The Gavarnie valley is mainly known for its Cirques (Gavarnie, Troumouse, Estaubé) whose different overlapping layers of limestone are clearly visible in places. Many of the summits are over 3000m/9,800ft high. Here too the development of spa resorts opened the area up in the 19C when paved roads were built. The valley began attracting and inspiring a number of "Pyrenean fans", naturalists, artists and writers.