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 woman takes a selfie in front of a Lunar New Year display featuring sheep at a shopping mall in Hong Kong, February 13, 2015. (Photo by Bobby Yip/Reuters)

Football transfers are not cheap. To have a player strengthen their ranks, teams are willing to pay big money. The football transfer considered to be the most expensive in the sport's history was that of Gareth Bale leaving Tottenham to play at Real Madrid. The Spanish club paid not less than £86 million (about $133 million at today's exchange rates) to have the player among its own. But recent news suggest that this record might be broken this year. According to reports in the media, UK Premier League team Manchester United is willing to almost double that amount.

Russian artist Maria Gazanova (L) works on her "The Alive Painting" art work during the Art Krasnoyarsk annual festival in Siberian city of Krasnoyarsk, Russia November 4, 2015. (Photo by Ilya Naymushin/Reuters)

The new EVR system which allows the recording of television programmes which can then be watched at the owner's discretion. The new Teleplayer has been produced in partnership with Rank Bush Murphy Ltd and EVR and has enormous potential. 21st September 1970. (Photo by Central Press/Getty Images)

A visitor visit the “12 Labors of Putin” art exhibition on October 6, 2014 marking the 60th birthday of Russia's President Vladimir Putin at the design workshop in Moscow. (Photo by Vasily Maximov/AFP Photo)

National Geographic invites photographers from around the world to enter the 2013 National Geographic Photography Contest. The grand-prize winner will receive $10,000 (USD) and a trip to National Geographic headquarters in Washington, D.C., to participate in the annual National Geographic Photography Seminar in January 2014. Photo: “We just want to move to search to the Leopard at that morning but we found a group of giraffes come toward a small lake and start drinking it was a nice moment when the Giraffe finish from drinking and leave a letters “S” with motion in the air”. (Photo and caption by Majed Ali/National Geographic Photography Contest)