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)

Members of Libyan forces allied with the UN-backed government fire a weapon towards Islamic State militants in neighbourhood Number One in central Sirte, Libya August 28, 2016. (Photo by Ismail Zitouny/Reuters)

A demonstrator confronts a police officer outside the 18th District Police station during a rally after the death of Walter Wallace Jr., a Black man who was shot by police in Philadelphia, Pennsylvania, U.S., October 27, 2020. (Photo by Bastiaan Slabbers/Reuters)

Musicians in Father Frost costumes ride along Nevsky Avenue on the Dedmorobus (portmanteau of “Father Frost” and “bus”) musical bus to entertain citizens ahead of New Year celebrations in St Petersburg, Russia on December 28, 2020. (Photo by Alexander Demianchuk/TASS)

Belgium's Elise Mertens, left, and Aryna Sabalenka of Belarus celebrate with their trophy after defeating Barbora Krejcikova and Katerina Siniakova of the Czech Republic in the women's doubles final at the Australian Open tennis championship in Melbourne, Australia, Friday, February 19, 2021. (Photo by Hamish Blair/AP Photo)

People watch fireworks commemorating the 76th anniversary of the victory in the Great Patriotic War in St. Petersburg, Russia, May 9, 2021. (Photo by Chine Nouvelle/SIPA Press/Rex Features/Shutterstock)

Protesters are detained by police in central Istanbul, Saturday, June 26, 2021. Police used tear gas and rubber bullets to disperse the crowds and detained dozens of LGTBI activists as hundreds defied a ban and tried to stage a gay pride event. (Photo by Emrah Gurel/AP Photo)

A man rides a skateboard at Radical Park in Rio de Janeiro, Brazil, Thursday, June 24, 2021. Hundreds of joggers, dog walkers, skateboarders and picnicking families come each day. (Photo by Bruna Prado/AP Photo)