Tokyo Flood Tunnels
The Tokyo Flood Tunnels, an underground engineering marvel that protects the city from flash floods are located beneath Tokyo’s bustling streets. They not only channel rainwater away from urban areas, but also provide escape routes in the event of an emergency.
They are a vital part of the city’s infrastructure, combining functionality with impressive design.
The system, known as the G-Cans Project, is a series of underground tunnels and huge underground chambers built to prevent flooding in the city of Tokyo, which has historically been vulnerable to river overflows during heavy rain and typhoon seasons.
The project is incredible in its scale and complexity, with tunnels up to 6.3km long and gigantic underground chambers capable of containing excess rainwater. These chambers are so large that they can hold up to 200,000 cubic meters of water.
When flooding is expected, these chambers can pump the water away from the city and into the nearby river, thereby reducing the risk of catastrophic flooding in Tokyo.
https://en.wikipedia.org/wiki/Metropolitan_Area_Outer_Underground_Discharge_Channel