For centuries, experts have been trying to figure out the reason for her enigmatic smile. Now, it's claimed that Mona Lisa may have been hiding a remarkable secret -- she was actually a man.

An Italian art historian has claimed that the model in Leonardo da Vinci's masterpiece was one of his male muses, a young man called Gian Giacomo Caprotti, whose nose and mouth bear striking similarities to those of Mona Lisa. Caprotti, who was also known as Salai, worked as an apprentice with the artist for more than two decades from 1490 and they were probably the lovers, said Silvano Vinceti, president of Italy's National Committee for Cultural Heritage.