Before the invention of metal tools or the wheel, Stone Age engineers created extraordinary structures known as megaliths. Long shrouded in mystery, science is gradually unlocking the secrets of these ancient marvels.
From underground tombs, to immense standing stones of Stonehenge, and the spectacular monuments of Orkney. Neolithic people transported massive stones hundreds of miles using only muscle-power and the simplest of tools. Stonehenge is arguably the pinnacle of prehistoric engineering.