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 has her helmet adjusted on the top of a tank during the Children's Day celebration at a military facility in Bangkok, Thailand January 9, 2016. Army barracks opened their doors to children to interact with their weapons and vehicles as part of the celebration. (Photo by Jorge Silva/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)

A school girl reacts as a health worker inoculates her with the dose of Pfizer-BioNTech vaccine against the Covid-19 coronavirus for the 12-15 years age group at an educational institution in Colombo on January 7, 2022. (Photo by Ishara S. Kodikara/AFP Photo)

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)

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)