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)

Konishiki “The Dumptruck” of Hawaii stares down at his opponent during the first Sumo Bashai held outside Japan, at the Albert Hall in London, England. (Photo by Chris Cole /Getty Images). 1991

NASA astronaut Reid Wiseman and European Space Agency astronaut Alexander Gerst (not shown) works outside the space station's Quest airlock in the first of three spacewalks for the Expedition 41 crew aboard the International Space Station in this NASA image released October 8, 2014. (Photo by Reuters/NASA)

A boy and a woman run across a railway track as a train approaches in Chengdu, Sichuan province, China, October 8, 2015. Many residents disregard sign prohibiting this kind of illegal crossing and choose to do so to save time, local media reported. (Photo by Hao Fei/Reuters/Western China Metropolis Daily)

Artists called “Le couple en chocolat” take part in the festival “Statues en Marche” in Marche-en-Famenne, Belgium, July 22, 2018. Living statues are a common sight in many city centres, but it is rare to see such a diverse range of this peculiar form of street art for which performers must keep still for painfully long periods of time to create the desired illusion. (Photo by Yves Herman/Reuters)

Workers demonstrate outside the factory of Hua Yang Printing Holdings Co Ltd on October 30, 2007 in Shenzhen of Guangdong Province, China. Over 1,000 workers of the company have blocked the 107 State Highway where the firm is located, to protest against their employer, who owed half a month's salary to the workers. (Photo by China Photos/Getty Images)

A woman looks out from her stall selling traditional garments and textiles at a market in Ashgabat February 8, 2012. (Photo by Aman Mehinli/Reuters)

The Great Picture” is a black and white panoramic print of Marine Corps Air Station El Toro, an old military outpost. The print measures 111 feet wide by 32 feet high on seamless white muslin cloth. (Photo by Caters News)