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)

Firefighters work to quell a fire on an alleged clandestine gasoline storage in the Ixtlahuaca community, Mexico on January 5, 2016. Looting broke out at dozens of stores in Mexico on Wednesday on the sidelines of protests against a steep gasoline price increase as authorities detained more than 200 people. (Photo by Mario Vazquez de la Torre/AFP Photo)

Lukas Irmler balances on a 800 meter long highline 200 meters above Segnesboden, on Friday, June 28, 2019, in Flims, Switzerland. The highline is Switzerland's longest and will be set up untill Sunday in the Sardona World Heritage Region. (Photo by Gian Ehrenzeller/Keystone via AP Photo)

Bahamas' Shaunae Miller-Uibo celebrates winning the women's 200 meters final at the Diamond League Birmingham Grand Prix in Birmingham, Britain on August 18, 2019. (Photo by Jason Cairnduff/Action Images via Reuters)

Vladimir Mogilnikov, 62, washes his hands in a communal washing room in a dormitory for the workers of Proletarka textile factory in the town of Tver, 200 kilometres north-west from Moscow on August 8, 2020. (Photo by Andrey Borodulin/AFP Photo)

People cool off in Crown Fountain in Millennium Park on August 12, 2021 in Chicago, Illinois. As temperatures climb across the nation, nearly 200 million Americans are under some level of heat advisory. (Photo by Scott Olson/Getty Images)