A woman dressed as a nurse sits next to Gerhard after a coronavirus disease (COVID-19) vaccination in a brothel in Vienna, Austria on November 8, 2021. (Photo by Leonhard Foeger/Reuters)

Children dressed as Santa Clause play with a soccer ball as they celebrate at their school ahead of Christmas in Chennai on December 23, 2021. (Photo by Arun Sankar/AFP Photo)

People dressed in traditional costumes sing Christmas carols as they gather to celebrate Orthodox Christmas at a compound of the National Architecture museum in Kyiv, Ukraine on January 7, 2022. (Photo by Valentyn Ogirenko/Reuters)

A participant dressed up in a costume attends the 2021 Prague Comic Con in Prague, Czech Republic, October 16, 2021. (Photo by David W. Cerny/Reuters)

Children dressed as chess pieces perform during an event organised ahead of the 44th Chess Olympiad 2022, in Chennai on July 26, 2022. (Photo by Arun Sankar/AFP Photo)

An attendee dressed as Winnie the Pooh talks with a member of the D.C. Metropolitan Police Department during the annual pre-Halloween High Heel Race in Washington, D.C., U.S., October 28, 2025. (Photo by Nathan Howard/Reuters)

Mariam, a 9-year-old girl, carries her brother as she stands with other children at an underground ancient cemetery in Jabal al-Zawiya in the southern countryside of Idlib November 26, 2014. Residents are using ancient caves and cemeteries as underground shelters to hide in during shelling from forces loyal to President Bashar al-Assad. Picture taken November 26, 2014. (Photo by Khalil Ashawi/Reuters)

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)