The mystery of "Who was Mona Lisa?" has now been solved.

Many art historians have speculated that Da Vinci’s model was Lisa Gherardini, the wife of a wealthy Florentine merchant named Francesco del Giocondo (which is why Europeans refer to the painting as "La Giaconda").  But that was just a guess.

Recent notes from Leonardo himself have been uncovered and translated, and the mystery is solved.  Turns out the historians were right.