Mission San Francisco Solano in Sonoma, founded in 1823, was the twenty-first, last, and northernmost mission in Alta California and the only one established after Mexico won independence from Spain. Created to extend religious and strategic influence north of San Francisco Bay and check Russian inland expansion, it grew into a substantial complex that reached its peak in 1832. Its formal mission life was brief: after secularization in 1833 it became a parish in 1834, and the Native population dispersed as the buildings declined. Restored in the twentieth century, the site endures as both a rare surviving mission complex and a witness to colonization, conversion, and Native loss.