A restored 1846 adobe ranch house at 1000 Linda Mar Blvd with hands-on field-trip programming for students run by the San Mateo County Historical Association, plus the annual Rancho Day Fiesta (every third Saturday in September) celebrating Mexican California with music, dancers, rancho food, and hands-on crafts. Confirmed directly via the site's own pages: admission free (donations appreciated). Open Tue-Thu 10am-4pm, Sat-Sun 12pm-4pm.