Željava Air Base, situated on the border between Croatia and Bosnia and Herzegovina under Plješevica Mountain, near the city of Bihać, Bosnia, was the largest underground airport and military air base in the former Yugoslavia, and one of the largest in Europe. (Photo by Thomas Windisch/Exclusivepix Media)

A displaced Iraqi girl, who fled her home, cries during a battle between Iraqi forces and Islamic State militants, near Badush, Iraq, March 16, 2017. (Photo by Reuters/Stringer)

Demi Rose attends Sixty6 Magazine – issue two launch party at Paper club on March 22, 2017 in London, England. (Photo by Splash News and Pictures)

Sport category, winner: Yuan Peng. Liu Bingqing and Liu Yujie are twin sisters who have studied and trained in gymnastics since their early childhood in Jining, China. (Photo by Yuan Peng/Sony World Photography Awards)

A person dressed as Republican presidential nominee Donald Trump participates in the Greenwich Village Halloween Parade in Manhattan, New York, U.S., October 31, 2016. (Photo by Andrew Kelly/Reuters)

A participants mends his vintage car during the annual London to Brighton veteran car run in London, Britain November 6, 2016. Around 600 classic cars took part in the annual 60 mile journey to the south coast resort. (Photo by Neil Hall/Reuters)

People take pictures of 30 Rockefeller Plaza as it is lit in the colors of the Democratic and Republican parties ahead of the U.S presidential election in Manhattan, New York, U.S., November 7, 2016. (Photo by Andrew Kelly/Reuters)

Men pull with a rope the body of an Islamic State fighter before burying him near Karamah, south of Mosul, Iraq November 11, 2016. (Photo by Goran Tomasevic/Reuters)