The Old Minnehaha County Courthouse, located at Main Avenue and 6th Street in Sioux Falls, is the former county courthouse of Minnehaha County, South Dakota. The courthouse, which was the seat of county government from 1890 to 1962, is one of the oldest buildings in Sioux Falls. The Richardsonian Romanesque building was designed by local architect Wallace L. Dow and built from locally quarried quartzite, a common building material in Sioux Falls at the time.