Since 2011 I’ve been working on a book on the history of stone quarries. Nidaros cathedral, the northernmost of Europe’s great medieval cathedrals forms the key case study. Historic picture from its most important modern quarry – Bjørnå in Nordland County – after a very troublesome rock fall in the 1920s. Many thanks to The Restoration Workshop (NDR) and The Geological Survey of Norway for publishing the book in 2015. (See under “Publications” at my website.) Photo by NDR