Built in 1836 by order of Mariano Guadalupe Vallejo near present-day Petaluma, Rancho Petaluma Adobe served as the headquarters of a vast ranching enterprise and was planned as both a working center and defensive stronghold. It became one of the largest ranches north of San Francisco Bay, sustained by large-scale Native American labor in brickmaking, farming, tanning, and herding. Vallejo’s family used it seasonally while Miguel Alvarado managed daily operations. The ranch declined after 1846, when Vallejo was imprisoned and its livestock and grain were taken for the California Battalion. The surviving western half was later restored and remains a major architectural and historical landmark.