Beneath the Swedish capital lies an intricate web of underground train lines. More than 90 of the 100 stations in the 110km tunnel system, sometimes referred to as “the world’s longest art gallery”, have been decorated with paintings, installations, mosaics and sculptures by 150 artists since the 1950s. After spending a couple of weeks exploring arctic Norway and Sweden, London-based travel photographer Conor MacNeill headed underground to capture images of the metro stations. Here: A rainbow arcs over a girl on the platform of Stadion station. (Photo by Conor MacNeill/The Observer)

A spooky sight to behold! This is what a psychiatric hospital that has been abandoned for years looks like. Complete with bowling alley and a theater, the hospital shows just how much nature has weathered it over time as paint peels from the walls and the mattress gather dust. Here: This area of the hospital was last used as a day care center in the early 2000s. (Photo by Will Ellis/Caters News)

My name is Chris Kapono and I am a self-taught artist living in Missouri. I have been drawing and painting ever since I can remember and art has been a big part of my life. My love of animals and nature is reflected in my art and sometimes interesting things I find on walks in the woods will find their way into some of my pieces!

The artwork of Giant Horse Aboriginal rock art galleries in the Quinkan Country is seen on June 19, 2011 in Laura, Australia. The ancient aboriginal rock art in this region is some of the largest and oldest in the world, dating back over 15,000 years. Paintings, stencil art and engravings cover thelands traditionally home to the Kuku, Yalanji, Guugu Yimithirr and Kuku Thaypan people. As a UNESCO-identified top 10 rock art site in the world, international travelers visit the area to learn and understand the aboriginal culture through the artwork. (Photo by Mark Kolbe/Getty Images)

A giant sculpture of a seven-month-old baby by artist Marc Quinn entitled “Planet” contrasts against the stately grandeur of Chatsworth House and the Derbyshire countryside on 4 September, 2008, Chatsworth, England. The bronze sculpture painted white is part of the Beyond Limits exhibition of modern and contemporary sculpture displayed in the gardens of Chatsworth by Sotherby's. More than 20 works will be on display from 9 September to 2 November 2008. In past years acclaimed artists Damien Hirst, Antony Gormley, Salvador Dali and Henry Moore have had work exhibited. (Photo by Christopher Furlong/Getty Images)

Using acrylic paint, 19-year old Japanese student and artist Chooo-San has transformed the bodies of herself and a handful of lucky volunteers into ones that appear to be from another planet. Bored with technology, she wanted to see how far she could go with creating eye-catching illusions in the real world, rather than relying on programs like Photoshop.

SEE ALSO: «A frightening-realistic Body Art by Chooo-San»

Korean artist Hyungkoo Lee has created a series (Homo Animatus) of works featuring skeletal representations of familiar cartoon characters. He uses resin, aluminum sticks, stainless steel wires, springs, and oil paint. If you look closely, you will see the bones of our favorite childhood friends like Canis Latrans Animatus (Wile E. Coyote), Geococcyx Animatus (Roadrunner), Lepus Animatus (Bugs Bunny), Felis Catus Animatus (Tom), Mus Animatus (Jerry), Anas Animatus (Donald Duck) and his three nephews, Animatus H, D and L ( Huey, Dewey and Louie)

The Art Car Parade is the highlight of a three-day celebration of the drive to create: Art Car Weekend. But it all began with a donated 1967 Ford staton wagon and $800 worth of paint and plastic fruit. And now, 26 years later, it attracts 250+ vehicles (and other entries) from 23 states, Canada, and Mexico. Photo: An art car is seen on Allen Parkway during the 26th Annual Houston Art Car Parade on May 11 in Houston, Texas. (Photo by Scott Halleran)