The City and County of San Francisco is a city and county in northern California, on San Francisco Bay. San Francisco was founded in the 18th century by Spanish colonists, but its population exploded during the California gold rush of 1848. San Francisco continued to be the largest city in California through the 19th century, but the 1906 San Francisco earthquake and consequent fire devastated the city. Los Angeles overtook San Francisco as the largest Californian city in the 1920s. San Francisco remains a major center of technology due to its proximity to Silicon Valley. San Francisco is also known for its liberalism and gay culture. San Francisco is well-known for the Golden Gate Bridge.