High Quality Content by WIKIPEDIA articles! The San Francisco Peninsula is a peninsula in California that separates the San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is in Santa Clara County, including the cities of Palo Alto, Los Altos, and Mountain View. The lion's share of the Peninsula is in San Mateo County, between San Francisco and Santa Clara counties, and including the cities and towns of Atherton, Belmont, Brisbane, Burlingame, Colma, Daly City, East Palo Alto, El Granada, Foster City, Half Moon Bay, Hillsborough, La Honda, Menlo Park, Millbrae, Montara, Pacifica, Pescadero, Portola Valley, Redwood City, San Bruno, San Carlos, San Gregorio, San Mateo, South San Francisco, and Woodside.