The Frohnauer Hammer Mill includes an iron forge and flood ditch, a small workshop building, and the manor house. The hammer mill was previously a grain mill, whose origins most likely date back to the earliest history of Frohnau village. Following wholesale conversion in 1621, it became a hammer mill where various metals were forged – first silver, then copper, and finally iron. In 1692, the hammer mill burned down; it was rebuilt shortly afterwards. The hammer mill ceased operations in 1904. The hammer mill association, established in 1907, acquired the facility one year later, and it was run as a museum from as early as 1909. The water-powered hammer mill is a quarry stone building with a shingle-covered hipped roof and an L-shaped layout. It is powered by water from the Sehma river, which is directed into a separate watercourse by a weir some 300 metres upriver of the forge.