To be privately owned
Sandfort Castle

Haus Sandfort, a moated castle in Olfen in the Münsterland region, dates back to the 15th century.
History+
The construction of Haus Sandfort is dated to around 1450, with its two round towers originating from this early building phase. The upper castle underwent modifications, primarily in the late 16th and early 17th centuries. The main tower was later renovated and received its Baroque spire. The economic buildings flanking the gatehouse were added in the mid-19th century, specifically in 1851 and 1857, in a neoclassical style. Ownership changed hands multiple times: after an unnamed family, the castle passed to the Lords of Sandfort, who held it until around 1550.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.zeche.org/
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: 51.6936, 7.4172