http://www.fil.lu.se/cms/section.asp?sid=1163&lang=eng
http://www.guardian.co.uk/film/filmblog/2010/apr/13/werner-herzog-cave-art-documentary-3d
"What is also strange," Herzog reveals, "is that somebody [in the cave] started a painting and then they left. And it's known that 3,500 years later somebody continued the painting..."
