Copy of Mona Lisa
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Art historians find copy of the Mona Lisa

1 February 2012 Last updated at 19:17 GMT

Art historians say they have found a copy of the Mona Lisa, which they believe is probably painted by one of Leonardo Da Vinci's own pupils.

It is claimed the find will transform understanding of the world's most famous picture.

The BBC's arts editor Will Gompertz reports.