Alex Honnold, one of the world’s most renowned climbers, has undertaken an extraordinary feat by free soloing Taipei 101—a 1,667-foot skyscraper in Taiwan—without any ropes, harnesses, or safety equipment.

Taipei 101, located in Xinyi District, Taipei, stands at a height of 508.2 meters (1,667 feet) to the tip of its spire and is one of the most iconic skyscrapers globally. The tower, which officially opened on December 31, 2004, was the world’s tallest building from 2004 to 2010 before being surpassed by the Burj Khalifa in Dubai.

The structure features advanced engineering designed to withstand strong typhoons and earthquakes, including a massive tuned mass damper—a 660-metric-ton spherical device suspended between floors 88 and 92 that reduces building movement by up to 40%.

Honnold’s climb, which aired live on Netflix, reportedly earned him a “mid six figures” payout. Honnold stated he would have undertaken the climb even without financial incentive if given permission by the building’s management.