A man carrying vegetables is stopped by police at a barricade on a road during a 21-day nationwide lockdown to limit the spreading of coronavirus disease (COVID-19) in Chennai, India, March 25, 2020. (Photo by P. Ravikumar/Reuters)

Noah, 10, cools himself off in his garden during hot weather in Hertford, Britain, June 25, 2020. The UK is experiencing a summer heatwave, with temperatures in many parts of the country expected to rise above 30°C and weather warnings in place for thunderstorms at the end of the week. (Photo by Andrew Couldridge/Reuters)

The Aurora Borealis (Northern Lights) is seen in the sky in Ivalo of Lapland, Finland on September 27, 2019. (Photo by Alexander Kuznetsov/Reuters)

A replica of pre-historic drawings showing horses, rhinoceros and aurochs is seen on a wall during a press visit at the site of the Cavern of Pont-d'Arc project in Vallon Pont d'Arc April 8, 2015. The Cavern of Pont-d'Arc project is a replica of the pre-historic Decorated Cave of Pont-d'Arc known as Grotte Chauvet, in Vallon Pont-d'Arc in the Ardeche region, containing the world's earliest known art which was recently named a UNESCO World Heritage site. The facsimile cavern, which condenses some 8000m² of the original site into 3000m², will display faithful reproductions of paintings and engravings and will be inaugurated on April 10 and will open to the public on April 25. (Photo by Robert Pratta/Reuters)

Commuters ride on the roof of a Jakarta state rail train at Cawang train station on January 27, 2012 in Jakarta, Indonesia. (Photo by Ulet Ifansasti/Getty Images)

The electronically animated giant baby Miguelin (created by Isabel Coixet in collaboration with the special effects team behind Alien vs. Predator) was seen in the Spanish Pavilion at the site of Shanghai 2010 World Expo on April 27, 2010 in Shanghai, China. (Photo by China Photos)

Aerobatic aircrafts fly during a performance at the Airshow Zhengzhou 2017 in Zhengzhou, capital of central China's Henan Province on April 27, 2017. The 5-day air show kicked off in Zhengzhou on Thursday, aiming to build a general aviation gathering center for business and communications. (Photo by Li An/Xinhua via ZUMA Wire)

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)