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)

Hundreds of colourful pumpkins and squash create an extraordinary rainbow scene at a vegetable wholesale market in Bangladesh on August 1, 2019. A seller sits among his vibrant wares which are produced by farmers from local villages. (Photo by Abdul Momin/Solent News)

A glitter rainbow mini dress, worn by Taylor Swift in her “End Game” music video, and other outfits in the William Morris Gallery in London, United Kingdom on March 31, 2023 unveils an exhibition of fashion designer Ashish. (Photo by Guy Bell/Alamy Live News)

Bangladeshi children from Khan Tea garden posing for photos on March 23, 2022 with their faces painted after adorning with colors like Rainbows on the celebration of the annual Hindu festival of colors, known as Holi festival marking the onset of spring. (Photo by Md Rafayat Haque Khan/Eyepix Group/Rex Features/Shutterstock)

Revelers jump on a rainbow painted crosswalk in Church Street, Toronto's LGBT neighbourhood, before “WorldPride”, a gay pride parade, in Toronto, June 29, 2014. Toronto is hosting WorldPride, a week-long event that celebrates the lesbian, gay, bisexual and transgender (LGBT) community. (Photo by Mark Blinch/Reuters)

Walkers marvel at a fog bow over Curbar Edge, Derbyshire in the last decade of October 2023. The phenomenon is similar to a rainbow, but because the water droplets that cause fog are so small, its colours are very weak. (Photo by Richard Bowring/Animal News Agency)

A six-year-old acrobat performs on the opening of a tourist festival in Bozhou, Anhui province, China May 3, 2015. (Photo by Reuters/China Daily)