New York City Deputy Police Commissioner John A. Leach, right, watching agents pour liquor into sewer following a raid during the height of prohibition, circa 1921. (Photo by Tom Marshall/Mediadrumworld)

Photochromes are vibrant and nuanced prints hand-coloured from black-and-white negatives. Created using a process pioneered in the 1880s, these images offer a fascinating insight into the world when colour photography was still in its infancy. A Tour of the World in Photochromes is at the Swiss Camera Museum, Vevey, until 21 August. Here: Street food in the Strada del Porto in Naples, Italy, 1899. (Photo by Swiss Camera Museum/The Guardian)

The sun shines on trees that are displaying their autumn colours surrounding Palladian bridge and the lakeside Pantheon at the National Trust's Stourhead on November 3, 2010 near Warminster, England. (Photo by Matt Cardy/Getty Images)

A toddler held by her father swims underwater during a swimming class for babies at Lane Cove pool February 16, 2007 in Sydney, Australia. (Photo by Ian Waldie/Getty Images)

Waves hit the seawall during heavy seas and high winds in Dawlish in south west Britain, February 2, 2017. (Photo by Toby Melville/Reuters)

Luxury buildings are reflected in front of houses at a lake dwelling also known as or palafitte or “Palafito” in Recife, Brazil, March 1, 2016. Zika has spread most rapidly in the urban squalor of Brazil's northeastern coastal cities like Recife. (Photo by Ueslei Marcelino/Reuters)

Hindu devotees perform rituals during the Bol Bom pilgrimage, on the outskirts of Kathmandu, Nepal, Monday, August 8, 2016. During this pilgrimage, devotees walk miles barefooted before offering water collected from Bagmati river, at the Pashupatinath temple in Katmandu. Shravan Somwar or Monday of Hindu calendar month of Shravan is considered auspicious for offering prayers to Lord Shiva, the god of destruction. (Photo by Niranjan Shrestha/AP 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)