Revellers take part in the annual Gay Pride parade along Paulista Avenue in Sao Paulo, Brazil, May 29, 2016. (Photo by Nacho Doce/Reuters)

A child falls sleep while people take part in the 35th India Day Parade in New York August 16, 2015. (Photo by Eduardo Munoz/Reuters)

The International Trophy float on the parade route during the 123rd Rose Parade presented by Honda on January 2, 2012 in Pasadena, California. (Photo by Frederick M. Brown/Getty Images)

The Elf on the Shelf balloon floats down Sixth Avenue during the 88th Annual Macy's Thanksgiving Day Parade in New York November 27, 2014. (Photo by Andrew Kelly/Reuters)

The "Skylanders Eruptor" balloon moves by people on balconies during the 89th Macy's Thanksgiving Day Parade in the Manhattan borough of New York, November 26, 2015. (Photo by Andrew Kelly/Reuters)

Women dance in costume during the West Indian Day Parade in Brooklyn, New York September 7, 2015. The parade, which takes place annually, celebrates Caribbean culture and history. (Photo by Andrew Kelly/Reuters)

Parent hedgehogs Maria, left, and Gosha, 2nd right, eat with their albino babies in a private Zoo in Moscow, Russia, Thursday, August 22, 2013. Three rare albino hedgehog babies, born on the same day as Britain's new prince, have moved into a miniature castle at a Moscow petting zoo. The three are named after the Prince of Cambridge – George, Alexander and Louis. On Thursday, when they turned one month old, they were shown their new home at the All-Russia Exhibition Center. (Photo by Alexander Zemlianichenko Jr./AP Photo)

To an outsider, their passion is at times illegal and often on the verge of life and death. But climbing rooftops of high-rise buildings and exploring abandoned facilities is in the blood of these young Muscovites. The small group calls itself “Rudex”, which stands for “roof and decay exploration”, and is akin a Western youth craze known as urbex or “urban exploration” of man-made structures. Here: Urban explorer Vad Him of Rudex team jumps whilst on a rooftop in Moscow, Russia, August 14, 2017. (Photo by Maxim Shemetov/Reuters)