Neanderthals created two ring-shaped structures and several round piles out of almost 400 broken stalagmites deep inside Bruniquel Cave, France, 176,000 years ago.

These structures are over 300 meters from the cave entrance, and some of them were clearly burned by fires set by Neanderthals.

The function of the structures - which are among the oldest well-dated constructions made by early humans - is unknown, but they may have had a domestic or ritual function.

The research was reported in the journal Nature by Jacques Jaubert and colleagues on May 25, 2016.