The Mona Lisa has a new twin.

In the process of restoring a painting that has been in Madrid’s Museo del Prado since 1819, conservators have discovered a near-exact copy of the famous portrait hidden beneath a black coat of overpaint. While there are many such copies in circulation, the Prado’s version is unique in that it was painted in Leonardo da Vinci’s studio by one of the master painter’s favourite pupils, and at the same time as the original. Standing in front of the work a day after its unveiling in Madrid, I could not help but wonder whether the copy surpasses the original: the youthful beauty and vigour of da Vinci’s most famous model shines through in a way that is obscured beneath the cracked varnish of the Louvre’s more famous version. The Prado’s Mona Lisa was reunited with the original in the Louvre on 13 March, and will return to Madrid later in 2012.

Anthony Ham is the author of Lonely Planet’s Madrid and Spain guides. This article was published in partnership with Lonely Planet Magazine.