In this photo taken Sunday, October 5, 2014, a library official shows a 13th-century German prayer book containing the earliest evidence of the Yiddish language, at Israel's National Library in Jerusalem. This week, Israel's National Library gave The Associated Press a rare peek at a selection of rare historical manuscripts in its collection. (Photo by Sebastian Scheiner/AP Photo)

A picture taken on October 17, 2014 in Vevey shows a giant fork designed by Switzerland's artist Jean-Pierre Zaugg to commemorate Nestle's Alimentarium Food Museum 10th anniversary. World's biggest food company, Swiss Nestle Group announced results sales down by 3.1% for the first nine months of 2014 to 66.2 billion Swiss francs (55.1 billion euros). (Photo by Fabrice Coffrini/AFP Photo)

A young Hindu girl sits for a ceremony where she and other girls are worshipped as “Kumari”, or living goddess, during Ram Navami festival, at a temple in Kolkata, India, Saturday, March 28, 2015. Ram Navami marks the birth of Hindu God Rama. (Photo by Bikas Das/AP Photo)

2014 Underwater Photography Photo Contest winners, Wide angle marine life category, 3rd place. (Photo by Valda Fraser/UnderwaterPhotography.com)

A woman attends a boxing class at Princess Women's Boxing Club in Shanghai December 3, 2014. Women have boxed as long as the sport has existed but for years they were relegated out of national and international competitions in many countries around the world. Female boxers entered the ring in an exhibition match at the 1904 Olympic Games, but it was more than a century later when they were given the green light to make their Olympic debut in London in 2012. (Photo by Carlos Barria/Reuters)

Omsin, a 25 year old femal green sea turtle, rests next to a tray of coins that were removed from her stomach after a surgical operation at the Faculty of Veterinary Science, Chulalongkorn University in Bangkok, Thailand, March 6, 2017. (Photo by Athit Perawongmetha/Reuters)

Two sheep fight in a competition in Zhangjiakou, Hebei province, China on August 1, 2017. (Photo by Reuters/China Stringer Network)

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)