Longer version on the Beeb
www.bbc.com/future/story/20170810-the-medieval-lab-hidden-inside-a-famous-monument
( , Sun 13 Aug 2017, 17:09, Share, Reply)
www.bbc.com/future/story/20170810-the-medieval-lab-hidden-inside-a-famous-monument
( , Sun 13 Aug 2017, 17:09, Share, Reply)