A young child reaches out to a Gentoo penguin as it swims in its enclosure at Pairi Daiza Park in Cambron-Casteau, Belgium, Monday, July 5, 2021. Pairi Daiza, one of the biggest zoos in Europe, has recently added ten Gentoo penguins to their animal population. (Photo by Virginia Mayo/AP Photo)

Off from school due to the Thanksgiving holiday this week, Felix Naranch, 7, right, and his brother Asa Naranch, 3, play with their father Stu Naranch in a pile of fall leaves that they raked together in a park, Tuesday, November 23, 2021, in Washington. (Photo by Jacquelyn Martin/AP Photo)

A billboard depicting a soldier, with a slogan reading “Contract service. A real man's job”, in St. Petersburg, Russia, 02 June 2023. On 24 February 2022, Russian troops entered Ukrainian territory in what the Russian president declared a “Special Military Operation”, starting an armed conflict. (Photo by Anatoly Maltsev/EPA)

General view during First Round Group A basketball game Ivory Coast v China in the FIBA Basketball World Cup at the Wukesong Arena in Beijing, China on August 31, 2019. (Photo by Thomas Peter/Reuters)

A Capetonian watches the sun rise from the top of Signal Hill as smoke engulfs the city of Cape Town, South Africa, Tuesday April 20, 2021. A massive fire spreading on the slopes of the city's famed Table Mountain, at right, is kept under control as firemen and helicopters take advantage of the low winds to contain the blaze. (Photo by Jerome Delay/AP Photo)

Veterinarians and biologists from the Quito Zoo and the Andean Condor Foundation fit a tracking collar that juvenile Andean bear Tupak will wear for the next four years, prior to his reintroduction into the wild, after the bear's life was deemed in danger due to proximity to humans, in Quito, Ecuador on March 31, 2024. (Photo by Karen Toro/Reuters)

A yawning leopard appears to be laughing instead at Chobe National Park in Botswana in January 2023. (Photo by Nick Dale/Solent News & Photo Agency)

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)