To be privately owned
Ittendorf Castle

In Markdorf-Ittendorf in the Bodenseekreis district, Ittendorf Castle is situated. Originally a hilltop castle, it evolved into a palace that, together with St. Martin's Church, is considered a landmark of the town.
History+
The origins of the estate date back to the 13th century, when the Schenken von Schmalegg built a castle here. Around 1260, this complex was first documented. In 1302, the dominion changed hands when the castle and the associated village were sold to Salem Monastery, placing them under its feudal dependency. During the Peasants' War, the castle suffered severe damage. On the foundations of the former castle, Einsiedeln Monastery built the current palace in the 17th century.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Schloss_Ittendorf-7760.jpg
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: 47.7018, 9.3396