A man passes by an unfinished street art graffiti made in a stairway by French street artists Zag and Sia in Paris on March 1, 2016. The two artists drew inspiration from famous “Liberty Leading the People” (La Liberte guidant le peuple) painting by French Eugene Delacroix commemorating the July Revolution of 1830 and viewed as a symbol of the French Republic. (Photo by Joel Saget/AFP Photo)

Friends and relatives mourn by the coffin during the wake for Florjohn Cruz, who was killed in a police drugs buy-bust operation, in Manila, Philippines late October 20, 2016. (Photo by Damir Sagolj/Reuters)

Japanese artist Megumi Igarashi, known as Rokudenashiko, holds her artwork after a news conference following a court appearance in Tokyo April 15, 2015. A Japanese artist on trial for obscenity after making figurines and a kayak modeled on her v*gina said on Wednesday that there was nothing wrong with her artwork and her arrest merely showed how far Japan remains behind the west. Words in the artwork read “Centre. 3D scan”. (Photo by Toru Hanai/Reuters)

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)

Tiharu Ram, 70, a follower of Ramnami Samaj, who has tattooed the name of the Hindu god Ram on his face, poses for a picture outside his house in the village of Chandlidi, in the eastern state of Chhattisgarh, India, November 16, 2015. Denied entry to temples and forced to use separate wells, low-caste Hindus in the eastern state of Chhattisgarh first tattooed their bodies and faces more than 100 years ago as an act of defiance and devotion. (Photo by Adnan Abidi/Reuters)

“Slow”. A calm cow in the messy streets of Jodhpur. Photo location: India. (Photo and caption by Matthias Troeger/National Geographic Photo Contest)

Talk-show host Oprah Winfrey interviewing cyclist Lance Armstrong during taping for the show "Oprah and Lance Armstrong: The Worldwide Exclusive" in Austin, Texas. The two-part episode of "Oprah's Next Chapter" will air nationally Thursday and Friday, Jan. 17-18, 2013. (AP Photo/Courtesy of Harpo Studios, Inc., George Burns)

Photos of Edward Snowden, a contractor at the National Security Agency (NSA), and U.S. President Barack Obama are printed on the front pages of local English and Chinese newspapers in Hong Kong in this illustration photo June 11, 2013. Snowden, who leaked details of top-secret U.S. surveillance programs, dropped out of sight in Hong Kong on Monday ahead of a likely push by the U.S. government to have him sent back to the United States to face charges. (Photo by Bobby Yip/Reuters)