There is much speculation in regards to Leonardo da Vinci's "Mona Lisa."
Wikipedia Encyclopedia states:
"Mona Lisa is named for Lisa del Giocondo,a member of the Gherardini family of Florence and Tuscany and the wife of wealthy Florentine silk merchant Francesco del Giocondo."
"The painting was commissioned for their new home and to celebrate the birth of their second son, Andrea."
Even though it would be humorous to think Leonardo painted his own face into the painting, I think it is a portrait of Lisa del Giocondo.
