The remains of the Castle can be visited
Château de Castelnou

In the French department of Pyrénées-Orientales, the Château de Castelnou, also known as Château Vicomtal, is a medieval castle ruin. The complex, which gave the village of Castelnou its name, is on a rocky outcrop.
History+
The origins of the Château de Castelnou date back to 990, when it became the administrative and military center of the Viscounty of Vallespir. Its irregular pentagonal shape adapted to the natural terrain, utilizing the elevated position for defense. In 1286, the castle was captured by the troops of James II of Majorca, a fate that was repeated in 1483.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Hervé Rebours
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: 42.6189, 2.7027