Just north of Sonoma Plaza, this often overlooked museum is stuffed with intriguing artifacts, such as painted stage curtain from the long-gone Union Hotel (now a modern bank on the southwest of the square), complete with era ads painted onto it; it was found rolled up in a barn. The women in charge of the place are generous and excited; ask to hear the 1850s Swiss music box and they’ll tune it up for you. Not all the exhibits in this museum are labeled so just ask questions—they love telling tales here.