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)

In this Thursday, November 1, 2018, photo, a girl uses a hammer to crack open shells for edible seeds to sell as snacks in Yangon, Myanmar. A United Nations report says some 486 million people are malnourished in Asia and the Pacific, and progress in alleviating hunger is stalling. (Photo by Thein Zaw/AP Photo)

A girl walks past destroyed houses at Basara refugee camp in Sittwe on May 16, 2023, after cyclone Mocha made a landfall. The death toll in cyclone-hit Myanmar's Rakhine state rose to at least 41 on May 16, 2023, local leaders told AFP. (Photo by Sai Aung Main/AFP Photo)

Iranian school girls show their hands with pro-government slogans and an anti-Israeli slogan which reads in Farsi: “Death to Israel”, during a rally in front of the former U.S. Embassy in Tehran, Iran, marking 44th anniversary of the seizure of the embassy by militant Iranian students, Saturday, November 4, 2023. (Photo by Vahid Salemi/AP Photo)

A girl dives under a wave at Bondi Beach as temperatures reached 29 degrees celsius on December 17, 2020 in Sydney, Australia. The Bureau of Meteorology predicted the arrival of thunderstorms and showers later today with a southerly change bringing possible severe storms around the Sydney region. (Photo by Mark Evans/Getty Images)

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)