The City and County of San Francisco is the fourth most populous city in California and the 12th most populous city in the United States, with a 2008 estimated population of 808,977. 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, giving it a density of 17,323 people/mi² (6,688.4 people/km²). It is the most densely-settled large city (population greater than 200,000) in California and the second-most densely populated large city in the United States. San Francisco is anchor to the 13th-largest metropolitan area in the country, containing 4.3 million, and is the financial, cultural, and transportation center of the larger San Francisco Bay Area, a region of 7.4 million people.
Today, San Francisco is a popular international tourist destination, renowned for its chilly summer fog, steep rolling hills, eclectic mix of Victorian and modern architecture and its famous landmarks, including the Golden Gate Bridge, cable cars, and Chinatown. The city is also a principal banking and finance center, and the home to more than 30 international financial institutions, helping to make San Francisco eighteenth place in the world's top producing cities, ninth in the United States, and fifteenth place in the top twenty Global Financial Centers.
San Francisco is located on the West Coast of the United States at the tip of the San Francisco Peninsula and includes significant stretches of thePacific Ocean and San Francisco Bay within its boundaries. Several islands—Alcatraz, Treasure Island, and the adjacent Yerba Buena Island, and a small portion of Alameda Island, Red Rock Island, and Angel Island are part of the city.
San Francisco is famous for its hills. There are more than 50 hills within city limits. Some neighborhoods are named after the hill on which they are situated, including Nob Hill, Pacific Heights, and Russian Hill. Near the geographic center of the city, southwest of the downtown area, are a series of less densely populated hills. Twin Peaks, a pair of hills resting at one of the city's highest points, forms a popular overlook spot. San Francisco's tallest hill, Mount Davidson, is 925 feet (282 m) high and is capped with a 103 foot (31 m) tall cross built in 1934.
San Francisco's climate is characteristic of the cool-summer Mediterranean climate of California’s coast with mild, wet winters and dry summers. Since it is surrounded on three sides by water, San Francisco's weather is strongly influenced by the cool currents of the Pacific Ocean which tends to moderate temperature swings and produce a remarkably mild climate with little seasonal temperature variation.