Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

A bride looks on as she and others wait to take their wedding vows during a tribal mass marriage ceremony, in which 1101 couples took part, on the outskirts of Mumbai, India, February 17, 2019. (Photo by Francis Mascarenhas/Reuters)

Ferrari driver Fabio Barone and his Ferrari 458 Italia competes against a Roman chariot drawn by two horses on “Ben Hur” movie set at Cinecitta World amusement park on May 11, 2017 in Castel Romano near Rome. (Photo by Andreas Solaro/AFP Photo)

Participants take part in the annual New Year' s Day Parade in central London, United Kingdom on January 1, 2018. Reports state that 8,000 performers representing the London boroughs and countries from across the globe are parading along the streets of London's West End on New Year’s Day. (Photo by Tolga Akmen/AFP Photo)

Performers ride atop a car leading to the the National Circus Day celebration in Santiago, Chile, Saturday, September 4, 2021, amid the new coronavirus pandemic. Chile's Culture Minister set the stage for the first circus performances with a ringside public since the beginning of the pandemic quarantine measures as the South American country looks to fully roll back almost all COVID-19 related restrictions. (Photo by Esteban Felix/AP Photo)

Parts of the Royal Chariot, which will be used during the late King Bhumibol Adulyadej's funeral later this year is seen at the National Museum in Bangkok, Thailand, February 6, 2017. (Photo by Chaiwat Subprasom/Reuters)

Director Taro Kambe directs as he watches acting with VR headset during a rehearsal for ROCKET's 3D virtual reality adult film at the company's studio in Tokyo, Japan, July 31, 2017. Japan is the world's second biggest virtual reality market after the United States and the adult entertainment industry and gaming sector are turning to VR as a new way to distribute content. (Photo by Kim Kyung-Hoon/Reuters)

Chinese-American actress Bai Ling is seen on October 15, 2018 in Los Angeles, CA. (Photo by Hollywood To You/Star Max/GC Images)