The building was constructed in 1859 and expanded in 1876. It served as the primary bulding for what is now Oregon State University until 1888, when the new Administration Building (Benton Hall) was completed on the west edge of the original college farm.
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.