The Federal Bureau of Investigation estimates that about six billion dollars worth of artworks are stolen annually. There are a number of reasons why art theft is thriving: increased market demand, open borders, improved transport systems and political instability.

Many art thefts go unnoticed for years, until the stolen works migrate to legal arts markets. Such is not the case, however, with the following heists, which were all very much noticed. From a quiet workman lifting the Mona Lisa to masked men armed with submachine guns, the following crime gallery presents some of the most audacious heists in history.