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 woman weeps after an announcement that Thailand's King Bhumibol Adulyadej has died, at the Siriraj hospital in Bangkok, Thailand, October 13, 2016. Thailand's Royal Palace says King Bhumibol, the world's longest-reigning monarch, has died at age 88. (Photo by Athit Perawongmetha/Reuters)

In this photo provided by Jean Revillard, Solar Impulse 2, a plane powered by the sun's rays and piloted by Andre Borschberg, approaches Kalaeloa Airport near Honolulu, Friday, July 3, 2015. His 120-hour voyage from Nagoya, Japan broke the record for the world's longest nonstop solo flight, his team said. (Photo by Jean Revillard/Global Newsroom via AP Photo)

A participant attempts to control his craft during the Red Bull Flugtag Russia 2015 competition in Moscow, Russia, July 26, 2015. Enthusiasts competed in disciplines on the longest distance of the flight, on the creativity of self-made aircrafts and on the originality of the performance in an attempt to win the contest, according to organizers. (Photo by Sergei Karpukhin/Reuters)

Thailand's King Bhumibol Adulyadej in serious portrait January 01, 1960. Thailand's Royal Palace said on Thursday, October 13, 2016, that Thailand's King Bhumibol Adulyadej, the world's longest-reigning monarch, has died at age 88. (Photo by John Dominis/The LIFE Picture Collection/Getty Images)

The Öresund or Øresund Bridge is a double-track railway and dual carriageway bridge-tunnel across the Øresund strait between Scania (southernmost Sweden) and Denmark. The bridge runs nearly 8 km (5 miles) from the Swedish coast to the artificial island of Peberholm, which lies in the middle of the strait. The remainder of the link is by a 4 km (2.5 mile) tunnel from Peberholm to the Danish island of Amager. The Øresund Bridge is the longest combined road and rail bridge in Europe, and connects two major metropolitan areas: Copenhagen, the Danish capital city, and the major Swedish city of Malmö. It connects the road and rail networks of Scandinavia with those of Central and Western Europe.

Bam Bam makes a fan feel his sweaty chest at Johnson' s Station in Picayune, Ms., on February 11, 2018. The Micro Wrestling Federation is a full scale, WWE type event sporting an entire cast under five feet tall. Founded in 2000, the MWF is the longest running organization within the Little Person wrestling industry according to its manager. (Photo by Emily Kask/AFP Photo)

A man wearing a Guy Fawkes mask enjoys a ride on a 350-meter (1148 feet) long water slide during 2015 City Silde Festa in central Seoul, South Korea, July 19, 2015. A 350 meter-long waterslide has been installed in downtown of Seoul, the longest waterslide to be recorded in Korea, according to local media. (Photo by Kim Hong-Ji/Reuters)