Young girls attend a training session in MGFSO Olympic reserve school in Moscow on May 30, 2016. (Photo by Kirill Kudryavtsev/AFP Photo)

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 Tibetan nomad family crowds on a motorcycle at a camp for cordycep pickers on May 21, 2016 near Sershul on the Tibetan Plateau in the Garze Tibetan Autonomous Prefecture of Sichuan province. (Photo by Kevin Frayer/Getty Images)

A group of women laugh at artwork referencing U.S. Republican presidential candidate Donald Trump made by the artist Hanksy and being sold at a temporary store in New York, U.S., June 4, 2016. (Photo by Lucas Jackson/Reuters)

Participants dressed as characters such as elves, dwarves, goblins and orcs from the J.R.R. Tolkien's novel “The Hobbit” re-enact the “Battle of Five Armies” in a forest near the town of Doksy, Czech Republic, June 4, 2016. Several hundred people arrived in the forest to re-enact the famous battle from Tolkien's novel that was published for the first time in 1937. (Photo by David W. Cerny/Reuters)

Juanita Robinson (L) from Ohio and Trenaya Blackburn pose as Quan White from Michigan takes their picture as they vacation on South Beach on May 16, 2016 in Miami Beach, Florida. The Florida government announced it broke a tourism record in the first quarter of this year, attracting 29.8 million tourists, an increase of 4.8 percent over the same time frame in 2015. (Photo by Joe Raedle/AFP Photo)

Baker Magadma, a member of Palestinian sports group Bar Palestine, performs on the street in Gaza City, on June 3, 2016. Street workout, which is still new in Gaza, is a growing sport across the world with annual competitions and events. (Photo by Mohammed Abed/AFP Photo)

A man demonstrates outside Republican presidential candidate Donald Trump's news conference at Trump Tower in New York, U.S., May 31, 2016. (Photo by Shannon Stapleton/Reuters)