The City and County of San Francisco is the fourth most populous city in California and the 14th most populous city in the United States, with a 2007 estimated population of 764,976.

One of the most densely populated major American cities, San Francisco is part of the much larger San Francisco Bay Area, which is home to approximately 7.2 million people.

The city is located on the tip of the San Francisco Peninsula, with the Pacific Ocean to the west, San Francisco Bay to the east, and the Golden Gate to the north. In 1776, the Spanish settled the tip of the peninsula, establishing a fort at the Golden Gate and a mission named for Francis of Assisi. The California Gold Rush in 1848 propelled the city into a period of rapid growth.

After being devastated by the 1906 earthquake and fire, San Francisco was quickly rebuilt. San Francisco is a popular international tourist destination renowned for its steep rolling hills, eclectic mix of Victorian and modern architecture, and famous landmarks, including the Golden Gate Bridge, Alcatraz Island, the cable cars, Coit Tower, and Chinatown.

The city is also known for its diverse, cosmopolitan population, including large and long-established Asian American and LGBT communities. While the climate includes chilly summer fog, the winters are mild. 
San Francisco's gay village is most concentrated in the business district that is located on Castro Street from Market Street to 19th Street. It extends down Market Street toward Church and on both sides of the Castro neighborhood from Church Street to Eureka Street.

Although the greater gay community was, and is, concentrated in the Castro many gay people live in the surrounding residential areas bordered by the Mission District, Noe Valley, Twin Peaks, and Haight-Ashbury neighborhoods. Some consider it to include Duboce Triangle and Dolores Heights which both have a strong LGBT presence.

Castro Street itself runs south through Noe Valley, crossing the 24th Street business district, and terminating a few blocks farther south as it moves toward the Glen Park neighborhood.