Tourists from Holland peak through a crack in a still-existing portion of the Berlin Wall at the main memorial to the Wall in Bernauer Strasse on the 22nd anniversary of the fall of the Wall on November 9, 2011 in Berlin, Germany. The Berlin Wall, erected by the communist authorities of then East Germany in 1961, divided the city and prevented East Germans from travelling west until the collapse of the Eastern Bloc in 1989. (Photo by Sean Gallup/Getty Images)

A visitor to the New Museum walks through the “Carsten Holler: Experience”, exhibition at the museum on December 14, 2011 in New York City. The show, which has been called an art world amusement park, includes a 102-foot slide that corkscrews down from the fourth floor to the second; an installation of flashing lights that is supposed to make you hallucinate and a sensory-deprivation tank that is meant to resemble the Dead Sea. (Photo by Spencer Platt/Getty Images)

Over 1000 New Year revellers, many in fancy dress, braved freezing conditions in the River Forth in front of the Forth Rail Bridge during the annual Loony Dook Swim on January 1, 2012 in South Queensferry, Scotland. Thousands of people gathered last night to see in the New Year at Hogmanay celebrations in towns and cities across Scotland. (Photo by Jeff J. Mitchell/Getty Images)

A logometer used to determine the Titanic's speed is seen among artifacts recovered from the RMS Titanic wreck site at a press preview of a Titanic artifact auction at the Intrepid Sea, Air & Space Museum on January 5, 2012 in New York City. On April 11, 2012, the 100th anniversary of the maiden voyage of the Titanic, Guernsey's will auction the complete collection of more than 5,000 artifacts recovered from the Titanic wreck site. (Photo by Mario Tama/Getty Images)

Residents observe a police officer take up position during an operation at the Mare slums complex in Rio de Janeiro March 25, 2014. The federal troops have taken control of security operations in Mare slums complex to help quell a surge in violent crime following attacks by drug traffickers on police posts in three slums on the north side of the city, government officials said. (Photo by Ricardo Moraes/Reuters)

An abandoned protection masks in the deserted building near bypass channel for cooling at the Chernobyl nuclear power plant in the Exclusion Zone, Ukraine, April 5, 20177. The Chernobyl nuclear accident occurred on 26 April 1986 in the No.4 light water graphite moderated reactor at the Chernobyl Nuclear Power Plant near Pripyat. An estimated 47,000 people of the city of Pripyat were evacuated after the explosion in 1986. (Photo by Vitaliy Holovin/Corbis via Getty images)

A bull hits a reveller during the first running of the bulls of the San Fermin festival in Pamplona, Spain, July 7, 2018. Each day at 8am hundreds of people race with six bulls, charging along a winding, 848.6-metre (more than half a mile) course through narrow streets to the city's bull ring, where the animals are killed in a bullfight or corrida, during this festival dating back to medieval times and also featuring religious processions, folk dancing, concerts and round-the-clock drinking. (Photo by Vincent West/Reuters)

“Show Time”. It's a normal behavior of mantis. They're doing defence. When they're afraid of; raising their arms and spreading their wings. They looks like smiling dancer. Photo location: Nicosia, Cyprus. (Photo and caption by Hasan Baglar/National Geographic Photo Contest)