The remains of the Castle can be visited
Château de Najac

The medieval castle ruin Château de Najac, in the French commune of Najac in the Aveyron department, is one of the most robust fortifications in its region and was never captured.
History+
The construction of the castle complex took place in several building phases. Originally, it consisted of a rectangular keep, which was later integrated into one of the corner towers of the rectangular core castle. This core castle was surrounded by eight-meter-high curtain walls. A feature is the round, 40-meter-high keep with a diameter of 11 meters.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Ch%C3%A2teau_Najac.jpg?uselang=fr
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: 44.2185, 1.9731