A French scientist thinks he's discovered another image hiding underneath the famous painting of the Mona Lisa.
Pascal Cotte spent more than 10 years using light technology to analyse the picture.
And he thinks that there is a portrait of a different person painted beneath the Mona Lisa.
The Mona Lisa, which was painted by Leonardo da Vinci, is one of the world's most famous paintings.
However, some art experts are not convinced that there is a different painting underneath.
They say that other images might just be da Vinci's first attempts at the Mona Lisa.