Mob of the Dead". It is also featured as a playable racetrack in the 1996 arcade racing video game "". Alcatraz has also been portrayed often as a safe haven or base of operations in many post-apocalyptic movies, such as "The Book of Eli". Alcatraz even appears in "The Alchemyst" and "The Sorceress" by author "Michael Scott" and is depicted as a prison for the immortal "Perenelle Flamel". Alcatraz is featured in the episode "Bird Mummy of Alcatraz"