The Doniphan County Courthouse, located in Courthouse Square in Troy, is the seat of government of Doniphan County, Kansas. The courthouse was built from 1905 to 1906 and was the fourth courthouse in the county. Architect George P. Washburn, who designed several courthouses in the state, designed the building in the Romanesque Revival style. The red brick building has a limestone base, and the building's north and south entrances feature limestone porches.