High Quality Content by WIKIPEDIA articles! The Washington County Courthouse is a courthouse in Fayetteville, Arkansas, United States, the county seat of Washington County, built in 1905. It was listed on the National Register of Historic Places in 1972. The courthouse is the fifth building to serve Washington County, with the prior buildings located near the Old Post Office on the Historic Square. The building is one of the prominent historic buildings that compose the Fayetteville skyline, in addition to Old Main.