The Dubuque County Historical Society (DCHS) strives to collect, preserve and share the rich history of Dubuque County, the Mississippi River, and Rivers of America. In addition to the National Mississippi River Museum & Aquarium, the DCHS has a number of other properties that share this mission.     Ryan House 1375 Locust Street Open by appointment for tours/events   The Mathias Ham House 2241 Lincoln Avenue Open weekends in May, daily Memorial Day through September 1st, weekends in September and October, 10am to 5pm (last tour begins at 4:30pm).   The Old Jail Museum 8th and Central Open Wednesday - Saturday, 11:00 a.m. to 4:00 p.m.