One of the most famous spas in the Languedoc Roussillon is Rennes-les-Bains, partly due to its association with Rennes-le-Château which was featured in the book The Da Vinci Code. Rennes-le-Chateau's story about the 19th century priest Bérenger Saunière and the Priory of Sion still attract hundreds of visitors to the town.
Rennes-les-Bains lies in the upper valley of the Aude near the Sals River ( which takes its name from the fact that it is naturally salty, an unusual feature for an inland river), at a height of 310m at the heart of Cathar Country, wedged between Mount Cardou and Mount Bugarach, the first foothills of the Pyrenees. There are 5 hot springs: The Bains Doux 37°C, the Bains Forts 44°C, the Bains de la Reine 40°C, the Gieulles 38°C, the Marie 39.5°C and the Yvroux at 33.1°C, and 4 cold springs: The Source des Amour, the Madeleine, the Source du Cercle and the Source du Pontet.
The origins of Rennes-les-Bains go back to antiquity and archaeological artefacts indicate that the spa was at one time popular with the Roman colony in Colonia Narbo Martius (Narbonne).The water is lightly mineralised with calcium sulphate, chlorides, thermal and hyper thermal radioactivity, magnesium and iron. The is approved by the French social security system for the treatment of Rheumatism and the effects of Osteoarticular injuries.