The remains of the Castle can be visited
Hardenstein Castle

Hardenstein Castle Ruin, once a moated castle and later a manor house, is situated on the middle Ruhr in North Rhine-Westphalia. Originally located directly on the river, it is now surrounded by a nature reserve.
History+
The construction of Hardenstein Castle took place between 1345 and 1354. Heinrich II von Hardenberg, who had to sell his Hardenberg lordship in 1354, settled with his family on the southern bank of the Ruhr, thus establishing the line of the Hardensteins. This family was plagued by financial difficulties. In 1378, Heinrich IV von Hardenstein waged a feud against Dortmund to settle debts with a Jewish businessman. The attack with around 1,000 men failed, and Heinrich IV was later captured and executed by Cologne troops.
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: 51.4207, 7.3015