The Carnac stones are an exceptionally dense collection of megalithic sites around the village of Carnac, in Brittany, consisting of alignments (a linear arrangement of upright, parallel megalithic standing stones set at intervals along a common axis or series of axes), dolmens (single-chamber megalithic tomb), tumuli (mound of earth and stones raised over a grave or graves) and single menhirs (a large upright standing stone). The stones were erected at some stage during the Neolithic period, probably around 3300 BC, but some may date to as old as 4500 BC. Image taken from The Celtic Druids by Godfrey Higgins, 1827 (cropped and cleaned).