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)

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

In this photo taken Thursday January 17, 2013, sled dogs Poncho, left, and his blind brother Gonzo are hooked up for a run at the Muddy Paw Sled Dog Kennel, in Jefferson, N.H. Poncho has taken to helping his blind brother on regular runs. (Photo by Jim Cole/AP Photo)

“Lorenzo Quinn (born May 7, 1966) is an Italian artist and sculptor and the fifth son of the actor Anthony Quinn. By the age of 21 he gained the respect of the New York art community when he was commissioned to make an art work for the United Nations of which a stamp was later made. Quinn was later selected to head the Absolut Vodka ad campaign for which only top international artists are chosen”. – Wikipedia

Photo: Lorenzo Quinn's Vroom Vroom sculpture is installed in its new setting on Park Lane on January 23, 2011 in London, England. The four-metre high sculpture, consists of a vintage Fiat 500, the first car that the sculptor ever bought, grasped by an oversized aluminium child's hand modelled from Quinn's son. The exhibition has previously been displayed in Valencia and Abu Dhabi. (Photo by Matthew Lloyd/Getty Images for Halcyon Gallery)

Festival goers wear Australia day attire at Big Day Out 2012 at the Sydney Showground on January 26, 2012 in Sydney, Australia. (Photo by Mark Metcalfe/Getty Images)

This picture taken on January 26, 2016 shows a monkey sitting on a bench during rehearsal at a monkey training school in a zoo in Dongying, eastern China's Shandong province. Shows featuring performing simians, popular in China and throughout Asia, are expecting a boost in the Lunar New Year of the monkey, which begins on February 8. But they are facing a growing backlash from Chinese people concerned about animal welfare. (Photo by Wang Zhao/AFP Photo)

A Sikh devotee carries on over-sized religious sword during a religious procession to celebrate the birth anniversary of the first Sikh Guru or master, Sri Guru Nanak Dev Ji, the founder of Sikhism in Amritsar, India, 05 November 2014. The birth anniversary of Guru Nanak Dev Ji will be observed on 06 November. (Photo by Raminder Pal Singh/EPA)

Tibetan pilgrims walk outside the Sera Monastery in Lhasa, Tibet Autonomous Region, China, 11 September 2016. Sera Monastery is known as one of the “great three” Gelug university monasteries of Tibet founded in 1419. (Photo by How Hwee Young/EPA)