Leonardo da Vinci's most famous, and most studied, painting was the Mona Lisa. Questions regarding the identity of the model for the Mona Lisa portrait have intrigued art students and critics for hundreds of years.
While nobody has been able to document the identity of da Vinci's model, one team of researchers concluded that the model wasn't a woman at all, but rather a man, and not just any man, but one to whom da Vinci was very close. That individual was Gian Giacomo Caprotti, also known as Salai. Salai was said to have been physically attractive, and to have worked for and been friends with da Vinci. Because little is known about da Vinci's personal life, and because the one reference to sex or sexuality in his writings was somewhat ambivalent regarding procreation, some have concluded that the artist was homosexual and that Salai was his lover. There is no evidence that this was the case beyond conjecture.