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)

Hugo Belleri (L), a three-year-old boy and the youngest Gilles of Binche, takes part in the parade of Young Gilles of Binche during the carnival event in Binche February 17, 2015. The Binche carnival, a UNESCO World Heritage event, is the biggest and the liveliest annual event in Belgium. Up to 1,000 Gilles parade in the city centre of Binche, wearing a red, yellow and black medieval costume hung with bells and decorated with fluffy lace at the neck, wrists and ankles. (Photo by Yves Herman/Reuters)

Pilgrims lift up their dresses as they cross the Quema river during the annual El Rocio pilgrimage in Villamanrique, near Sevilla on June 1, 2017. El Rocio pilgrimage is the largest in Spain with hundreds of thousands of devotees wearing traditional outfits converging in a burst of colour as they make their way on horseback and decorated carriages across the Andalusian countryside. (Photo by Cristina Quicler/AFP Photo)

A colourful morning sunrise on Christmas Eve at Victoria Tower on Castle Hill, West Yorkshire, England on December 24, 2017. The history of human activity on the Castle Hill goes back over 4000 years. The site was developed as an iron age hill fort, surrounded by defensive ditches and ramparts. In the Middle Ages there was a castle on the hill, of which the well remains. The present tower was built to commemorate Queen Victoria's Diamond Jubilee of 1897. (Photo by Charlotte Graham/ZUMA Wire/Rex Features/Shutterstock)

Revellers dressed as the Devil take part in a parade to celebrate Saint Nicholas Day (Mikulas) in Prague, Czech Republic on December 5, 2022. Meeting Saint Nicholas, the Aangel, and the Devil, who talk to children and reward those who have behaved well during the year with small presents, is tradition in the Czech Republic before the Christmas holidays. (Photo by Michal Cizek/AFP Photo)

Britney Spears supporter Phoebe Price and her dog Henry take pictures next to a “Free Britney” Christmas tree set by fans outside a hearing concerning the pop singer's conservatorship at the Stanley Mosk Courthouse, Friday, November 12, 2021, in Los Angeles. A Los Angeles judge ended the conservatorship that has controlled Spears' life and money for nearly 14 years. (Photo by Damian Dovarganes/AP Photo)

Ayaka Oshita, a 27-year-old diver, practices in preparation for the upcoming seasonal feeding performance as a Santa diver at Sunshine Aquarium at Ikebukuro in Tokyo, Japan, 07 December 2021. Oshita has 15-month experience for feeding fish at the aquarium after she joined the aquarium in 2019. The Santa diver performance will be held for three days around the Christmas time. The aquarium will not inform the performance time to avoid the visitors' crowd due to the COVID-19 pandemic. (Photo by Kimimasa Mayama/EPA/EFE)