The City of San Francisco is the 4th most populous city in California and the 12th most populous city in the United States of America, with an estimated population of 808,977 (2008 estimate). The only consolidated city-county in California, it encompasses a land area of 46.7 square miles (121 km2) on the northern end of the San Francisco Peninsula, making it the second-most densely populated large city (greater than 200,000 population) in the United States. San Francisco is one of the cultural, financial and transportation centres of the west coast of America. The ‘Cable Cars’ of San Francisco form the only National Historic Landmark.
Situated near San Andreas and Hayward Faults the City is in constant fear of earthquakes. The earthquakes of 1906 and 1989 cause by the San Andres Fault, devastated the City. San Francisco's architectural structure has been influenced by the threat of this natural phenomenon. Minor earthquakes occur on a regular basis. The threat of major earthquakes plays a large role in the city's infrastructure development
Around 10,000 years ago, before the Pacific waters had breached the span now covered by the Golden Gate Bridge, the history of the Ohlone people native to San Francisco had already begun. Complex chiefdoms arose and fell, the scarce remnants of which are the infamous "shellmounds," large heaps of piled shells and other artifacts on the Bay Area's shores. San Francisco history continued untouched by Europeans until 1579 when Sir Francis Drake, the decorated English looter of Spanish galleons sailed past the entrance to the San Francisco Bay.
San Francisco history remained devoid of Europeans until 1775, when the Spanish, long having a stronghold in Southern California, ventured north on a "Sacred Expedition" led by Gaspar de Portola. In 1776, the Spanish founded the Presidio Army Base and the Catholic Church commenced capturing and enslaving the San Francisco Ohlone population.
The Gold Rush in 1848 catapulted the city into a period of rapid growth, increasing the population in one year from 1,000 to 25,000. The Comstock Lode was discovered in 1858 and San Francisco continued to reap the benefits of California's ore wealth.Just as the Gold boom busted, San Francisco history, in true San Francisco form, provided a new fire to fuel the world's dreamers—silver. The Comstock Lode was discovered in 1858 and San Francisco continued to reap the benefits of California's ore wealth.
Today, San Francisco is leading the way in new technologies, particularly in green energy and stem cell research. New developments in sustainable sources of energy are making San Francisco a magnet for investment, in addition to California laws promoting stem cell research and development. The Computer Mouse was invented in Silicon Valley