A woman looks out of a dusty window after boarding a bus to be transported to see the casket of Nelson Mandela at the Union Buildings in Pretoria, South Africa, Wednesday December 11, 2013. On Thursday, December 5, 2013, Mandela died at the age of 95. (Photo by Markus Schreiber/AP Photo)

The love padlocks, called cadenas d’amour, multiplied until there were thousands of love tokens on the bridge, each engraved with a message of love. (Photo by Charles Platiau/Reuters)

Young Ian Archibald ponders the consequences of a complex critical study of beauty contestants during the Miss TV Times finals in London. (Photo by Central Press/Getty Images). 30 July 1971

Public Space series, 2015. This series by Morteza Niknahad and Behnam Zakeri tends toward cinema, taking an almost cartoonish view of modern life in Iran. This work was inspired by the social life of dolphins. (Photo by Morteza Niknahad and Behnam Zakeri/The Guardian)

Swiss police officers stand beside of mock gates of the NEAT Gotthard Base Tunnel inside the event hall for the upcoming opening ceremony near the town of Erstfeld, Switzerland May 31, 2016. The celebrations of the opening of the Gotthard Base Tunnel will start on June 1, 2016. With a length of 57 km (35 miles) crossing the Alps, the Gotthard Base tunnel is the world's longest train tunnel. (Photo by Arnd Wiegmann/Reuters)

A man covered with mineral-rich mud smiles on a bank of lake Tus in Khakassia region, southwest of the Siberian city of Krasnoyarsk, Russia, July 16, 2016. (Photo by Ilya Naymushin/Reuters)

In this picture taken on November 28, 2016, a hot-air balloon carrying tourists sails over the archeological site at sunrise in Bagan. Located in central Myanmar, Bagan is home to more than 2,000 ancient Buddhist monuments deeply revered in the Buddhist-majority nation and is one of the country's most popular tourist destinations. (Photo by Dale De La Rey/AFP Photo)

Inmates stand next to food during a Christmas event at Sarita Colonia male prison in Callao, Peru, December 18, 2015. For the event, inmates prepared Christmas meals for a culinary competition and took part in dances and songs. (Photo by Mariana Bazo/Reuters)