The Thomsen Round Barn was an historical building located near Armstrong in rural Emmet County, Iowa, United States. It was built in 1912 as a dairy barn.[2] The building is a true round barn that measures 65 feet (20 m) in diameter.[3] The first floor is constructed of concrete and the second floor consists of white vertical siding. It features a two-pitch conical roof, and a 16-foot (4.9 m) central silo.[3] The barn was listed on the National Register of Historic Places since 1986.[1] As of July 21, 2014 it is no longer standing.[3]