For thousands of years, our ancestors found solace in the winter solstice. Today, that belief is still reflected in the astonishing sight of the sun setting on Orkney's Maeshowe tomb. Located 10 miles off Scotland's north-eastern coast, the Orkney islands are a treasure trove of history, from the famous Neolithic village Skara Brae to the hauntingly beautiful Ring of Brodgar – a spellbinding stone circle that was a site of ritual and ceremony. However, when I visited another of Orkney's famous prehistoric sites, the Maeshowe tomb, my first impression was of an unremarkable green mound surrounded by a ditch. Despite...