A woman sits on a terrace at Tiki hostel in Cantagalo favela, in Rio de Janeiro, Brazil, April 16, 2016. Hostels in a few of Rio's more than 1,000 slums serve not only as a cheap housing alternative for the more adventurous among the estimated 500,000 foreign tourists expected to arrive for the Olympics in August. The establishments also open up the rich culture of the city's shantytowns for travellers, giving them a glimpse into once “no-go” areas where about one-fifth of Rio's population lives. (Photo by Pilar Olivares/Reuters)

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)

A woman holds Kalashnikov assault rifle during a training session with members of the Georgian Legion, a paramilitary unit formed mainly by ethnic Georgian volunteers to fight against Russian forces in Ukraine in 2014, in Kyiv, Ukraine, Saturday, February 19, 2022. Separatist leaders in eastern Ukraine have ordered a full military mobilization amid growing fears in the West that Russia is planning to invade the neighboring country. The announcement on Saturday came amid a spike in violence along the line of contact between Ukrainian forces and the pro-Russia rebels in recent days. (Photo by Efrem Lukatsky/AP Photo)

Environmental activist Rob Greenfield walks around Beverly Hills, California on May 16, 2022 wearing a suit filled with every piece of trash he has generated living and consuming like a typical American for one month to raise awareness about how much garbage just one person generates. (Photo by Robyn Beck/AFP Photo)

Artists perform during a “Yandu Story” Show performance, in Yancheng, Jiangsu province, China, 20 September 2022. The story dates back to some 100 years when – according to the organizers – two prominent local families, Gu and Ling, were committed to get out of a predicament, but parted due to different development concepts and ended in a turmoil. The large-scale immersive series of performances took more than a year of careful planning and consists of two parts: a daytime performance and a 90-minute night performance, they added. (Photo by Alex Plavevski/EPA/EFE/Rex Features/Shutterstock)

A cosplayer dressed as a “remote worker” with “corporate slave” written on his glasses poses for a photo on New Year's Eve at Comiket, the largest comic market that had been postponed for two years because of the coronavirus disease (COVID-19) pandemic, in Tokyo, Japan December 31, 2021. (Photo by Androniki Christodoulou/Reuters)

Tupolev Tu-142MK, a Soviet and Russian maritime reconnaissance and anti-submarine warfare aircraft flies above a statue of Soviet Union founder Vladimir Lenin during a rehearsal of the Naval parade in St.Petersburg, Russia, Thursday, July 28, 2022. The celebration of Navy Day in Russia is traditionally marked on the last Sunday of July and will be celebrated on July 31 this year. (Photo by Dmitri Lovetsky/AP Photo)

Dr. P.A. Smithe was sent by the American Red Cross as a doctor and surgeon to work at a hospital in Vienna. He sailed to Europe in December 1915 and returned home in August 1916, according to his daughter, who donated his images to the National World War I Museum. Photo: Turkish army, including cavalry, infantry and artillery. (Photo by Dr. P.A. Smithe/National World War I Museum, Kansas City, Mo.)