The northernmost and last of California's 21 Franciscan missions, San Francisco Solano anchors the northeast corner of Sonoma Plaza and is now the centrepiece of Sonoma State Historic Park. The mission complex includes the original adobe chapel from 1841 (the 1823 building was demolished) and a small museum covering the history of the California mission system and its devastating impact on the indigenous population.
The grounds are modest but well-maintained, and the collection inside is genuinely informative without sanitising the history. Entry is included in the Sonoma State Historic Park pass, which also covers the Barracks and the Vallejo Estate. Spend an hour here before wandering the plaza, and Sonoma begins to make more historical sense.