With a population of almost 38 million people, Tokyo is the most populous urban zone on the planet. Built on a fault line and threatened by floods, the city seems doomed to disappear, yet new construction projects abound. Over time, building on past experience, architects have built a “city” beneath the city to counter threats of flooding and earthquakes. This program explores this experimental laboratory of modern architecture and techincal innovation. Historians, architects, and engineers reveal the amitious projects under development to save this unique city.