Off the N117, about 45 km north-west of Perpignan, a clutch of castles in the craggy Corbière hills were the last bastion of the Cathar heretics, driven south by Simon de Montfort and the armies of the Albigensian crusaders. Eleven years after the martyrdom at Montségur, where more than 200 Cathar believers chose to die by fire rather than recant their faith, the Cathars’ final stand took place at Château de Quéribus. The stronghold’s outer defences are staggered along the crest of a hill with a single, narrow stairway leading to the keep. Reaching into the sky like a giant torch from a sheer-sided rocky outcrop 500 m above the Aude valley, the keep commands dizzying views across to the snow-capped Pyrenees and neighbouring Peyrepertuse.

Château de Peyrepertuse (open Apr-Oct) is the most awe-inspiring of the medieval castles. Measuring over 300 m from the pointed ship’s prow of the east end to the Château Saint-Georges, it rides the vertiginous ridge like a dreadnought, flanked by ruined, sun-bleached battlements.

Between Peyrepertuse and Saint-Paul-de-Fenouillet, the D10 accomplishes a minor miracle of engineering as it carves a cliff-hanging route along the Gorges de Galamus. There is a parking area with precipitous views down into the narrow ravine. A footpath leads around to the hamlet of L’Hermitage buried into the rock face.

Further west, Château de Puilaurens (18 km via the D117) lords it over the village of Lapradelle. Its crenellated walls are more or less complete, reinforced during the 17thC, and stand out etched against the sky above a sea of dark green firs.