The World's Great Unsolved Art Heists

Mohammed Mahmoud Khalil Museum, Cairo;

It's hard to believe that dramatic Thomas Crown Affair-style art thefts could actually happen in real life, but recent heists in Belgium, Egypt, and France have proven that museums should rethink their security systems. When four men broke into the Norway's National Gallery in 1994 and stole its version of Munch's famous The Scream, the thieves left a snarky note that said, "Thanks for the poor security."