Two bunker tunnels in the Marin Headlands of Golden Gate National Recreation Area north of San Francisco, California, constructed during WWII & used as artillery testing sites. Today they are abandoned & serve as attractions.
The Bay Area is renowned for its natural beauty, affluence, diversity, and progressive thinking new age reputation. Lots of ammenities, tours and hotels can be found all around the area.San Francisco is the cultural and financial center of the Bay Area, and has the second highest population density of any major city in North America after New York City. It is also a major tourist destination, and transport and accommodation is plentiful, ranging from luxury hotels to cheap accommodation. San Jose is the largest city in terms of population, land area, and industrial development, and is the center of Silicon Valley, a well-known high technology region. Oakland is a major manufacturing and distribution center, rail terminus/hub, and has the fourth largest container shipping port in the United States.Largely because of San Francisco and Silicon Valley, the Bay Area presently ranks second only to the much larger New York City region in number of Fortune 500 company headquarters (April 2010 Fortune Magazine). source: wikipedia