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)

Gold medalists Kikkan Randall and Jessica Diggins of the United States dancing during the medal ceremony for Cross-Country Skiing – Ladies' Team Sprint Free on day 13 of the PyeongChang 2018 Winter Olympic Games at Medal Plaza on February 22, 2018 in Pyeongchang-gun, South Korea. (Photo by Eric Gaillard/Reuters)

2016 Rio Olympics, Rhythmic Gymnastics, Preliminary, Group All-Around Qualification, Rotation 1, Rio Olympic Arena, Rio de Janeiro, Brazil on August 20, 2016. Team Brazil (BRA) compete using clubs and hoops. (Photo by Mike Blake/Reuters)

In this photo provided by Mickey Nuttall, members of an international team of skydivers join hands, flying head-down to build their world record skydiving formation, Friday, July 31, 2015, over Ottawa, Ill. (Photo by Jason Peters via AP Photo)

England fan stripped down to her underwear and jumped in the canal in Birmingham, United Kingdom after team lose the 2018 World Cup semi- final against Croatia in Moscow on July 11, 2018. (Photo by Caters News Agency)

Leicester City hostesses take pictures in front of a billboard as people gather to watch the team's English Premier League soccer match against Everton on a big screen, in Bangkok, Thailand, May 7, 2016. (Photo by Jorge Silva/Reuters)

Natalie Geisenberger of Germany, Johannes Ludwig of Germany, Tobias Wendl of Germany and Tobias Arlt of Germany celebrate their teammates slide winning gold during the Luge Team Relay on day six of the Beijing 2022 Winter Olympics at National Sliding Centre on February 10, 2022 in Yanqing, China. (Photo by Thomas Peter/Reuters)

Lea Meyer of Team Germany falls into the water obstacle during the Women’s 3000m Steeplechase heats on day two of the World Athletics Championships Oregon22 at Hayward Field on July 16, 2022 in Eugene, Oregon. (Photo by Martin Rickett/PA Wire Press Association)