The devil was hidden in the details of clouds at the top of fresco number 20 in the cycle of the scenes in the life and death of St Francis painted by Giotto in the 13th century.
The discovery was made by Italian art historian Chiara Frugone. It shows a profile of a figure with a hooked nose, a sly smile, and dark horns hidden among the clouds in the panel of the scene depicting the death of St Francis.
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