Hayward ( /heɪwərd/; formerly, Haywards, Haywards Station, and Haywood) is a city located in the East Bay in Alameda County, California. With a population of 144,186, Hayward is the sixth largest city in the San Francisco Bay Area, the third largest in Alameda County, and is located on the Bay's eastern shore, primarily between Castro Valley and Union City, at the eastern terminus of the San Mateo-Hayward Bridge. Hayward was ranked as the 37th most populous municipality in California. It is included in the San Francisco-Oakland-Fremont Metropolitan Statistical Area by the US Census.The former city of Mount Eden is now part of Hayward.
Human habitation of the greater East Bay, including Hayward, dates from at least 4000 B.C.E.. The most recent pre-European inhabitants of the Hayward area were the Native American Ohlone people.
In the 19th century, the land that is now Hayward became part of Rancho San Lorenzo, a Spanish land grant to Guillermo Castro in 1740. The site of his home was on Castro Street (now Mission Boulevard) between C and D Streets, but the structure was severely damaged in the 1868 earthquake on the Hayward Fault that runs directly under that location. In 1930 that site was chosen for the construction of the City Hall which served the City until 1969. The surrounding area is still the center of town.