The Round Barn, Washington Township is an historic structure located south of Janesville, Iowa in Black Hawk County. It was built in 1917 as a dairy barn, and has been listed on the National Register of Historic Places since 1986. The building is a true round barn that measures 60 feet (18.3m) around. The structure is constructed in clay tile and features an aerator and a two-pitch roof. It was built around a silo with a water tank on top of it. While that is typical of this type of structure, it is the only one known to exist in Iowa.
