With its 37.7 million inhabitants, Tokyo is the most populated urban zone on the planet. Almost 80% of the Japanese population lives in towns and urban expansion on the archipelago has reached levels unparalleled in Europe. The Japanese capital looks like no other city in the world and is characterised by its wide variety of architectural styles and a constantly evolving urban landscape. Built on a fault line, threatened by flooding and several active volcanoes, the city seems doomed to disappear, and yet… new construction projects abound. Over time, to counter the various threats, and building on the experience gained from past catastrophes, architects have built a “city” beneath the city to tackle the issues relative to earthquakes and flooding.