San Francisco is a city in the northern part of California in the United States. It is one of the US’s most densely populated cities. It was founded in 1776 by Spanish colonists. It boomed in the nineteenth century, particularly after the California Gold Rush in 1849. A devastating earthquake and fire in 1906 killed three-quarters of the population. San Francisco is a popular tourist destination known for the Golden Gate Bridge, Alcatraz Prison, and Fisherman’s Wharf, as well as well-known for many counter-cultural movements, opposition to the Vietnam War, Free Love, and the gay rights movement. San Francisco is home to numerous global companies including Dropbox, Airbnb, Weebly, Uber, Lyft, Twitter, and Pinterest.