One of California’s most iconic landmarks, Rancho Petaluma Adobe is the largest privately built adobe structure in the U.S. and served as the headquarters of General Mariano Guadalupe Vallejo’s vast 67,000‑acre ranch in the 1830s. Built in the Monterey Colonial style with thick adobe walls, hand‑hewn redwood timbers, and wide covered verandas, the two‑story complex once housed workshops, storerooms, and living quarters for Vallejo’s family and ranch workers. Today, visitors can tour the restored adobe, view authentic furniture and exhibits that bring to life California’s rancho era, and enjoy shaded picnic areas set against sweeping oak‑studded hills.