On November 4, 1769, the expedition of Captain Gaspar de Portola, after crossing Sweeny Ridge, beheld the Bay of San Francisco for the first time. That night they camped at a small lagoon, now covered by San Andreas Lake. Finding the bay too large to go around and thinking they had by-passed Monterey Bay, the expedition camped here again on November 12, 1769 on their return to San Diego.
First made a State Registered Historical Landmark No.27, June 15, 1932, this site was rededicated as a U.S.A. Bicentennial Project of San Andreas Lake Chapter, Daughters of the American Revolution and the City of Millbrae, California on November 6, 1976
Location granted by the State of California
Monument Base of Serpentine Rock, Official State Rock of California, Furnished by the San Francisco Water Department.