The Nauvoo House in Nauvoo, Illinois is a boarding house that Joseph Smith, Jr., the founder of the Latter Day Saint movement, began constructing in the 1840s. The boarding house was never completed, but the structure was later converted into a residential home and renamed the Riverside Mansion. The Nauvoo House, as it is referred to today, is part of the Nauvoo Historic District, a National Historic Landmark.