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)

This adorable gallery reveals the astonished expressions of dozens of puppies as they try to gobble up treats flying through the air toward them. Photographer Christian Vieler, 48, has been documenting pooches, with their eyes bulging, mouths wide open and looks of love on their faces, in his studio as part of the project “Dogs Catching Treats” since 2013. (Photo by Christian Vieler/Caters News Agency)

Bex Hetherington exhibits a T-shirt at the Edinburgh College of Art degree show on June 8, 2011 in Edinburgh, Scotland. Students work will be exhibited across the campus buildings turning Edinburgh College of Art into the city's biggest gallery space. The work ranges from conceptual to commercial with inspirational influences as diverse and wide ranging as fashion photography, volcanoes, the crazy lady who put a cat in a bin, fairytales, the star system and serial killers. (Photo by Jeff J Mitchell/Getty Images)

Like a scene from a fantasy movie, a dilapidated room that appears to have been literally ripped out of a building remains suspended in mid air above Nantes, France. Its walls were torn apart, revealing bricks below the plaster, and wood floors reveal the joists inside. The floating room is accessible via a ladder. The gravity defying surreal installation is the work of Argentinean artist Leandro Erlich. The large-scale piece, called “Monte-meubles – L’ultime déménagement” (literally - The Furniture Lift – The Ultimate Moving Out), was created for the biannual Le Voyage a Nantes, an art festival which turns the entire French city into an art gallery.

Jewelry from packaging: Yoav Kotik’s rings, bracelets, necklaces and pendents are made from metal bottle caps. Yoav Kotik, the designer of "Precious metal" jewellery line, is a graduate of the "Bezalel academy of art and design" in Jerusalem. Yoav is a member of the Zik group. He frequently leads Master classes in the field of sculpture and design in recycled materials in academic institutes such as the "Shenkar academy of design" the "Bezalel academy" and the "Wizo academy". His works were presented in galleries across Israel, the UK, the Netherland and Japan.

Chinese artist Zhou Jie takes a nap on an unfinished iron wire bed, one of her sculpture works, after lunch at Beijing Now Art Gallery, in Beijing August 11, 2014. Zhou started her art project titled “36 Days” on August 9, in which she would live inside an exhibition hall with an unfinished iron wire bed, some iron wire sculptures in the shape of stuffed animal dolls, a certain amount of food and her mobile phone, for 36 days. The entire process is open to visitors and she may also interact with them, according to Zhou. (Photo by Jason Lee/Reuters)

This photographer has made it her mission to change people’s perception of pigeons – focusing on some of the most beautiful of the more than 300 species found globally. Rather than focus on the gray, nondescript birds people usually associate with the term “pigeon”, Leila Jeffreys has instead decided to snap the more vibrant varieties. Whether it be the wompoo pigeon, with its deep purple breast and green wings, or the rose-crowned fruit dove, with its pink head, Jeffreys, 46, gives the birds the same attention she would give a human model. (Photo by Leila Jefferies/Caters News Agency)