The Castle can be visited
Stolberg Castle

Stolberg Castle, a landmark in the city of Stolberg in the Aachen region, rises on a steep limestone rock in the historic old town. It is the namesake of the city.
History+
The origins of Stolberg Castle date back to the 12th century when it was built by the noble lords of Stalburg. In the 15th century, after its destruction, the complex was pledged by the Dukes of Jülich to the Lords of Nesselrode, who had it rebuilt as an open house. In the mid-16th century, Hieronymus von Efferen expanded the castle after further damage. Through marriage, ownership later passed to the Imperial Barons Raitz von Frentz. In the 18th and 19th centuries, the castle increasingly fell into ruin. In 1863, the dilapidated complex came into bourgeois possession.
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: 50.7669, 6.2328