The Benton County Courthouse is the oldest courthouse in Oregon still being used for its original purpose. Designed by Portland architect Delos D. Neer, construction began in 1888 - the cornerstone is dated July 4, 1888 - and was completed the next year. The cost of the building was $66,689. The foundation was made from basalt and sandstone likely quarried at Witham Hill; the walls were made of locally produced brick. The courthouse was renovated in 1977-78. The building to the left of the courthouse was the county jail, also designed by Neer and built in 1888-89. It was used until 1929, when a new jail was built.
