New discoveries at the Calanais site in Lewis, Outer Hebrides could potentially change what archaeologists think might have been the reasons behind the building of stone circles. Research by St Andrews, Bradford and Lampeter University along with the Urras nan Tursachan, Calanais Visitor Centre, have discovered evidence of a massive lightning strike at the very centre of Site XI stone circle.  The discovery was made during investigations of the buried Neolithic landscape onshore around the most famous Tursachan site.  The research also involved a survey of Loch Roag to the west of the site as this drowned landscape may also hold further clues to the life and times of the Neolithic people that constructed the circles. Further investigations are planned both on land and on the water in 2020. The findings are due to be discussed on Landward Thursday 9th April @ 2000 on BBC Scotland and Friday 10th April @ 1930 on BBC1 Scotland.