Fresno (/ˈfrɛznoʊ/ FREZ-noh), the county seat of Fresno County, is a city in the U.S. state of California.As of 2015, the city's population was 520,159 making it the fifth largest city in California, the largest inland city in California and the 34th largest in the nation.Fresno is in the center of the San Joaquin Valley and is the largest city in the Central Valley, which contains the San Joaquin Valley.It is approximately 200 miles (320 km) north of Los Angeles, and 170 miles (270 km) south of the state capital, Sacramento.resno (/ˈfrɛznoʊ/ FREZ-noh), the county seat of Fresno County, is a city in the U.S. state of California.