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)

Wildlife photographer Danté Fenolio has headed into areas untouched by sunlight – deep seas, caves and underground – and found creatures that are exploding with colour. Here: The golden harlequin toad has vanished from the wild, and only a small number live on in captivity. A fungus caused them, and many other amphibians, to die out in their home in Central America. (Photo by Danté Fenolio/The Guardian/Johns Hopkins University Press)

Giffords Circus’s show is touring the UK. Established in 2000, Giffords Circus is a small circus company that delivers circus / theatre fusion to the villages and market towns of the south west. It combines dance, comedy, horses and live music in a two-hour show, located on village greens in a small white tent surrounded by handmade burgundy and gold showman’s wagons. Photographer Tom Pilston goes behind the scenes to meet the performers. Here: The incredible, gravity-defying Konjowoch Troupe. (Photo by Tom Pilston/The Guardian)

These images of abandoned hospitals across Italy are not for the faint-hearted. Both of the hospitals featured in the photographs are Italian asylums – known as manicomios – that were used as mental hospitals. Shut down by law in 1978, the derelict buildings are visibly overgrown and make for very eerie portraits. Photographer Thomas Windisch, 32, of Graz, Austria, said the asylums, located in top-secret spots, can get very creepy when there aren't many people there with him. Here: a hallway within an abandoned hospital. (Photo by Thomas Windisch/Caters News)

These pictures show the beautiful ruins of abandoned temples. The incredible shots, taken at temples in Angkor, Cambodia, show the striking yet haunting temples as they crumble to ruins. While they may have lost some of their former glory, the stunning temples show the beauty of the Cambodian landscape through the historic architecture. Here: Sun rises over the 5 towers of Angkor. (Photo by Alex Teuscher/Caters News)

Normally, pictures can be worth a thousand words but these images of some horrifyingly brilliant face paint art will give you the shivers. The fascinating photographs will make your head spin and your stomach churn as the life-like illustrations leave you shocked. Nikki Shelley, 34, from Rugby in Warwickshire, has built a career out of face painting after she started practicing on her children. Here: The Devil inside by Nikki Shelley. (Photo by Nikki Shelley/Caters News)

From the rocks of Arnhem Land to the backyards of the Sydney suburbs, from stretching by the pool to waiting for evening prayer, snapshots for the 2015 Australian Life prize demonstrated a nation in colour and motion. Here: Children Cooling Off at Dhiari Homeland. Local children get wet and cool in Arnhem Land. (Photo by Matthew Abbott/Australian Life Prize 2015)

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)