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)

“Mr. Brainwash (“MBW”) is a pseudonym for Thierry Guetta. According to the Banksy directed film Exit Through the Gift Shop, Guetta is a French citizen who now lives in Los Angeles, having been a proprietor of a clothing store and videographer who evolved into a street artist and gallery artist, influenced by the street artists he documented through video over the years. According to the film, Guetta was first introduced to street art by his cousin, the French street artist, Invader”. – Wikipedia

Photo: Artist Mr. Brainwash stands with his paintings “The Queen” (R) and “Kate Moss” at the Opera Gallery on October 3, 2011 in London, England. Works by pop artist and film maker Thierry Guetta, known as Mr. Brainwash, are on display at the gallery from October 6th to 31st, 2011. (Photo by Peter Macdiarmid/Getty Images)

“HA Schult, born Hans-Jürgen Schult on June 24, 1939 in Parchim, Mecklenburg is a German installation, happening and conceptual artist known primarily for his object and performance art and more specifically his work with garbage”. – Wikipedia

Photo: German artist Ha Schult stands with his “trash people” below the pyramids May 15, 2002 in Giza, Egypt. Inspired by the statues of the terracotta army of Chinese Emperor Quin Shi Huangdi (247–206 B.C.), the thousand piece sulpture has stood in Red Square in Moscow, La Defense in Paris and the Great Wall in China. Schult, born in 1939 wants to bring the “trash war” to the world's attention beause trash is the greatest battle facing mankind. (Photo by Norbert Schiller/Getty Images)

Have you ever been interested in the sign language? Surely you’ve always wanted to learn the art of sending a message using just your hands. To help people achieve this goal, Alex Solis has taken a photo of a hand showing each letter of the alphabet. However, this has been done many times before, which is why Alex decided to make each of the photos more interesting by placing little drawn animals and creatures onto each photo. Thanks to these cute little drawings the pictures become very endearing and memorable. All the little creatures blend in seamlessly into the pictures thanks to their well-chosen poses. This project, created by Alex Solis, is very unique and useful, allowing anyone to quickly remember all the listed hand gestures. (Photo by Alex Solis)

“As is probably stated somewhere in the theory of infinity, if you give an infinite amount of monkeys an infinite number of old-timey Polaroid cameras, one will eventually take “artistic” blurry photos of historical sites in Moscow which will then be auctioned at Sotheby's for an estimated $75,000 – $100,000. Fortunately for every simian art fan with a spare $100k, we are currently living in the very universe in which that concept is reality. Eighteen photographs by – and of – Mikki The Chimpanzee are going to auction on June 5, 2013”. – Callie Beusman via Jezebel.com. (Photo by Guzelian)

Manu Brabo was born in Spain in 1981. After studying Photography in The School of Arts and Crafts in Oviedo, he moved to Madrid where he started Journalism in Carlos III University while he was working as a photographer for several humble newspapers and agencies. In 2011, Manu was held captive and then released by by Libyan forces. Brabo, along with fellow AP photographers were awarded the 2013 Pulitzer Prize for Breaking News Photography. Here: a Syrian man cries while holding the body of his son, killed by the Syrian Army, near Dar El Shifa hospital in Aleppo, Syria, Wednesday, October 3, 2012. (Photo by Manu Brabo/AP Photo)