The giant metal structure sits 330ft above the ground on the roof of a 22 storey office block in Dutch capital Amsterdam on September 6, 2016. Tourists sit in a playground-style chair as they propel themselves them over the edge of the building with only thin-air between them and the ground below. Engineers spent several years designing and building the breathtaking swing. By being fixed to the top of a building it reaches new heights – dwarfing other swings around Europe but trailing behind the 1,150ft high mechanical rides at the Stratosphere Hotel in Las Vegas, Nevada. (Photo by Huub Zeeman/SWNS.com)

A woman directs traffic in the pouring rain in Pyongyang, North Korea on May 3, 2016. The city is preparing for the Workers' Party Congress starting on May 6th. It will be the first time since 1980 that the ruling party has convened. (Photo by Linda Davidson/The Washington Post)

Izzy Paskowitz helps Nixee Grace Chanowsky, 4, catch a wave Monday, August 18, 2014 at Wrightsville Beach, N.C. during the Annual Surfers Healing event for children with autism. Hundreds of people made their way to the beach to watch and cheer on the camp that was founded by Israel and Danielle Paskowitz. (Photo by Mike Spencer/AP Photo/The Star-News)

Two Bulgarian tourists pose in front of the Eiffel Tower in Paris on their last day in the capital on March 24, 2014. (Photo by Franck Fife/AFP Photo)

In this timed-exposure night photo taken early on February 12, 2017, Mount Sinabung volcano spews reddish smoke and ash, as seen from the Karo district in North Sumatra province. Activity levels have increased in the past week, with Sinabung shooting hot ash clouds into the sky dozens of times, according to the local volcano monitoring agency. (Photo by AFP Photo/Stringer)

Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)

A Hindu worshipper throws vegetables into the crater as offerings during the Kasada Festival at Mount Bromo in Probolinggo, Indonesia's East Java province, August 1, 2015. Every year people gather for the annual festival where offerings of rice, fruit, vegetables, livestock or money are made to Hindu gods at the active volcano to ask for blessings and assure a bountiful harvest. (Photo by Reuters/Beawiharta)

AP photographer Anja Niedringhaus laughs as she attends a swimming event at the 2004 Olympic Games in Athens, August 21, 2004. Niedringhaus, a veteran Associated Press photographer who had covered wars around the world was shot dead and another reporter was wounded on April 4, 2014 when an Afghan policeman opened fire on them in eastern Afghanistan, the news agency said. (Photo by Reuters/Staff)