Spain's Prado Museum says it has a copy of Leonardo da Vinci's "Mona Lisa" that was painted at the same time as the original in the same studio, perhaps making it the earliest replica of the masterpiece.
A museum spokeswoman said the work was painted alongside the 16th century original that now hangs in the Louvre in Paris. It was done by one of da Vinci's key students.UPDATE. You can see it here, alongside the original.
UPDATE II. Just to be clear: it's not that the Prado Museum found the painting in its vaults all of a sudden. They had the painting and they knew about it; what they just found out is that it's a contemporary painting, not just one of the hundreds of replicasmade over the centuries.