The Verdon Gorge is a river canyon located in the Provence-Alpes-Côte d'Azur . It is considered to be one of Europe's most beautiful attraction. It is about 25 km long and up to 700 metres deep. It was formed by the Verdon River, which is named for its startling turquoise-green colour, one of the location's distinguishing characteristics. The most impressive part lies between the towns of Castellane and Moustiers-Sainte-Marie, where the river has cut a ravine to a depth of 700 meters through the limestone mass. At the end of the canyon, the Verdon flows into the artificial lake of Sainte-Croix-du-Verdon, named the Lac de Sainte-Croix. As it is close to the French Riviera, the gorge is very popular with tourists, who can drive around its rim, rent kayaks to travel on the river or hike. The limestone walls, which are several hundreds of metres high, attract many rock climbers. It is considered an outstanding destination for multi-pitch climbing. The variety of 1,500 routes encompass cracks, pillars and seemingly endless walls, with a range in distance from 20 metres to over 400 metres. The Palais des Papes is a historical palace located in Avignon, Southern France. It is one of the largest and most important medieval Gothic buildings in Europe. Once a fortress and palace, the papal residence was the seat of Western Christianity during the 14th century.