The City and County of San Francisco is the fourth-largest city in California and the fourteenth-largest in the United States, with a 2005 population of 739,426. It is located on the tip of the San Francisco Peninsula and is the focal point of the San Francisco Bay Area, whose population is seven million. San Francisco is the second most densely populated major American city, after New York.

San Francisco has a unique mix of physical characteristics, including its months-long episodes of fog, its steep rolling hills, its eclectic mix of architecture (including Victorian style houses and modern highrises), and being surrounded on three sides by the Pacific Ocean and the San Francisco Bay. Famous hallmarks and landmarks include the San Francisco cable cars, the Transamerica Pyramid, the Golden Gate Bridge and Alcatraz Island.

The median income for a household in the city was $55,221, and the median income for a family was $63,545, one of the highest in the United States at 15th place overall and third in a single large city. Males had a median income of $46,260 versus $40,049 for females.

A further wave of economic expansion and physical development began in the mid 1980s with a boom in construction of skyscrapers and condominiums that some referred to as "Manhattanization". During the dot-com boom of the 1990s, large numbers of entrepreneurs and computer software professionals moved into the city, followed by marketing and sales professionals that changed the social landscape as once poorer neighborhoods became gentrified, driving up rents, housing prices and the cost and standard of living. When the dot-com bubble burst in 2001, it had a major impact on the city's employment and venture-capital markets as many of these companies and their employees left. High technology continues to be a mainstay of San Francisco's economy in the early 21st century. In addition, another wave of Manhattanization has started in the city in the mid-00's, with highrise condos sprouting in places like South of Market and Rincon Hill (also see One Rincon Hill. This second wave of highrises will significantly alter the San Francisco skyline once again and possibly take back the title of the tallest building on the West Coast from Los Angeles. Unlike the first wave of towers, this second wave has met little in the way of opposition from citizens and the city itself.

Information provided by Wikipedia .