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 model stands in a light backstage after presenting the collection by Russian designer Alena Akhmadullina at The Russian State Library, one of the three national libraries of Russia, the largest library in the country, largest in Europe, in Moscow, Russia, on Wednesday, November 29, 2023. (Photo by Alexander Zemlianichenko/AP Photo)

People wrapped in blankets sit on the road as they are evacuated from a hotel after an earthquake in Kumamoto, southern Japan, in this photo taken by Kyodo April 14, 2016. A powerful earthquake with a magnitude of 6.5 knocked over buildings in southern Japan on Thursday evening, and police said people may be trapped underneath. (Photo by Reuters/Kyodo News)

Dennis Hong a professor of Mechanical & Aerospace Engineering at UCLA Samueli School of Engineering attempts to impede the movement of ARTEMIS, a full-sized humanoid robot with first-of-its-kind technology in Los Angeles, California, U.S., April 13, 2023. (Photo by Mike Blake/Reuters)

A demonstrator is detained by police officers during clashes in downtown Barcelona, Spain, Friday, October 30, 2020. Clashes have erupted in a central Barcelona square between anti-riot police and hundreds who had gathered to protest the mandatory closure of bars, restaurants and other businesses in the latest effort to rein in on coronavirus outbreaks. (Photo by Joan Mateu/AP Photo)

A man waits for Queen Beatrix's abdication ceremony outside the Royal Palace in Amsterdam April 30, 2013. The Netherlands is celebrating Queen's Day on Tuesday, which will also mark the abdication of Queen Beatrix and the investiture of her eldest son Willem-Alexander. (Photo by Paul Vreeker/Reuters)

Two girls dressed up for a night out in Newcastle, United Kingdom on November 01, 2020 – just hours after Boris Johnson's announcement. Johnson says the new measures will begin on Thursday and last until second of December. (Photo by North News and Pictures/The Sun)

A woman sits on the rubble of her house in the aftermath of a deadly earthquake in Kahramanmaras, Turkey on February 14, 2023. (Photo by Nir Elias/Reuters)