Toppler Castle (Topplerschlösschen) is a unique small castle built in 1388 by wealthy Rothenburg mayor Heinrich Toppler as a summer residence. The building has a distinctive design resembling a pond house: a massive stone base in fortified tower style topped with half-timbered upper floors. The building has been owned by the Boas family since 1861 and is furnished with furniture from the 16th to 19th centuries.