The former library now houses Petaluma poultry, dairy, and Miwok Indian history exhibits from the 1850s. The cornerstone for this stately Carnegie Library was laid in 1904. The building, designed by local architect Brainerd Jones and built from locally quarried stone, features the largest free-standing leaded glass dome in Northern California. The building is in the neo-classical style, featuring original fan-glass windows, round leaded-glass windows, also original interior wood paneling and columns. It also houses a fine research library.