General view of the monument to memory of soldiers who liberated the city of Knin – in Knin, Croatia on November 10, 2014. Across the former Yugoslavia stand giant monuments to a state that no longer exists, once visited and celebrated during public holidays such as Republic Day on November 29, marking the creation of socialist Yugoslavia. Many are now neglected or ignored, aging symbols of a joint state forged during World War Two but torn apart by nationalism half a century later. Republic Day is no longer marked in any of the seven independent states that emerged from its ashes. (Photo by Antonio Bronic/Reuters)

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)

In this aerial view the officers' building and an auditorium stand at the former Soviet military base on January 26, 2017 in Wuensdorf, Germany. Wuensdorf, once called “The Forbidden City”, was the biggest base for the Soviet armed forces in communist East Germany from 1945 until the last Soviet troops left in the early 1990s following the end of the Cold War and the reunification of Germany. (Photo by Sean Gallup/Getty Images)

Aerobatic aircrafts fly during a performance at the Airshow Zhengzhou 2017 in Zhengzhou, capital of central China's Henan Province on April 27, 2017. The 5-day air show kicked off in Zhengzhou on Thursday, aiming to build a general aviation gathering center for business and communications. (Photo by Li An/Xinhua via ZUMA Wire)

A weather vane on a farm building close to the HS2 line on November 24, 2020 in Great Missenden, England. HS2 protesters continue to occupy key infrastructure sites along the proposed HS2 route claiming that the project is “the most carbon-intensive and environmentally destructive project in UK history”. (Photo by Jim Dyson/Getty Images)

A raccoon scratches herself on the window sill of the Paige Donnelly Law Firm on the 23rd floor of the UBS Plaza building in St. Paul, Minnesota, U.S., June 12, 2018, in this image obtained from social media. (Photo by Evan Frost/MPR News via Reuters)

A photo taken on August 21, 2017 shows girls passing in front of a building with a display of the Soviet state founder Vladimir Lenin Order in Volgograd, Russia. Volgograd Arena will host several cames of the FIFA World Cup 2018. (Photo by Mladen Antonov/AFP Photo)

Zhao Deli waves as he pilots his self-made “flying scooter” in Dongguan, Guangdong Province, China, 12 August 2018 (issued 16 August 2018). Inspired by a cartoon he watched as a child, Zhao Deli sold off his apartment in pursuit of his dream of building a flying scooter. (Photo by Aleksandar Plavevski/EPA/EFE)