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 photo from Madonna’s high school yearbook at her childhood home in Rochester, Michigan, circa 1973. (Photo by Rebel Images/Rex Features/Shutterstock)

Wrestlers perform during an all-female wrestling event on International Women's Day at the Resistance Gallery in Bethnal Green on March 8, 2019 in London, England. (Photo by Jack Taylor/Getty Images)

Students participate in a wet t-shirt contest at the MTV Beach Bash party put on by Global Groove at the Bahia Mar Hotel during the annual ritual of Spring Break March 26, 2008 on South Padre Island, Texas. The South Texas island is one of the top Spring Break destinations and attracts students from all over the country. (Photo by Rick Gershon/Getty Images)

British television actress Tracy Shaw poses during a photoshoot held in 2000, in England. (Photo by Stephen Perry/Getty Images)

“Hellfest is an annual music festival which takes place in Clisson, France in mid-June. It is held within the Val de Moine sport complex in Clisson, approximately 35 km south-east of the city of Nantes, and approximately 400 km south-west of the nation's capital Paris. Billed as an “extreme music festival”, the programme features a variety of heavy metal, hard rock, punk and hardcore acts”. – Wikipedia. Photo: HellFest 2013. (Photo by Cesar Hernandez)

A tear rolls down the cheek of Karima el-Mahroug, also known as Ruby, a Moroccan woman at the center of ex-Premier Silvio Berlusconi's s*x-for-hire trial, as she reads a statement to reporters during a protest outside the court house, in Milan, Italy, Thursday, April 4, 2013. The Moroccan woman at the center of ex-Premier Silvio Berlusconi's s*x-for-hire trial has denounced what she says is psychological warfare being waged against her by Italian prosecutors. Ruby, read out a lengthy statement Thursday to a gaggle of reporters in front of Milan's courthouse denying she was a prostitute and insisting that prosecutors hear her side of the story. (Photo by Luca Bruno/AP Photo)