The Aiguilles Rouges are a crystalline mountainous massif of the French Prealps, opposite the Mont Blanc Massif. The colour of the iron-rich gneiss (metamorphique) mountains gives the range its name. The highest summit is the Aiguille du Belvédère at 2,965 metres (9,728 ft). At the southern end of the range, Le Brévent at 2,525 metres (8,284 ft) is accessible by a cable car in the Planpraz and the Brévent sections.