Washington County Kansas has 8 places on the National Register of Historic Places including 1 place of National significance and 2 places of Statewide significance. Significant places include Hollenberg Pony Express Station, Site No. JF00-072 and Washington County Kingpost, Mahaska Rural High School #3 and Washington County Courthouse.
Some of the country's most noteable architects helped create the Washington County places including G.H. Hollenburg, James C. Holland, Blaser and Vollmer, Zeigler & Dalton and Overend and Boucher. Prominent architectural styles found in Washington Country are Art Deco, Gothic Revival and Queen Anne.