In recent times, technology and restoration work have helped reveal hidden images within great artworks. Here are 5 of those images.
Number 5. Patch of Grass, Vincent van Gogh. Beneath the Dutch artist's 1887 creation is the face of an unidentified subject believed to be a peasant woman. It was revealed by X-ray technology and its discovery was announced in 2008.
Number 4. The Blue Room, Pablo Picasso. The painting's moody hues communicate a certain sense of ennui, as does the expression of the man hidden behind them. Experts first suspected there was concealed image in 1954 when they noticed inconsistencies in the brush strokes.
Number 3. The Mona Lisa, Leonardo da Vinci. In 2015, a French scientist, Pascal Cotte, claimed he'd found the portrait of another woman lurking beneath the celebrated work. Though he produced a reconstruction of his discovery, many heavy hitters in the art history community cast aspersions on his claim.
RELATED: See photographs with strange optical illusions
Optical illusion photographs
Optical illusion photographs
A terrier dog driving his car on a sunny day in the Jerusalem Forest.
(Photo by Dan Porges via Getty Images)
Golden Eiffel Tower fitting on the cityscape with the real one in the background.
(Photo by Artur Debat via Getty Images)
Cows with one head
(Photo by Randi Shepard via Getty Images)
Shadow of a tennis player hitting a tennis ball
(Photo by Polka Dot Images via Getty Images)
Children using beach sand to cover themselves to give the illusion of a headless person lying on the beach.
(Photo by Douglas Sacha via Getty Images)
A woman appearing to push large beach ball
(Photo by Nine OK via Getty Images)
A man's silhouette appearing to hold the moon like a basketball
(Photo by Ovidiu Caragea / EyeEm via Getty Images)
A cloud being used as topping for an ice cream cone
(Photo by Evelyne Sieber / EyeEm via Getty Images)
An illusion of a crescent moon serving as a boat's sail
(Photo by Sten Knudtoft / EyeEm via Getty Images)
Optical illusion. This building in Paris, close to the Church of the Sacred Earth, seems to be skew, while in fact it is the green lawn that goes up hill.
(Photo by Busà Photography via Getty Images)
Two grazing donkeys seem to form one two-headed donkey
(Photo by Inbal Caspi / EyeEm via Getty Images)
A man with a horse's head instead of his own
(Photo by Mubadda Rohana / EyeEm via Getty Images)
Two cyclists on a flat boardwalk
(Photo by Cosmo Condina via Getty Images)
Optical illusion, man being kicked in the air in Salar de Uyuni, Bolivia, South America
(Photo by Harald von Radebrecht via Getty Images)
An illusion of a man throwing an airplane
(Photo by Dariusz Myszkowski / EyeEm via Getty Images)
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Number 2. Portrait of a Woman, Edgar Degas. Due to the thin oil paint the artist used in creating the piece, over time evidence there was another below began to emerge. Using x-ray fluorescence, a research team was able to identify the subject of the concealed painting as one of Degas' frequent models.
Number 1. View of Scheveningen Sands, Hendrick van Anthonissen. For decades, viewers wondered what the people grouped together on the shore were looking at. In 2014, restoration efforts revealed there was originally a beached whale on the landscape that, for any number of reasons, had been painted over.