The Nazi gold train

One of Europe’s most persistent treasure hunts. As the Reich collapsed in 1945, a train said to be loaded with looted gold, art and jewels supposedly vanished into the tunnel system the Germans had bored under the Owl Mountains in what is now Poland (Project Riese, a vast unfinished underground complex). In 2015 two men announced they had found it with ground radar; the official survey found only soil and pipes. The tunnels are real and open to visit; the train has never been found.