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 view of one of the dioramas contained inside iron boxes as part of the “S.A.C.R.E.D” installation by Chinese artist Ai Weiwei during a media preview at the cathedral in Cuenca, Spain, July 21, 2016. Ai Weiwei has reproduced scenes of his incarceration for a new art installation, a series of almost life-size dioramas – encased in steel boxes – showing his life in jail. (Photo by Susana Vera/Reuters)

People are often fascinated by things that baffle them. For example, Livia Marin creates porcelain pottery that looks as if it has partially melted. This pottery might serve little purpose, yet it is definitely a curious thing to have in your house. This set of pictures shows off her “Nomad Patterns” series of deformed vases, pitchers, and teacups. The most appealing thing about these pieces of art is that the patterns on the “melted” parts are as beautiful as on the rest of the pottery. (Photo by Livia Marin)

All throughout history of mankind people were fascinated by time, its flow, and how to measure it. Thus, the science of horology can into being, as people invented more and more sophisticated ways of measuring the passage of time. Truly, it’s one of the most profound characteristics of being a human, to feel and to ponder the meaning of time, its properties, and will we ever be able to move through it, not with it. Now, however, horology is mainly referred to the art of mechanical watchmaking. (Photo by MB&F)

The pictures made by Elizabeth Gadd are so beautiful, tranquil, and mesmerizing, that they wash over your soul in a wave of sadness. The same sadness that you feel when hearing a wonderful piece of music. The same sadness that enters your soul when you worry to death about your loved one, but everything turns out to be just fine. These aren’t just pictures… The pieces of art that Elizabeth, a 21-year-old self-taught photographer makes, are windows into fairytales; portals into other dimensions. Works so surreal, that it makes you wonder if the scenes that you are seeing were actually shot on this planet; that they are not figments of Beth’s imagination. (Photo by Elizabeth Gadd)

The essence of the “masterpieces” created by Giuseppe Lo Schiavo is in taking a famous architectural landmark placing it on a rock, and making it float over some body of water. Well… that’s pretty much it. Of course there will be some people who will look deep within these works of art, and catch the true meaning and intentions of the mastermind who created them, and maybe even purchase them for unreasonable amounts of money. But the rest of us, the common folk, will stare at it for a while, cringe, and move on without a second thought. (Photo by Giuseppe Lo Schiavo)

Some people use paper as their canvas for creating works of art, Patrik Bundeli, on the other hand, uses Ping-Pong balls. His steady hand turns simple white balls into elaborate cartoonish faces. Some of his works feature black and white gothic visages, while others have adorable little snouts. The latter ones would make a wonderful addition to any working place, putting smiles on everyone’s faces. (Photo by Patrik Bundeli)

Redhead Day (Roodharigendag in Dutch) is the name of a Dutch summer festival that takes place each first weekend of September in the city of Breda, in the Netherlands. The two-day festival is a gathering of people with natural red hair, but is also focused on art related to the colour red. Activities during the festival are lectures, workshops and demonstrations which are aimed specifically at red-haired people. The festival attracts attendance from 50 countries and is free due to sponsorship of the local government.