Unterhof Castle

Unterhof Castle stands in Diessenhofen, Switzerland; it dates to the medieval period, but the identity of its original builder is not recorded.

The site first appears in documents in 1185 and became the residence of the local stewards who administered estates and rights in and around Diessenhofen. Members of this stewarding family appear in records, including a Heinrich who is attested between 1241 and 1290 and who, from 1247, served as steward of the County of Kyburg.

After the Kyburg line ended with the death of Hartmann IV, the castle estate passed in 1264 to Rudolf of Habsburg. Rudolf kept the existing stewards in their positions and the household continued under Habsburg lordship. Over the following century the complex grew. By 1399 the site had acquired an expanded east wing, laid out as distinct north-east and south-east tracts, together with a palas, and it was enclosed behind a reinforced defensive wall.

Financial decline affected ownership in the early 15th century. In 1408 the impoverished heir Hans Molli began selling parts of the property. The Swiss Confederacy took control of Diessenhofen in 1460, and with that takeover the administrative duties of the stewards ended and the Unterhof ceased to function as an official seat of authority. Ownership continued to change hands in the later centuries. From 1474 the von Randegg family held the property. From 1627 until 1725 the Ritter von Schellenberg owned the house, and a Junker von Greuth later sold it to the town of Diessenhofen in 1725.

Under municipal ownership the former castle was adapted to civilian uses, converted into housing and later hosting an eye clinic. Archaeological and building analyses were carried out between 1988 and 1991. In 1990 AXA Insurance purchased the property and carried out a complete renovation. From 2002 the house operated as a seminar hotel with archaeological finds from the site displayed inside. Seminar activities ended in 2014 and the complex was sold to a real-estate company from Schaffhausen which reintroduced apartments while the older portion of the building continues to operate as a restaurant. The site is listed as a Swiss heritage site of national significance.