A 20 metre high spiral staircase in a tower used as an emergency exit, is seen inside a Federal Reserve bank (Bundesbank) bunker, prior to the bunker's official opening to the public in Cochem, Germany, March 18, 2016. West Germany's Central Bank (Deutsche Bundesbank) stored some 20 billion German marks of emergency notes in two underground bunkers, one in Frankfurt the other in Cochem, between 1964-1988 during the cold war. (Photo by Kai Pfaffenbach/Reuters)

A visitor looks at a sculpture by a Chinese artist Chen Wenling at the "Sculpture by the Sea" exhibition which runs along the Bondi to Tamarama coastal walk in Sydney on October 22, 2015. The world's largest annual free-to-the-public outdoor sculpture exhibition runs from October 22 – November 8 this year and features over 107 sculptures by artists around the world. (Photo by Saeed Khan/AFP Photo)

Winti spiritual leader Ramon Mac-Nack (2nd L) looks on as as his bride Melissa Karwafodi (2nd R) hands a gourd to a Maroon priest (L) as they are wedded in the first Winti marriage ever to be held in public, in district Para, Suriname, November 16, 2015. The Winti religion, which formed centuries ago out of elements of different religious traditions that African slaves brought with them to Suriname, was considered a form idolatry and prohibited by law since the days of slavery until it was finally officially recognized in 1971. (Photo by Ranu Abhelakh/Reuters)

A visitor jumps for a photograph on the world's highest and longest glass-bottomed bridge above a valley in Zhangjiajie in China's Hunan Province on August 21, 2016. The bridge, which opened to the public on a trial basis on Saturday, spans 430 meters (1,410 feet) and rises about 300 meters (984 feet) above a valley in a scenic zone, making it the world's highest and longest glass-bottomed bridge according to Chinese state media. (Photo by Fred Dufour/AFP Photo)

Attendants arrive at an inauguration ceremony of a Hello Kitty amusement park in Anji, Zhejiang province November 28, 2014. With an investment of $325 million, Hello Kitty Park will be China's first large scale amusement park scheduled to open to the public on New Year's day. According to state media, there are nearly 60 theme parks being built across China at the moment. (Photo by Carlos Barria/Reuters)

Many of the 12 million people who entered the US through New York’s Ellis Island wore traditional dress from their homelands. Here: A Ruthenian woman circa 1906 from the region historically inhabiting the kingdom of the Rus, incorporating parts of modern-day Slavic speaking countries. Her outfit consists of a shirt and underskirt made from linen embroidered with traditional floral-based patterns. (Photo by Augustus Francis Sherman/New York Public Library/The Guardian)

One month-old endangered Bornean Orang Utan sleeps on his mother named Miri on Wednesday, March 6, 2013, in Singapore. The Singapore Zoo is renowned for its flagship animal, the Orang Utan, and exhibits both the endangered Bornean and critically endangered Sumatran sub-species in a social setting. It is also known for its efforts in promoting and educating the public about the importance of wildlife conservation through its educational programs and breeding of these endangered species. (Photo by Wong Maye-E/AP Photo)

Elephants enjoy various kinds of fruits and vegetables during an all-you-can-eat elephant buffet held to mark the National Elephant Day at the ancient historical city of Ayutthaya, Thailand, 13 March 2014. The annual National Thai Elephant Day is held on 13 March to celebrate and drawing public attention for more concerted effort to save the species and protect its habitat. Thailand sees a severe decline with less than 3,000 wild elephants left in the kingdom. (Photo by Rungroj Yongrit/EPA)