 It is believed by some that the "Mona Lisa" was begun in 1503 or 1504 in Florence.Although the Louvre states that it was "doubtless painted between 1503 and 1506", art historian Martin Kemp says that there are some difficulties in confirming the dates with certainty.In addition, many Leonardo experts, such as Carlo Pedretti and Alessandro Vezzosi, are of the opinion that the painting is characteristic of Leonardo's style in the final years of his life, post-1513.