The hook
The oldest building still in use in California is a small chapel here, the only one where Junípero Serra is documented to have said Mass, and out front stand the ruins of a great stone church an earthquake brought down.
01Why it's worth it
Serra founded this mission, the seventh of California's twenty-one, on All Saints' Day in 1776, and the little adobe chapel from 1782 that survives is the oldest standing building in the state still in use, its dim, painted interior more or less as it was. The mission's ambition, though, is written in ruins: the Great Stone Church, once the largest European structure west of the Mississippi, seven domes of yellow sandstone, stood only a few years before the 1812 earthquake dropped it during Mass and killed dozens. Its broken arches still stand in the courtyard, and every spring the cliff swallows famously return around March 19 to build their mud nests in them, the event the old song is about. Bells, gardens, koi ponds, and two and a half centuries of layered, complicated California history fill the grounds around it.
02How to experience it
It's in the town of San Juan Capistrano, about seven hours from the Bay, reachable by train right into town. There's an admission fee and a self-guided audio tour of the chapel, the ruins, and the gardens; give it a couple of hours. Time it near March 19 for the swallows if you can. It pairs directly with the Los Rios District, the oldest street in the state, a block away.