Bruniquel Cave

Bruniquel Cave in southwest France, had been naturally closed during the Pleistocene period (which began 2.6 million years ago and lasted until about 11,700 years ago). When researchers opened the cave in 1990, they found on the cave floor two ring-shaped constructions made of whole and broken stalagmites. The regular geometry of the arrangement of the broken stalagmites, alongside fireplaces indicates the human origin of the construction, which has been dated to 176.5 thousand years BCE. These edifices are among the oldest known well-dated human constructions. During the time of this construction early Neanderthals were the only humans in Europe. The site is 336 meters (1102 feet) from the cave entrance, which indicates these humans had mastered navigation of the underground cave environment, unexposed to daylight, a major development toward modern humans. This kind of cave deep-habitation happened only in Europe and not previously in Africa, where only cave entrances and stone shelters had been occupied by humans. The humans of Bruniquel had mastered complex spatial organization in the annular construction, use of fire for heat and light, and deep karst occupation--all indicating a level of social organization that was more complex than previously known.

Elevation: Cave entrance is 165 meters (541 feet) above sea level.

Sources:
1.Rouzaud, F., Soulier, M. & Lignereux, Y., 1996; La grotte de Bruniquel. Spelunca 60, 27–34, 1996
2. Jaubert, J. et al. 2016; Early Neanderthal constructions deep in Bruniquel Cave in southwestern France, Nature 534, 111–114 (02 June 2016)
www.nature.com/doifinder/10.1038/nature18291