Participants attend the annual May bank holiday “Jack In The Green” parade and festival in Hastings, Britain, May 6, 2019. (Photo by Toby Melville/Reuters)

Chrissy Teigen and daughter Luna Stephens seen on the streets of Manhattan on June 24, 2019 in New York City. (Photo by James Devaney/GC Images)

Sara Sampaio is seen wearing a pink knit sweater and a pink leather skirt during Paris Fashion Week Spring/Summer 2019 on September 24, 2018 in Paris, France. (Photo by Timur Emek/Getty Images)

US rapper Saweetie perform on the catwalk at PrettyLittleThing x Saweetie show Runway, Spring Summer 2020, New York Fashion Week, USA on September 8, 2019. (Photo by Splash News and Pictures)

Students, dressed in a whole array of fancy dress outfits, were pictured on a wild night out to kick off Freshers' Week in Leeds, England on September 21, 2019. Freshers' Week is a period before the start of an academic year at a university or tertiary institutions. During this period, students participate in a wide range of social activities. (Photo by N B (PRESS) LTD)

A moto-taxi driver takes two passengers past a burning barricade set up by people protesting fuel shortages in Port-au-Prince, Haiti, Monday, September 16, 2019. Haiti was at a standstill Monday with no public transportation available and closed banks, government offices, and schools amid street protests due to a fuel crisis. (Photo by Dieu Nalio Chery/AP Photo)

“The Supercell”. This shortlisted image by Dennis Oswald Huge farmland of was taken in south-west Oklahoma, US. (Photo by Dennis Oswald/2019 Weather Photographer of the Year/RMetS)

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)