Perhaps one of Leonardo da Vinci’s greatest paintings has never been reprinted in books of his art. Known as the Battle of Anghiari, it was abandoned and then lost—until a determined Italian engineer gave the art world hope that it still existed, and a physicist from the U.S. Department of Energy’s Argonne National Laboratory developed a technique that may reveal it to the world once again.

The story starts in 1503 in the newly constructed “Hall of 500” of the Palazzo Vecchio, the town hall of Florence, Italy, where the city had called the geniuses Leonardo da Vinci and Michelangelo Buonarroti to each paint one wall. Leonardo chose to paint the Battle of Anghiari, and his sketches promised a marvel of motion and color worthy of his best work (figure 1).

Figure 1: Peter Paul Rubens’ copy of Leonardo’s half-finished masterpiece, The Battle of Anghiari, based on an engraving by Lorenzo Zacchia. (Enlarge image)

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