Gregory County South Dakota has 13 places on the National Register of Historic Places including 1 place of National significance and 2 places of Statewide significance. Significant places include Fort Randall, South Dakota Dept. of Transportation Bridge No. 27-000-201 and South Dakota Dept. of Transportation Bridge No. 27-060-298, Dallas Carnegie Library and Gregory Buttes Stone Steps.
Some of the country's most noteable architects helped create the Gregory County places including Standard Bridge Company, Caspary and Simons and John Hayes. Prominent architectural styles found in Gregory Country are Romanesque, Early Commercial and Greek Revival.