The Château d'Usson is one of the so-called Cathar castles in what is now southwestern France. It is located in the commune of Rouze, in the Ariège département. It is sited upstream from Axat, along the Aude River gorge, carved out of the foothills of the Pyrenees. It is situated at 920 m in altitude and dominates the valley of the Aude River.