An Italian researcher claims the model for the world's most famous painting may have been a male apprentice who worked with da Vinci for more than 20 years.
He is believed to also have been romantically involved with the artist.
The new theory is based on similarities between the apprentice's nose and mouth and those of the Mona Lisa's.
But many da Vinci experts contend that the wife of a wealthy Florentine merchant is the basis for the painting.
