This former library now housing The Petaluma Historical Museum was designed by local architect Brainerd Jones and built from locally quarried stone. It features the largest free-standing leaded glass dome in Northern California. The cornerstone was set in 1904.
It houses a research library, poultry, dairy and Miwok Indian history exhibits from the 1850s and offers weekend tours of historic Petaluma led by costumed docents. Throughout the year, the museum features a public lecture series, guided museum tours, an outreach program for schools, an annual Victorian tea, assisted research, internships and special exhibits like the recent Vietnam Experience.