Lewis County Missouri has 12 places on the National Register of Historic Places including 1 place of National significance and 2 places of Statewide significance. Significant places include Lock and Dam No. 20 Historic District, Henderson Hall and Lincoln School, Gray, William, House and Hay, Dr. J.A., House.
Some of the country's most noteable architects helped create the Lewis County places including COE, Edwin E. Abbott, Legg & Holloway, A.C. Waltman, McAllister & Co., J.T. McAllister and Joseph Hipkins. Prominent architectural styles found in Lewis Country are Greek Revival, Classical Revival and Italianate.