 The Mona Lisa was not included because it is in such great demand among visitors to the museum; the painting remained on display in its gallery.Today the "Mona Lisa" is considered the most famous painting in the world, but until the 20th century it was simply one among many highly regarded artworks.Once part of King Francis I of France's collection, the "Mona Lisa" was among the first artworks to be exhibited in the Louvre, which became a national museum after the French Revolution.