San Diego, nicknamed 'America's Finest City', is the second largest city in California. Known for its deep coastal waters and pristine beaches, San Diego has a large number of residences, most of which reflect the casual, laid-back, and tropical-themed atmosphere of the area. Bright or white exteriors, dramatic archways, and subtle Spanish influences are evident in the homes of San Diego, which range from one thousand square foot townhomes to six or seven thousand square foot penthouses.
The various districts that segment the city of San Diego are referred to as Community Planning Areas, of which there are 52, which were created as part of a vision of the metropolis as a 'City of Villages'. Within each of these areas are numerous individual neighborhoods, generally defined by street grids or by obvious geographical boundaries such as canyons or ridges. Some of the Community Planning Areas that are well recognized include Downtown San Diego, Balboa Park, Hillcrest, North Park, Mission Valley, Carmel Valley, the Golden Triangle, South San Diego, Del Mar Heights, Clairemont, and Navajo. While some of the communities are well-established and quite dense, many are new developments and are more spaced out. Over 100 identified neighborhoods lie within these areas, some strictly residential and some mixed-use with both commercial and housing districts.
Since San Diego is home to the largest naval fleet in the world, it is no surprise that military defense is a huge aspect of the city's economy. Other main employing sectors include tourism and leisure, international trade and business, research, wireless cellular technology, and manufacturing. Entrepreneurship is also a major pillar of the San Diego economy, as it was recently rated the best city in the country to launch a small business or start-up venture. The United States Navy and the University of California San Diego are the two largest employers, followed by Sharp Healthcare, San Diego County, and Qualcomm.