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 girl washes the body paint off her arm on the shore of Lake Balaton during the coinciding Strand Festival and B.My.Lake Festival in Zamardi, 110 kms southwest of Budapest, Hungary, 24 August 2016. (Photo by Zoltan Balogh/EPA)

A girl poses at an entrance of her house next to a bomb dropped by the U.S. Air Force planes during the Vietnam War, in the village of Ban Napia in Xieng Khouang province, Laos September 3, 2016. From 1964 to 1973, U.S. warplanes dropped more than 270 million cluster munitions on Laos, one-third of which did not explode, according to the Lao National Regulatory Authority. (Photo by Jorge Silva/Reuters)

A woman and a girl dressed in historical Red Army uniform, wait before watching the Victory Day parade, marking the 71st anniversary of the victory over Nazi Germany in World War Two, at Red Square in Moscow, Russia, May 9, 2016. (Photo by Grigory Dukor/Reuters)

In this September 10, 2016 picture, a girl takes pictures of a fellow contestant while warming up backstage before competing in the Romania Miss Pole Dance Contest, ahead of the finals of the Pole Sport&Fitness World Championship 2016 in Bucharest, Romania. (Photo by Vadim Ghirda/AP Photo)

Airmen and their Japanese dates “do” the town together, visiting the local points of interest. Almost every community in Japan has it's famous shrines and parks. Tachikawa boasts beautiful environment. Girls are wearing western dress, May 1952. (Photo by National Archives and Records Administration)

An Indian girl cries as a medical worker collect her swab sample for COVID-19 test at a rural health center in Bagli, outskirts of Dharmsala, India, Monday, September 7, 2020. India's coronavirus cases are now the second-highest in the world and only behind the United States. (Photo by Ashwini Bhatia/AP Photo)

Two girls dressed up for a night out in Newcastle, United Kingdom on November 01, 2020 – just hours after Boris Johnson's announcement. Johnson says the new measures will begin on Thursday and last until second of December. (Photo by North News and Pictures/The Sun)