Castro Valley is an unincorporated town in Alameda County in the Bay Area of California. It has a population of about 50,000 and is located north of Hayward and east of San Leandro and south of the Oakland hills. Since it is unincorporated, Castro Valley is governed by the County of Alameda, which has its county seat in Oakland.
The blue Dublin/Pleasanton line of BART serves the Castro Valley Station from San Francisco. One stop to the west is the Bay Fair Station, which serves as a transfer station to other BART lines to the south (the Fremont line) or to the north (the Richmond line and one more transfer to get to the Pittsburg/Bay Point line).
The AC Transit bus system serves the Castro Valley area with only a few bus lines. Bus route 32 makes a circle (in both directions) connecting three BART stations: Bay Fair, Castro Valley, and Hayward.
San Leandro is Castro Valley's bustling western neighbor, home to beaches, regional parks, malls, hotels and many other attractions.