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 young Free Syrian Army fighter holds a rifle in Haresta neighbourhood of Damascus January 16, 2013. (Photo by Goran Tomasevic/Reuters)

A woman carries an umbrella as she walks along a street during snowfall in the Iranian capital Tehran, on February 12, 2023. (Photo by Atta Kenare/AFP Photo)

Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

Photographer Lori Nix hand-crafted dioramas are fictional scenes of a post-apocalyptic world in which plants and decay reclaim both grand and mundane structures. Each structure is built in Nix's living room and can take over half a year to build. Photo: Library, 2007. Photographer Lori Nix says this is the most popular image she has made for this project that she calls “The City”. (Photo by Lori Nix)

An African migrant stranded in Costa Rica bathes at a makeshift camp at the border between Costa Rica and Nicaragua, in Penas Blancas, Costa Rica, July 14, 2016. Thousands of African migrants are currently stranded in Costa Rica after they were denied entry into neighbouring Nicaragua, which they have been using as a crossing point in order to reach the United States. According to the Costa Rican Red Cross, most of these people from Africa, Asia and Haiti. It has been reported that many of them paid smugglers to reach Central America. However, when they arrived at the border gates, they were denied entry and were left with nowhere to go. (Photo by Juan Carlos Ulate/Reuters)

Spectators pass through security screening ahead of the New Year's Eve celebration in Times Square in New York, on Sunday, December 31, 2017. (Photo by Peter Morgan/AP Photo)

A mural depicting a resting cat by Russian street artist Vladi is photographed by a man outside a hotel in Hong Kong on November 27, 2023. (Photo by Peter Parks/AFP Photo)