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 passenger plane, with a full Harvest moon seen behind, makes its final landing approach towards Heathrow Airport in London, Britain, October 5, 2017. (Photo by Toby Melville/Reuters)

An Amur tiger walks across a passageway after a news conference at the Philadelphia Zoo, Wednesday, May 7, 2014, in Philadelphia. The see-through mesh pathway called Big Cat Crossing is part of a national trend called animal rotation that zoos use to enrich the experience of both creatures and guests. (Photo by Matt Slocum/AP Photo)

Police women ride Segways as they patrol at Guangzhou South Railway Station on Jaunary 4, 2012 in Guangzhou, China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

A view of the Hazelwood Power Station across the cooling pondage at sunrise on March 21, 2012 in Melbourne, Australia. The brown coal fueled power station, located in Latrobe Valley is the oldest in Victoria and provides the state nearly 25% of its energy. In 2005 Hazelwood was labeled Australia's least carbon efficient power station by WWF Australia and continues to be a target of issue of environmentalist groups. (Photo by Hamish Blair/Getty Images)

A Soyuz capsule carrying International Space Station (ISS) crew members U.S. astronaut Scott Kelly, Russian cosmonauts Sergei Volkov and Mikhail Korniyenko descends beneath a parachute near the town of Dzhezkazgan (Zhezkazgan), Kazakhstan, March 2, 2016. (Photo by Kirill Kudryavtsev/Reuters)

Sabine Pearlman‘s photographs find beauty in the destructive engineering of ammunition with this series of cross-sections of bullets cartridges from a Swiss bunker. They reveal the complexity inside each case. This series, which consists of 900 specimens, was photographed inside a WWII bunker in Switzerland. Pearlman says that she is intrigued by the beautiful complexity of the ammo set against its destructive purpose, at once showing off humanity’s ability to create and destroy.

Typhoon Bopha moves toward the Philippines, observed from the ISS, on December 2, 2012. (Photo by AP Photo/NASA via The Atlantic)