Marker text: NO. 905 MOUNT DIABLO - Mount Diablo had been a home with spiritual significance to the Costanoan Indians for at least 500 years when Spanish explorers viewed the mountain in 1772. In 1851 Mount Diablo was selected as the initial point for land surveys of Northern California and Nevada, with the Mount Diablo Base and Meridian Lines originating at its peak. Due to the mountain's variations in wind, rainfall, and temperature, it is also a preserve for a wide variety of plant and animal life.
California Registered Historical Landmark No. 905
Plaque placed by the State Department of Parks and Recreation in cooperation with the San Ramon Valley Historical Society, April 23, 1978