A tourist walks inside the Ice Palace glacier hollow at Hintertux glacier, located at around 3250 meters above sea level, in Zillertal, Austria, 02 March, 2016. The hollow's temperature remains constant at 0 degrees Celsius, in summer and winter alike, and is also used by the University of Innsbruck for scientific research projects. (Photo by Lisi Niesner/EPA)

Young Korean women wearing hanbok (Korean traditional dress) walk inside Gyeongbok Palace on March 27, 2016 in Seoul, South Korea. There has been a trend in recent years for the young Koreans to wear the traditional Korean dress, Hanbok. Wearing the traditional dress, they will walk around downtown Seoul on weekends taking selfies, and share their memories with friends on social media, and also to promote their traditional dress to foreign visitors. (Photo by Jean Chung/Getty Images)

The Jade Belt Bridge, also known as the Camel's Back Bridge, is an 18th-century pedestrian Moon bridge located on the grounds of the Summer Palace in Beijing, China. It is famous for its distinctive tall thin single arch.

A young exhibitor arrives with her kitten on a lead at the National Cat Club show at Crystal Palace, London. (Photo by Fox Photos/Getty Images). 2nd December 1931

Rescue workers stand near dead bodies washed ashore in Ton Sai Bay in Thailand's Phi Phi island in this December 28, 2004 file photo. On December 26, 2004, a magnitude 9.15 quake off the coast of Indonesia's Aceh province triggered an Indian Ocean tsunami that killed around 226,000 people in Indonesia, Sri Lanka, India, Thailand and nine other countries. (Photo by Luis Enrique Ascui/Reuters)

A model of a prehistoric icthyosaurus is dragged from its pond in the grounds of Crystal Palace, London, for its annual clean. The 'keeper' is being helped by some of the local police force. (Photo by Fox Photos/Getty Images). February 1927

A Japanese white-eye is seen on a branch of cherry blossoms at Kyoto Imperial Palace on March 26, 2010 in Kyoto, Japan. (Photo by Akihiro I/Getty Images)

Boys in ceremonial uniform at the civil wedding ceremony of American actress Grace Kelly and Rainier III, Prince of Monaco at the Prince's Palace of Monaco, 18th April 1956. Original publication: Picture Post - 8336 - The Hour Of Marriage - pub. 28th April 1956.