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 view of one of the dioramas contained inside iron boxes as part of the “S.A.C.R.E.D” installation by Chinese artist Ai Weiwei during a media preview at the cathedral in Cuenca, Spain, July 21, 2016. Ai Weiwei has reproduced scenes of his incarceration for a new art installation, a series of almost life-size dioramas – encased in steel boxes – showing his life in jail. (Photo by Susana Vera/Reuters)

Normally, pictures can be worth a thousand words but these images of some horrifyingly brilliant face paint art will give you the shivers. The fascinating photographs will make your head spin and your stomach churn as the life-like illustrations leave you shocked. Nikki Shelley, 34, from Rugby in Warwickshire, has built a career out of face painting after she started practicing on her children. Here: The Devil inside by Nikki Shelley. (Photo by Nikki Shelley/Caters News)

In this March 15, 2012 file photo, a Chinese woman poses for photos near a sculpture depicting a Chinese yuan note at an art district in Beijing, China. China devalued its tightly controlled currency on Tuesday, August 11,2015, following a slump in trade, triggering the yuan's biggest one-day decline in a decade. The central bank said the yuan's 1.3 percent fall was due to a change aimed at making its exchange rate controls more market-oriented. But any change raises the risk of tensions with China's trading partners. (Photo by Ng Han Guan/AP Photo)

This graceful husky appears to be smarter than your average dog having apparently mastered the art of walking on water. The soft-footed canine was photographed while making its way across a lake in northern Russia. Photographer Fox Grom captured a remarkable set of images after heavy rain fell on a frozen lake to create the amazing illusion. The 40-year-old, who works as an all-terrain vehicle driver, regularly walks his pet dogs, Alaska and Blizzard, near the natural beauty spot. “I always take pictures of my dogs whilst walking them but on this occasion there was an extraordinary phenomenon“, he said. “The ice was already very thick when it rained heavily making for a spectacular scene”. Here: Husky dog Alaska walks on water in Northern Russia, January 2015. (Photo by Fox Grom/Visual Press Agency)

Neapolitan Christmas Nativity figurines on display at “Maestri Ferrigno”, which opened in 1836, at Via San Gregorio Armeno on December 14, 2011 in Naples, Italy. Via San Gregorio Armeno, Christmas Alley as it is known, is considered by many to be the world capital of the Nativity and home to the artisans and merchants who specialize in the art and the craft of the Neapolitan Presepe. Over the Christmas period, more than half a million tourists come to see the shops. (Photo by Franco Origlia/Getty Images)

Ron Mueck's “Big Baby” sculpture appears to look round at Jenny Saville's painting “Interfacing” at the Masterpieces Exhibition at Christie's on June 13, 2011 in London, England. The painting and sculpture feature in the exhibition, open to the public from 13th–15th June 2011, which showcases some of the Ј250 million worth of art for sale over the next four weeks. Artists including Michelangelo, Gainsborough, Goya, Stubbs, Monet, Picasso and Renoir are represented. (Photo by Peter Macdiarmid/Getty Images)

Cosplay enthusiasts Alex Lawson, 20, attends the North East Manga and Anime Convention (NemaCon) dressed as Hunni Sempai at Middlesborough Town Hall on June 18, 2011 in Middlesbrough, England. Hundreds of Manga, Anime and Cosplay enthusiasts gathered for NemaCon 2011. Cosplay is short for Costume Play where players dress and perform roles from Japanese culture, Anime and Manga art characters. Many subcultures have also evolved inspired by video games, American cartoons and comics. (Photo by Christopher Furlong/Getty Images)