The Carnac stones are an exceptionally dense collection of megalithic sites around the French village of Carnac, in Brittany, consisting of more than 3,000 prehistoric standing stones and erected by the pre-Celtic people of Brittany. They are the largest such collection in the world, however their purpose has never been discovered.
It is thought that the stones were erected during the Neolithic period which lasted from 4500 BC until 2000 BC, but in reality archaeologists have had great difficulty in establishing accurate dates as little material was found beneath them that could be used for radiocarbon dating.
Local myth states that a Roman legion was on the march when the wizard Merlin turned them into stone. Since then, a wide variety of theories have been put forward to explain the purpose of these mysterious stones. One researcher who studied the stones purported that they may have been an elaborate earthquake detector. There is another theory that the stones were erected by ancient people to honour their ancestors, still others think they were astronomical in nature. Alexander Thom, who has surveyed many megaliths in Britain and France, believes that Carnac was a huge lunar observatory.
Research is going on now to try to find out if these stone markings served as sites for astronomy or whether they were aligned with the Sun or Moon in a special way.