By 2025, China will have built fifteen new 'supercities' each with 25 million inhabitants. It will have created 250 'Eco-cities' as well: clean, green, car-free, people-friendly, high-tech urban centres. From the edge of an impending eco-catastrophe, we are arguably witnessing history's greatest environmental turnaround - an urban experiment that may provide valuable lessons for cities worldwide.

Whether or not we choose to believe the hype - there is little doubt that this is an experiment that needs unpicking, understanding, and learning from. Austin Williams, The...