Depending on the exact location of Portola's camp in Christianitos Canyon, either today or tomorrow is the 240th anniversary of Orange County history itself.
On July 22, 1769, Gaspar de Portola and his expedition camped in the canyon, near what is now the border of Orange and San Diego counties. They found an Indian village there, where Fr. Crespi baptized two gravely ill children -- the first baptisms in California. (Hence, the canyon's name, which means "little Christians.")
The following day, they continued their march northward, and were (by that point) definitively in what is now Orange County.
Both Portola and Crespi kept diaries, and the expedition's engineer, Miguel Constanso, later wrote up the official narrative of the trek. They were the first Europeans in Orange County, and the first to record the experience. And without records you can't have history.