An urban fox walks alongside the Mall in central London, Britain, November 29, 2016. (Photo by Toby Melville/Reuters)

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 hot air balloon in tortoise shape flies in the air during the Tazaungdaing air balloon festival in Pyin Oo Lwin, Myanmar, 25 November 2015. During the festival, hot air balloons made of multicolored papers and hung with paper lanterns, fireworks and fire sticks are exploded in mid-air. (Photo by Hein Htet/EPA)

Ivorian police officers of the Anti-Riot Brigade (BAE) contain the crowd during a performance by French rapper Okou Armand Gnakouri known as Kaaris during the Festival of Urban Music of Anoumabo (Femua) in Abidjan on April 28, 2019. The performance of French-Ivorian rapper Kaaris at the Festival of Urban Music of Anoumabo (Femua) in Abidjan escalated into violence after a crowd surge, causing some minor injuries, according to an AFP journalist at the concert. (Photo by Sia Kambou/AFP Photo)

A woman jumps on a giant fried egg art installation as part of “Hecho en Casa” (Made at home) urban artwork festival in downtown Santiago, Chile, November 8, 2016. (Photo by Pablo Sanhueza/Reuters)

People look at a downhill rider during the Urban Bike Inder Medellin race final at the Comuna 1 shantytown in Medellin, Antioquia department, Colombia on November 19, 2017. (Photo by Joaquin Sarmiento/AFP Photo)