The remains of the Castle can be visited
Volmarstein Castle

A historic structure situated on a ridge, the castle ruin of Volmarstein stands above the Ruhr in the Volmarstein district of Wetter. Originally built in 1100 by Archbishop Friedrich I of Schwarzenburg, it served to secure his claims to power in Westphalia and protected an escort route.
History+
Volmarstein Castle was constructed around 1100 by Archbishop Friedrich I of Cologne and granted as a fief to the noble lords of Volmestein. It served as the central administrative hub of the Volmarstein lordship, which also included Hagen. Following the Battle of Worringen in 1288, Count Eberhard I of the Mark besieged the castle and partially destroyed it. After a reconciliation, it was rebuilt in 1289. In the early 14th century, disputes with Münster occurred. In 1324, during a feud between the Archdiocese of Cologne and the County of Mark, the castle was again captured and destroyed, but subsequently rebuilt.
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: 51.3743, 7.3826