For centuries the Highlands peoples of Papua New Guinea fought over land, women and pigs. Sorcery and battle skills could elevate a clan to Bigmanship, where the bigger the “presentation”, the bigger the man. Clans therefore would paint their bodies and create fearsome masks as part of their psy. Here: These are the terrifying tribe of “mudmen” from a remote part of Papua New Guinea. (Photo by Jeremy Hunter/Exclusivepix Media)

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 spooky sight to behold! This is what a psychiatric hospital that has been abandoned for years looks like. Complete with bowling alley and a theater, the hospital shows just how much nature has weathered it over time as paint peels from the walls and the mattress gather dust. Here: This area of the hospital was last used as a day care center in the early 2000s. (Photo by Will Ellis/Caters News)

Call Parade is an ongoing public art project in São Paulo sponsored by Brazilian telecommunications firm Vivo, that paired 100 artists with 100 street-side phone booths giving them free reign to transform the peculiar hooded fixtures into anything imaginable. The exhibition has proven to be extremely popular and Brazilian photographer Mariane Borgomani set out to capture a number of the phones, my favorite of which is the painted day/night treatment above by artist Maramgoní.

A man covered in motor oil, poses for a picture next to a girl dress a traditional clothes during a festivities in honor of Santo Domingo de Guzman in Managua, Nicaragua, Saturday, August 1, 2015. Some of the faithful coat their bodies in a black motor oil, red paint and wear traditional clothes as a promise for a prayer or miracle they believe was performed or answered by Managua's patron saint, Santo Domingo de Guzman. (Photo by Esteban Felix/AP Photo)

The great vector artist OG Abel was a diamond in the rough. Growing up in violent surroundings, OG Abel found shelter in art. With an unsupportive father who always told him artist die broke, his only creative activity was strongly connected to religion. Having a church-going mother, OG Abel says he would spend hour drawing images from the Bible, his favorite pictures being those of animals, especially lions. He would also study the elaborate paintings in churches, the architecture, and/or the sculptures.

Image patterning has existed for hundreds of years; however, before Thomas Yang no one has ever thought of putting paint on the bicycle wheels and using it as a patterning tool to create very interesting-looking pictures. Being an avid cyclist and an artist, Thomas Yang has decided to combine the two, creating the 100copies. The name of this project not only alludes to the fact that only one hundred copies of those pictures were going to be made, but also to the fact that the pictures themselves consist of hundreds of repeating shapes. And even though the project is called 100copies, no two pictures are alike due to the nature of their creation, making them truly unique. (Photo by Thomas Yang)

The Slauerhoffbrug (English: Slauerhoff Bridge) is a fully automatic bascule bridge (aka tail bridge) in the city of Leeuwarden in the Netherlands. It uses two arms to swing a section of road in and out of place within the road itself. It is also known as the “Slauerhoffbrug ‘Flying’ Drawbridge”. A tail bridge can quickly and efficiently be raised and lowered from one pylon (instead of hinges). This quickly allows water traffic to pass while only briefly stalling road traffic. The deck is 15 m by 15 m. It is painted in yellow and blue, representative of Leeuwarden's flag and seal.