The secret behind the famously enigmatic smile of the Mona Lisa, the world's most famous painting, could soon be solved.

Archaeologists on a dig in Italy claim to have discovered the skull of the woman who posed for Leonardo's da Vinci's  masterpiece.

The excavation team revealed over the weekend that it had found a crypt after a two-week search at an abandoned convent in Florence.

But the grave beneath St. Ursula convent, believed to be the final resting place of Lisa Gherardini Del Giocondo, has now yielded a female-sized skull.

The merchant's wife is widely believed to have been the life model for da Vinci's best-known work.

Officials say the skull was found five feet under the convent's original floor along with other fragments of human ribs and vertebrae.

Now scientists will compare the DNA in the bones with the remains of the model's two children who were buried nearby in an attempt to authenticate the find.

If scientists can confirm the skull belongs to the model, forensic artists will then attempt to reconstruct her face to see how it compares to the 500-year-old version painted by da Vinci - and perhaps solve the riddle of the Mona Lisa's enigmatic smile in the process.

Archeologist Silvano Vinceti, who is in charge of the dig, explained: 'We don't know yet if the bones belong to one single skeleton or more than one.

'But this confirms our hypothesis that in St.Ursula convent there are still human bones and we cannot exclude that among them there are bones belonging to Lisa Gherardini.'