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 woman wearing a costume takes selfies while waiting for a photo shooting session in front of the Saint Sophia Cathedral in Harbin, Heilongjiang province, China on January 5, 2024. (Photo by Tingshu Wang/Reuters)

Tourists are watching the sunrise from a viewing platform on the Three Gorges Dam in Yichang, China, on June 23, 2024. (Photo by Costfoto/NurPhoto/Rex Features/Shutterstock)

A young girl plays on the glass bottom platform of the Oriental Pear TV Tower as she travels with her family on the second day of the Chinese Lunar New Year holiday, also known as Spring Festival, in Shanghai, China on February 18, 2018. Some 287 million tourists travelled in China during the first four days of the week-long Chinese Lunar New Year holiday, up 11.1 percent from the same period last year, new data showed Sunday. (Photo by Imaginechina/Rex Features/Shutterstock)

A fisherman throws a net for catching fish with his wife in Yanhu fisherman village near Yangzhou, Jiangsu province, China, 18 October 2018. (Photo by Aleksandar Plavevski/EPA/EFE)

People in traditional Chinese costumes attend a parade to celebrate the upcoming Year of the Dragon on January 28, 2024 in Nanjing, Jiangsu Province of China. The Spring Festival, or the Chinese Lunar New Year, falls on February 10 this year. (Photo by Yang Bo/China News Service/VCG via Getty Images)

Zhao Deli waves as he pilots his self-made “flying scooter” in Dongguan, Guangdong Province, China, 12 August 2018 (issued 16 August 2018). Inspired by a cartoon he watched as a child, Zhao Deli sold off his apartment in pursuit of his dream of building a flying scooter. (Photo by Aleksandar Plavevski/EPA/EFE)