The Corson Emminger Round Barn near Watertown, South Dakota, United States, is a round barn that was built during 1909-1910 by Corson Emminger. It was listed on the National Register of Historic Places in 1978.
It is "extremely tall", on a diameter base. It is built of concrete blocks. It has a double-pitched roof topped by a polygonal cupola with a conical top. It used to have ramps leading to two large entrances on the second level.
There are few round barns in South Dakota; Emminger may have brought the idea of building one from Wisconsin, his native state, from which he arrived in the early 1900s. He bought the farm property in 1905 for $6,000, and he built the barn at cost of $1,500 to use as a dairy barn. He moved into Watertown in 1914 and to California in 1920. Jacob Krull bought the farm for $13,600 and owned it, with exception of one year, until 1943.
Its National Register nomination asserts it is "truly a landmark in South Dakota", noting that it is located on one of the state's main highways.
It is located on U.S. Route 81, about west of parallel Interstate 29.