District 4, also known as Twin Peaks West, is arguably one of the most upscale districts in San Francisco. It is home to some of the most exclusive neighborhoods in the city, including: St. Francis Wood, Forrest Hill, and Balboa Terrace. Tucked between these neighborhoods, you'll find more family-friendly areas like Ingleside Terrace, Sunnyside, and Diamond Heights. A primarily residential district, this was one of the last parts of San Francisco to be developed after the Twin Peaks Tunnel was built in 1918. It has sixteen different neighborhoods, with a wide array of homes from MidCentury Modern, to Italian Villas, and everything in between. A highly competitive area, homes can be expensive and difficult to come by. Some of the most well-known names in San Francisco's vast catalogue of architects have built here including: Timothy Pflueger, Bernard Maybeck, John Galen Howard, Henry Gutterson, and Joseph Eichler.