Clay County South Dakota (Historic Districts) has 5 places on the National Register of Historic Places including 1 place of Statewide significance. Significant places include Johnsen, Calle Nissen, Farm, Anderson Homestead, Downtown Vermillion Historic District, Forest Avenue Historic District and Vermillion Historic District.
Some of the country's most noteable architects helped create the Clay County places including Godfrey Swanson, Arnold and Bueittler, Dow, Wallace and et al.. Prominent architectural styles found in Clay Country are Classical Revival, Bungalow/Craftsman and Early Commercial.