Team Strong Silvers member Ngai Hin Kwok, 66, works out as teammate Ng Siu Chi, 57, watches at a stadium in Singapore March 15, 2015. Team Strong Silvers, is a group of senior citizens who train in calisthenics. The trio trains individually at least three times a week, and meets up for joint calisthenics at least twice a month. (Photo by Edgar Su/Reuters)

South Korean workers are seen from a crane as they work on the 123rd floor during the framing completion ceremony of the 'Lotte World Tower' in Seoul, South Kora, 22 December 2015. The building's exterior was completed in a final height of 550 meters, and 123 floors. The ceremony came five years and two months after the construction of the building began and its opening will likely take place at the end of next year when the interior work is set to be completed, the South Korean Yonhap news agency reported. The building is the highest in South Korea and the fifth highest in the world, according to Yonhap. (Photo by Jeon Heon-Kyun/EPA)

A worker works on a “Transformers” replica on the outskirts of Shanghai, June 18, 2014. Li Lei, owner of a small factory, uses his spare time and money to build “Transformers” replicas for rent or sale. The new Transformers movie, which is premiering later this month, has brought the factory many new orders, according to Li. (Photo by Aly Song/Reuters)

The Macy's inflation team works on giant balloons as they prepare ahead of the 96th Macy's Thanksgiving Day Parade in New York City, United States on November 23, 2022. (Photo by Lokman Vural Elibol/Anadolu Agency via Getty Images)

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)

Groundsman Darren Cordingley on his way out of the maze on July 11, 2024. Gardeners have had their work cut out after spending a whopping 520 hours trimming one of the world's biggest hedge mazes. It has taken a team of 13 working eight hours a day for five days to tackle the enormous maze at the Longleat estate in Wiltshire, UK. (Photo by Max Willcock/Bournemouth News)

An aerial view of Lake Salt as teams conduct salt extraction works at lake which is a significant portion of Turkiye's salt need is met in Ankara, Turkiye on August 11, 2022. Salt extraction works lasts for about 3 months and continues with the recession of the waters in Lake Salt. The salt extracted from the lake, where salt is produced with a purity of 99 percent, is sent to more than 60 countries. (Photo by Emin Sansar/Anadolu Agency via Getty Images)

A Palestinian youth jumps with a sword as he demonstrates his ninja-style skills for the photographer in front of the ruins of buildings, that were destroyed in 2014 war, in the northern Gaza Strip January 29, 2016. The youths, who have been receiving martial arts training at local clubs in Gaza for the past two years, decided to form a team to hold regular shows in the hope that the publicity generated will eventually lead to them being invited to participate in international contests. (Photo by Mohammed Salem/Reuters)