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)

Majesty Davis, 3, cries while visiting Santa Claus, who sits behind a plexiglass divider due to the coronavirus disease (COVID-19) pandemic, at the Willow Grove Park Mall in Willow Grove, Pennsylvania, U.S. November 14, 2020. (Photo by Mark Makela/Reuters)

The Soyuz MS-17 spacecraft carrying the crew formed of Kathleen Rubins of NASA, Sergey Ryzhikov and Sergey Kud-Sverchkov of the Russian space agency Roscosmos blasts off to the International Space Station (ISS) from the launchpad at the Baikonur Cosmodrome, Kazakhstan on October 14, 2020. (Photo by Russian space agency Roscosmos/Handout via Reuters)

Japanese women wearing kimonos take a selfie as they attend their Coming of Age Day celebration ceremony at Toshimaen amusement park in Tokyo, Japan on January 14, 2019. Coming of Age Day is a Japanese holiday held every January to celebrate people who have reached 20 – the official age of adulthood in Japan. (Photo by Issei Kato/Reuters)

A skier in a festive costume attempts to cross a pool of water at the foot of a ski slope while competing in the annual Gornoluzhnik amateur event to mark the end of the ski season at the Bobrovy Log ski resort in the suburbs of the Siberian city of Krasnoyarsk, Russia, April 14, 2019. (Photo by Ilya Naymushin/Reuters)

An Iraq fan poses before the World Cup 2022 Qualifier 2nd round Group C football match between Iraq and Iran at Amman International Stadium in Amman, Jordan on November 14, 2019. (Photo by Muhammad Hamed/Reuters)

Three young women in their 20s brawling on a busy street on the route from the track to the town centre during day four of the William Hill St Leger Festival at Doncaster Racecourse, England on September 14, 2019. (Photo by Nb press ltd)

A cat sleeps between customers inside “Meow” cafe, where diners can play, interact or adopt cats given away by their former owners or rescued from the streets, in Monterrey, Mexico, May 14, 2016. (Photo by Daniel Becerril/Reuters)