A tunnel with electric switches are seen in Josip Broz Tito's underground secret bunker (ARK) in Konjic, October 16, 2014. In the early 1950s, Josip Broz Tito, the late leader of the former Yugoslavia, ordered the building of the secret bunker, located 900 feet (270 m) underground and near the Bosnian town of Konjic, to safeguard the country's ruling class in case of a nuclear attack. Construction at the complex, which had a cost equivalent price tag of $4.6 billion, continued until 1979, the year before Tito died. (Photo by Dado Ruvic/Reuters)

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)

An animatronic polar bear visits the London Underground on January 23, 2015, to mark the launch of Fortitude, Sky Atlantic&Otilde's new drama starring Stanley Tucci, Michael Gambon and Christopher Ecclestone, which premieres on Thursday 29th January at 9pm. A team of 19 Hollywood prop specialists spent six weeks designing and building the realistic replica animal with six to eight people working on the costume at any one time, using over 60 different materials. (Photo by David Parry/PA Wire)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

Singer Liam Payne’s girlfriend, model Maya Henry, 21, posed in a slashed red gown as she attended an event at The Ritz in the French capital on October 4, 2021. (Photo by Beretta/Sims/Rex Features/Shutterstock)

English television, radio presenter and DJ Maya Jama was alluring as Medusa at Maya Jama's annual Halloween party on October 30, 2021 in London, England. (Photo by mayajama/Instagram)

Trinidadian-born rapper Onika Tanya Maraj-Petty, known professionally as Nicki Minaj went fully nude and straddled a giant teddy bear in new raunchy photos. The rapper shared the revealing pictures while celebrating her 39th birthday on Wednesday, December 8, 2021. (Photo by Instagram)

Indian girls apply colored powder on each other as they wear protective masks as a precautionary measure against coronavirus, during Holi festival celebrations in Bhopal, India, 26 March 2021. Holi marks the beginning of the spring season. Holi will be celebrated as the Hindu spring festival of colors across the country on 29 March. (Photo by Sanjeev Gupta/EPA/EFE)