In San Francisco, zoning restrictions normally limit construction heights to no more than 40 feet (often 4 to 6 stories). However, special permits may be required for buildings over 30 feet tall. In addition, height limitations may not apply to certain types of buildings such as schools or hospitals. San Francisco's architecture is a mix of historic styles including Victorian, Mission, and Modern. Some famous landmarks include the Golden Gate Bridge, Alcatraz Island, and Coit Tower. The city and its surroundings contain many parks and beaches where you can go surfing, hiking, or biking. The San Francisco Bay Area has a rich ethnic diversity with over 250 languages being spoken by residents. It is known for having some of the most expensive real estate in the country. A typical house in the Silicon Valley area costs $1 million or more. Of all the cities on California's coast, San Francisco has the most expensive apartments. One square foot of an apartment in the Central District can cost up to $3000. You can find cheaper places in Oakland but it's a 15-minute train ride to San Francisco's financial district. San Francisco has the highest rate of homelessness in the country.