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.
The figure, which is hard to see from the ground, is hidden in the cathedral's fresco number 20 painted by Giotto. Sergio Fusetti, the chief restorer on the progect, told Reuters that the artist likely never wanted the devil to be prominently featured, and may have incorporated it in order “to have a bit of fun.” It's also possible Giotto painted the face to spite someone he knew, portraying the person as the devil.
The basilica is located in the convent where St. Francis is buried, and, according to the BBC, was last restored after being severely damaged in a 1997 earthquake.\
The Face (It's located just below the swath of cloth, in the middle of the image):