We had to begin with the man who put optical illusions on the map, M.C. Escher. \r\n\r\nEscher was not a formal mathematician by any means (he only had a high school education in the subject), but he was fascinated by the visual identity of mathematical concepts. Working mostly in lithographs and woodcuts, Escher explored the relationships between shape and space, interlocking figures in multi-dimensional planes and eternally spiraling spaces. In \"Relativity,\" one of Escher\'s most famous works, several identical, egg-headed characters are depicted roaming up and down endless staircases that seem to defy the laws of gravity.\r\n\r\nImage courtesy of Taschen Books.
(02 of07)
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Cloud Gate, the 110-ton elliptical sculpture created by Anish Kapoor, is currently installed in Chicago\'s Millennium Park. Formed from polished stainless steel plates, onlookers see a distorted reflection of their surroundings on their structure as their image is reflected back from varying perspectives.\r\n\r\n(Photo credit EMMANUEL DUNAND/AFP/Getty Images)
(03 of07)
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This acrylic painting by Japanese artist Makoto Aida deceives the eye. Titled AZEMICHI (a path between rice fields), the viewer looks down the evenly parted hair of a pig-tailed girl and sees a narrow country road, bordered by tall grass.\r\n\r\nImage courtesy of Mizuma Art Gallery
(04 of07)
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Japanese student Chooo-San takes body paint to the extreme with her doodles-turned-optical illusions.\r\n\r\nThe DIY aesthetic of her photographs mixed with her Surrealist body mutations look like a cross-pollination between a Facebook timeline and Pan\'s Labyrinth. Although the mind-bending body alterations look digitally made, she only uses acrylics.\r\n\r\nImage courtesy of Chooo-San
(05 of07)
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At the Guggenheim museum in Venice, a three-sided glass structure in a courtyard draws in visitors because of its mirrored edges. The reflective glass doubles objects or people seen on the opposite side of the installation when viewed from a particular angle.\r\n\r\n(Image via Flickr)
(06 of07)
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A Flickr user photographed this mind-boggling optical illusion during an art exhibition on the National Mall in Washington, D.C. Although the cartoon-esque house by Roy Lichtenstein appears to have four walls and a door, it\'s actually created by three angled surfaces as seen in this video that walks the viewer around the sculpture.\r\n\r\n(Image via Flickr)
(07 of07)
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A visitor walk along the piece of art called \"Down The Rabbit Hole\" by Rasch at the Arts Decoratifs museum in Paris, during the exhibition \"Trompe l\'Oeil.\" The art technique used in the piece uses extremely realistic imagery in order to create an optical illusion so the depicted objects appear in three dimensions. Four hundred pieces are presented in the exhibition which runs from February 2, 2012 till November 15, 2013.\r\n\r\n(Photo credit FRANCOIS GUILLOT/AFP/Getty Images)