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

Participants wearing medieval costumes re-enact the 1620 battle of Bila Hora between Bohemian Estates and Austrian Imperial with Catholic forces in Prague, Czech Republic September 18, 2016. (Photo by David W. Cerny/Reuters)

“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)

Carnival revellers carry burning wooden sticks during the traditional Swiss Chienbaese celebration in Liestal near Basel February 22, 2015. (Photo by Ruben Sprich/Reuters)

Classic antique cars are seen at an auto dealer in West Branch, Iowa, March 6, 2015. Iowa, the American heartland. Endless farm fields and quiet towns. 56,273 square miles that are soon to become the focus of the nation as the long process of electing the next U.S. president begins. (Photo by Jim Young/Reuters)

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

A boy tumbles as he plays soccer on the streets of the Khayelitsha township in Cape Town, December 3, 2009. (Photo by Kai Pfaffenbach/Reuters)