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)

Chris Staring photographs a mysterious train graveyard in the heart of southern Bolivia, where the skeletons of British steam locomotives and rail cars rust away on the edge of the world’s largest salt flats. More than 100 rail cars and locomotives can be found in different states of decay in the train graveyard. (Photo by Chris Staring/Rex Features/Shutterstock)

First Lady Melania Trump kisses Canada's Prime Minister Justin Trudeau next to the President Donald Trump during the family photo with invited guests at the G7 summit in Biarritz, France, August 25, 2019. (Photo by Carlos Barria/Reuters)

These beautiful photos capture the tender moments between two young boys who share a unique bond with animals. Elena Shumilova, from Andreapol, Russia, began taking pictures of her sons Yaroslav and Vanya in early 2012 when she received her first professional camera. The pair were immediately accepted by the animals from a young age and their incredible bond continues to strengthen as they get older. Elena, 32, was able to capture images her boys playing with such animals as rabbits, dogs, cats and ducks as they become totally immersed in their communication with their furry friends. (Photo by Elena Shumilova)

A bride weeps in a mass wedding ceremony at the CheongShim Peace World Center in Gapyeong, South Korea, Wednesday, February 12, 2014. Some 2,500 South Korean and foreign couples exchanged or reaffirmed marriage vows in the Unification Church's mass wedding arranged by Hak Ja Han Moon, wife of the late Rev. Sun Myung Moon, the controversial founder of the Unification Church. (Photo by Lee Jin-man/AP Photo)

In a north London hospital, scientists are growing noses, ears and blood vessels in the laboratory in a bold attempt to make body parts using stem cells. It is among several labs around the world, including in the U.S., that are working on the futuristic idea of growing custom-made organs in the lab. (Photo by Matt Dunham/AP Photo)

Armed with only paper, graphite and coloured pencils – plus his vivid imagination – the artist creates remarkable drawings that leap from the page when photographed. The 32-year-old, from Alkmaar in Holland, began experimenting with anamorphic 3D drawing five years ago. Photo: Ramon Bruin’s 3D illustration of two twins drawing each other. (Photo by Ramon Bruin/Medavia)

When you look at the picture of a furry pig that resembles a sheep from a distance, you may think that this may be the result of the work of some crazy scientist that tinkered with the pig’s genome. However, in this case, this is not true. Mangalica is a natural breed of pigs, which were bred in Europe for their lard. This breed of pigs is very unique, since the only other breed of pigs which had a long coat was Loncolnshire Curly Coat, which is now extinct. In the past, these pigs were quite popular, since they were able to produce a lot of lard. However, when the demand for pig lard dwindled, the population of these pigs rapidly decreased, making it a “rare breed”.