The devil's in the details, literally.

Art restorers working on one the most famous frescoes painted by Renaissance painter Giotto di Bondone in the Basillica of St. Francis in Assisi, Italy have uncovered an astounding hidden secret painted by the artist himself. According to Reuters, Giotto hid the face of the devil himself in a fresco.

The concept of hiding a figure in the clouds, according to the BBC, was previously thought to have first been implemented by Andrea Mantegna in the 15th century. Giotto's fresco dates to the 13th century....