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 Hindu devotee performs a stunt with fire during a rehearsal for the annual Rath Yatra, or chariot procession, which commemorates a journey by Hindu god Jagannath, his brother Balabhadra and sister Subhadra, in specially made chariots, in Ahmedabad, India, June 26, 2016. (Photo by Amit Dave/Reuters)

A man lays in front of a tank in the entrance to Istanbul's Ataturk airport, early Saturday, July 16, 2016. Members of Turkey's armed forces said they had taken control of the country, but Turkish officials said the coup attempt had been repelled early Saturday morning in a night of violence, according to state-run media. (Photo by Ismail Coskun/IHA via AP Photo)

In this Thursday, March 28, 2019, photo, a “golden giant burger” is served at a restaurant of Hotel Grand Hyatt Tokyo in Tokyo. The $900 wagyu (Japanese-produced beef) burger was unveiled to commemorate the era change. What’s in a name? Quite a lot if you’re a Japanese citizen awaiting the official announcement Monday, April 1, 2019 of what the soon-to-be-installed new emperor’s next era will be called. It’s a proclamation that has happened only twice in nearly a century, and the new name will follow Emperor Naruhito, after his May 1 investiture, for the duration of his rule, attaching itself to much of what happens in Japan. (Photo by Kyodo News via AP Photo)

Newly-wed Syrian couple Nada Merhi, 18, and Hassan Youssef, 27, have their wedding pictures taken in front of a heavily damaged building in the war ravaged city of Homs on February 5, 2016. A Syrian photographer thought of using the destruction of Homs to take pictures of newly wed couples to show that life is stronger than death. (Photo by Joseph Eid/AFP Photo)

School children dressed in traditional attire eat breakfast before participating in a Republic day parade in Bangalore, India, Thursday, January 26, 2017. (Photo by Aijaz Rahi/AP Photo)

Military items for women are seen in a store in Erbil, Iraq January 24, 2017. (Photo by Marius Bosch/Reuters)

Bonobo apes, primates unique to Congo and humankind's closest relative, groom one another at a sanctuary just outside the capital Kinshasa, Congo on October 31, 2006. (Photo by Finbarr O'Reilly/Reuters)