Tsar Alexander II (1818–1881) known as “The Liberator” lying in state. He was mortally wounded by an assassination attack in St Petersburg. (Photo by Hulton Archive/Getty Images). March 1881

Two guards perform an execution in China, one holding the gun, the other holding a mask over the victim's face. (Photo by General Photographic Agency/Getty Images). Circa 1925

A man irrigating a rice paddy field using a traditional method. (Photo by Fox Photos/Getty Images). Japan, circa 1938

Children feeding the birds in this Victorian Christmas greetings card. (Photo by Hulton Archive/Getty Images). Circa 1885

A bull rams inmates seated at a card table in the Convict Poker event at the Angola Prison Rodeo in Angola, La., Saturday, April 26, 2014. Those competing in the rodeo have to pass a physical to be deemed strong and healthy enough, and thousands of others work year-round making arts and crafts to sell at the event, according to the prison's athletic director. (Photo by Gerald Herbert/AP Photo)

A curious leopard cub toys with a camera at MalaMala Game Reserve in Mpumalanga Province, South Africa. (Photo by Barcroft Media)

“The power of nature”. Magma, ash and gas erupt from Mount Etna in December 2015, rising to a height of several kilometres. Winner: Nature. (Photo by Giuseppe Mario Famiani/SIPA Contest)

Ruins of a building are seen in the old village of Belchite, in northern Spain, November 13, 2016. Almost 80 years ago Tomas Ortin fled under the cover of night from his home in the small town of Belchite on Spain's northern plains to escape with hundreds of others from one of the bloodiest battles of the country's civil war. At 94 years old, Ortin now lives just across the road from Belchite, which has lain in ruins since Republican forces attacked it, a symbol of the destruction caused by the 1936-1939 war in which an estimated 500,000 people died. (Photo by Andrea Comas/Reuters)