To be privately owned
Königshof Castle

In Königshof, Neusiedl am See, Burgenland, Austria, is Königshof Castle. Originally used as a Roman castrum and later as a Frankish royal court, it developed into an administrative center for Heiligenkreuz Abbey and is now privately owned.
History+
The origins of Königshof date back to Roman times, when a fortified manor, similar to a castrum, was built here to monitor the Roman road from Carnuntum to Ödenburg. In the Carolingian era, an earth castle was built on these Roman foundations, serving as a royal court for traveling emperors. Later, the area came into the possession of Hungarian kings and was finally assigned to Heiligenkreuz Abbey as a colonization area by King Imre in 1203. The Cistercians began building a monastery, which remained unfinished and was destroyed by the Turks in 1529. The castle-like manor was rebuilt in the early 17th century but was devastated by rebels as early as 1621. Abbot Christoph Schäffer had a tower clock made in 1636, and in 1676, Abbot Clemens Schäffer commissioned the construction of the large Trinity Chapel.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Gutsverwaltung Königshof, endet 1912. / Public domain via Wikimedia Commons
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 48.0108, 16.7187