Fairfield is a city in, and the county seat of, Solano County, California, in the North Bay sub-region of the San Francisco Bay Area. It is generally considered the midpoint between the cities of San Francisco and Sacramento, approximately 40 miles from the city center of both cities, approximately 40 miles from the city center of Oakland, less than 19 miles from Napa Valley, 16 miles from the Carquinez Bridge, and 14 miles from the Benicia Bridge. It is the home of Travis Air Force Base and the headquarters of Jelly Belly. Native Americans, such as those from the Ion culture, settled in the Rockville and Green Valley areas. Artifacts that have been found from some of the earliest human inhabitants of the Fairfield area are dated to be around five to six thousand years old, making them some of the oldest Native American settlements in Northern California.