For centuries many have pondered what lies behind the Mona Lisa's enigmatic smile, but it was more of a rhetorical question. Now art lovers can literally discover what the back of Da Vinci's masterpiece looks like.
In a unique and quirky Dutch exhibition, Brazilian artist Vik Muniz displays about 15 painstakingly recreated exact reproductions of the backs of some of the world's most famous paintings.
There's Vincent Van Gogh's "Starry Night" leaning facing the wall across the room from Vermeer's "The Girl with a Pearl Earring". A massive, almost bare, wooden frame is the stark reverse side of Rembrandt's haunting "The Anatomy Lesson of Dr Nicolaes Tulp".
The paintings looking shockingly exposed, their backs bared, and visitors to the exhibition at the Mauritshuis museum in The Hague could be forgiven for thinking they have accidentally wandered into a storage room.
But a closer look reveals a fascinating trip into the history of each painting, who owned it and where it travelled, as well as changing tastes in art conservation.
On his first museum visit as a schoolboy, Muniz was instantly intrigued not by the artworks, but by the mechanics and artistry of their backs.
The Museum of Art of Sao Paulo had displayed the paintings on glass easels and exiting the building the backs were boldly on display for all to see.
As "an eight-year-old I wasn't very interested in paintings. I was very fascinated that all the paintings from the back, they looked like machines, contraptions. They looked like things that did things," Muniz told AFP.
"And in fact they do. They serve a purpose. They are instruments for preserving history."
- Seeing a painting 'naked' -
His curiosity was later revived in a startling moment when as an adult on a visit to the Guggenheim in New York, he was given a look at the back of Picasso's "Ironing Woman".
"It was like looking at a naked person," he recalled. An interest was reborn, and when photographing the backs of paintings failed to satisfy his creative spirit, he conceived the idea of actually copying the backs of some of the world's best-loved masterpieces.
It was not always simple. It took six years of negotiations with the Louvre in Paris to be able to study the back of "The Mona Lisa."
The "Vik Muniz: Verso" exhibition, which opened on Thursday in The Hague until September 4, is now the first full show of these works.
It is extraordinarily intimate, drawing the visitor back through the centuries, forcing them to peer closely at what are more usually neglected parts of an artwork.
"Joconde" is scrawled in a faded black flourish on the back of "The Mona Lisa", close to arrows pointing up to show which is the top. A small red triangle painted on the backs of the Dutch masters is a sign that in war time they are part of a priceless cultural heritage which must be saved first.
A bevvy of stickers from the world's top museums, The Tate Gallery, the Centre Georges Pompidou and the Guggenheim, traces the exhibitions which "The Smokers" by Fernand Leger painted in 1911-1912 has been part of.
- Mapping history -
"The front of the painting tells of the intention of preserving a moment forever," Muniz said. "The image is supposed to last exactly the way it is for millennia to come."
"The back of the painting tells the story of changing. It's where the painting has been."
The Mauritshuis gave Muniz -- renowned for his eclectic art works often in unusual medium such as chocolate, rubbish or sugar -- unparallelled access to its most iconic works from the Dutch Golden Age and he and his team have created five new reproductions.
Joining "Pearl Earring" and "The Anatomy Lesson", are Vermeer's "View of Delft" and "The Goldfinch" by Carel Fabritius, as well as Frans Post's "View of Itamarca Island in Brazil".
For future projects, Muniz is already eyeing Gustav Klimt's "The Kiss" hanging in Vienna, and Edvard Munch's "The Scream" -- which in an added challenge has another painting on its back.
For Mauritshuis paintings conservator Abbie Vandivere it was an exciting moment when "Pearl Earring" came off the wall -- something which doesn't happen often.
"But you can't tell from the back that there's this very famous painting on the front," she laughed.