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)

A tourist train is decorated with Christmas lights in Bogotá, Colombia on December 10, 2017. (Photo by Jaime Saldarriaga/Reuters)

A robot named “Robovie-II”, developed by Japanese robotics research institution ATR, moves around at a grocery store during a shopping assisting experiment by utilizing the robot in an ubiquitous network technology platform in Kyoto, western Japan January 6, 2010. (Photo by Yuriko Nakao/Reuters)

Boats moored in the middle of Dal lake are silhouetted against the setting sun on January 15, 2018 in Srinagar, the summer capital of Indian administered Kashmir, India. Kashmir, the Muslim majority state, known as the “Paradise on Earth” has for centuries captured the imagination of many writers, poets and film makers and is integral to the tourist trade. Kashmir has been a contested land between nuclear neighbors India and Pakistan since 1947, the year both the countries attained freedom from the British rule. (Photo by Yawar Nazir/Getty Images)

Sophie Turner (Sansa Stark) and George R. R. Martin attend the “Game Of Thrones” Season 8 NY Premiere on April 3, 2019 in New York City. (Photo by Jeff Kravitz/FilmMagic for HBO)

Fans dressed up in costume await the cast members on the red carpet at the world premiere of the film "The Avengers: Endgame" in Los Angeles, California, April 22, 2019. (Photo by Mario Anzuoni/Reuters)

Attendee Ana Niebla arrives in costume as Princess Penny Wise for opening night of the pop culture festival Comic Con International in San Diego, California, U.S., July 17, 2019. (Photo by Mike Blake/Reuters)

A “caixer” (horse rider) rears up on his horse surrounded by a cheering crowd during the traditional “Jaleo” at the Sant Antoni Festival in Es Castell, Balearic Islands, Spain on July 27, 2019. (Photo by Matthias Oesterle/Zuma Press/Picturedesk.com)