The Washington County Courthouse is located at 205 Putnam Street in Marietta, Ohio. The courthouse is constructed of rusticated stone blocks for the foundation with smooth blocks rising to the roofline. The courthouse is the third for the county. The courthouse was designed and constructed by Samuel Hannaford & Sons, the same architects on the Monroe County Courthouse. The courthouse is included in the Marietta Historic District, which was added to the National Register on December 19, 1974.