High above the bustling thoroughfares of central Seoul, the gap between two prominent high-rises will transform into an extraordinary arena this fall. On Thursday, Estonian aerial athlete Jaan Roose will step onto a narrow polyester ribbon stretched 120 meters above Gwanghwamun, crossing a 160-meter highline suspended between the Koreana Hotel and the Dong-A Media Center in Korea’s first urban high-altitude slackline performance. Unlike tightrope walking, slacklining relies on a flat, dynamic webbing that bounces and sways under tension, allowing athletes to execute acrobatic flips and spins midair. The event, sponsored by the Seoul Metropolitan Government and organized by Red Bull Korea, will feature Roose performing world-class tricks in two sessions scheduled for 1:00 p.m. and 4:00 p.m. For Roose, a three-time world champion known for completing a historic 3.6-kilometer crossing over Italy’s Strait of Messina in 2024, the Seoul performance is deeply personal. After experiencing "jultagi" — Korea’s traditional tightrope performance, which is registered on UNESCO’s Intangible