400 years ago, Edo was on the verge of ecological collapse. Years of intense logging had led to massive deforestation and the city faced timber shortages, severe erosion, and frequent flooding. But over just a few decades, Edo became one of the most sustainable and efficient cities in history. So, how did this come about? Roman Krznaric explores Edo's transformation into a circular economy. Lesson by Roman Krznaric, directed by Héloïse Dorsan-Rachet.