France's western Brittany region is home to a mysterious phenomenon, a series of “standing stones” known as megaliths. These fascinating structures are proof of a civilization that existed 7,000 years ago. Questions are still being asked about why they were built, what they symbolise and what they tell us about how people lived at that time. Many experts like Yves Coppens, who co-discovered the skeleton Lucy in 1974, are still trying to unlock the stories behind the vertical stones.