16 of the world's most valuable stolen items

Raphael's Portrait of a Young Man,

The Nazis plundered billions of dollars worth of art and this 1513-14 artwork by the supreme painter of the High Renaissance was among the treasures looted. Widely regarded as the most important painting missing since World War II, the Portrait of a Young Man was taken from the Czartoryski Museum in Kraków, Poland in 1939. It was appropriated by Nazi official Hans Frank for his villa in Neuhaus, Germany but its whereabouts have been unknown since 1945.