Martinez is a city in and the county seat of Contra Costa County, California, in the East Bay of the San Francisco Bay Area. The population was 35,824 at the 2010 census. The downtown is notable for its large number of preserved old buildings and antique shops. Martinez is located on the southern shore of the Carquinez Strait in the San Francisco Bay Area, directly facing the city center of Benicia and the southeastern end of Vallejo, California.HistoryIn 1824 the Alhambra Valley was included in the Rancho El Pinole Mexican land grant to Ygnacio Martínez. In 1847, Dr. Robert Semple contracted to provide ferry service from Martinez to Benicia, which for many years was the only crossing on the Carquinez Strait. By 1849, Martínez served as a way station for the California Gold Rush. The town was laid out in 1849 by Col. William M. Smith and named for Martinez. It became the county seat in 1850, but could not incorporate at the time because it lacked the 200 registered voters required, and only became a city in 1876.