Cave of Niaux
The 55th longest cave in the world
The Cave of Niaux (French: Grotte de Niaux) is located in the Niaux commune, Ariège département in southwestern France as part of a wider geological system that includes the Sabart Cave and Lombrives Cave in the hill of Cap de la Lesse de Bialac. The Niaux Cave's system is complex and has a combined length of more than 14 km (8.70 mi) of underground passages and chambers. An archaeological site with a documented history of paleo-human presence, Niaux contains numerous distinct areas and galleries of carefully drawn and vivid wall paintings, executed in a black-outlined style typical of the classic Magdalenian period, between 17,000 and 11,000 years ago.
Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).