For most of the year, the rotating lantern atop Mount Diablo's summit building sits dark. On a few nights, though, the "Eye of Diablo" lights up again. It's one of the last working beacons from the string of lights that once guided pilots across the country.

A light for the first airlines

According to a Cal State East Bay timeline, Standard Oil built the beacon in 1928 as the first of California's five aviation beacons, back when pilots flying airmail and early passenger routes needed lights on the ground to navigate at night. Save Mount Diablo says the beacon was first lit by Charles Lindbergh. The Civilian Conservation Corps built the stone summit building that now holds it in 1939.

Dark for 23 years

The beacon shone every night until Dec. 8, 1941, the day after the attack on Pearl Harbor. Cal State East Bay notes it was switched off because of fears enemy submarines could use it to navigate. It stayed dark until Dec. 7, 1964, when Fleet Admiral Chester Nimitz, the wartime commander of U.S. Pacific forces, attended a ceremony on the summit honoring Pearl Harbor survivors. He suggested the beacon be lit every Dec. 7 to honor those who served and sacrificed.

The Pearl Harbor Survivors Association kept up that tradition for decades. Today the Sons and Daughters of Pearl Harbor Survivors carry it on, co-sponsored by Save Mount Diablo. "When that Beacon light is turned on, that's a tribute to those individuals who lost their lives at Pearl Harbor," survivor Earl "Chuck" Kohler said, as quoted by Save Mount Diablo.

Saved by a snowstorm

A 2009 snowstorm revealed how badly the beacon had deteriorated, according to Cal State East Bay. In 2010, Assemblymember Joan Buchanan carried legislation that let Save Mount Diablo oversee a restoration on behalf of California State Parks. Shell's Martinez refinery and Maxim Crane donated a crane and crew to lift the lantern out and put it back. The Dean and Margaret Lesher Foundation matched donations up to $50,000 toward a $100,000 goal, and the work was finished in 2013.

When to see it

Save Mount Diablo says that beginning in 2022, the beacon has also been lit on Memorial Day and Veterans Day to honor veterans. The main ceremony is still on Dec. 7. It's held at the Cal State East Bay Concord campus on Ygnacio Valley Road, where the university displays a piece of the USS Arizona's boat deck that it received in 2020, and it ends with the beacon lighting at 5 p.m. On lighting nights, look up at the summit from almost anywhere in central Contra Costa County.