Huge Undeground Tunnels Safeguard Greater Tokyo from Floods (photos) www.nippon.com

The Metropolitan Area Outer Underground Discharge Channel was completed 10 years ago and has helped reduced flood damage around the nation’s capital on more than 100 occasions. The world-class underground flood control system not only drains rainwater from low-lying areas but has a pressure adjusting tank that, with its huge columns, has been likened to a giant underground temple.