The Reason Why They Are Still Digging Underground in Gwanghwamun, Seoul

At 40 meters underground in Gwanghwamun, Seoul, a tunnel is still being excavated. Once completed, this 2.3km long tunnel will be able to contain 122,000 tons of rainwater. This method was devised because the area beneath Gwanghwamun is already packed with subways, electrical lines, communication cables, and water mains. This approach has already been proven effective. The Sinwol Rainwater Tunnel, completed in 2020, successfully mitigated the record-breaking downpours in 2022. The Gwanghwamun Tunnel is currently under construction with a target completion date of 2030.