An Afghan vendor selling birds to be kept as pets wait for customers in his shop in Kabul on December 11, 2021. (Photo by Ahmad Sahel Arman/AFP Photo)

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)

U.S. Marines kick in a door while securing a building next to the main hospital in central Baghdad April 15, 2003, which will be used as a temporary Iraqi police headquarters. (Photo by Jerry Lampen/Reuters)

Beach Policeman, Potomac River, 1922. (Photo by National Photo Company/Colorized by Patty Allison)

Two ruddy shelducks fly under a double rainbow in Odisha, India in July 2022. These birds are ruddy shelduck, known locally as the Brahminy duck. They have a wingspan of between 43 and 53 inches and stand at a maximum of 28 inches tall. (Photo by Suman Das/Media Drum Images)

A salsa dancer performs in the “Salsodromo” parade, which marks the start of the Fair of Cali, Colombia, December 25, 2015. Picture taken December 25, 2015. (Photo by Jaime Saldarriaga/Reuters)

A curious leopard cub toys with a camera at MalaMala Game Reserve in Mpumalanga Province, South Africa. (Photo by Barcroft Media)

Completion is near on Monaco's tallest skyscraper ever, and its first new one since the 1980s. Fueled by a luxury-housing boom in the tax-haven nation, the Odeon Tower's so-called Sky Penthouse is expected to sell for more than any other apartment in the world has ever sold before. Photo: The five-story Sky Penthouse is expected to be complete in September 2015. The water slide extends from a dance floor in the residence down to a private infinity pool. (Photo by Tour Odeon)