There will be 8.3 billion human beings on Earth by 2030, and the more the better. We have the opportunity to create a world of expansive megacities - including one around old London. Doing so will advance the art, science and processes of manufacturing. But to deploy those abilities we must shrug off the dogma of sustainability that insists only small can be beautiful. Humanity has come a long way since the first modular mega-structure was built at Ur, on land that is now Iraq. There, four mil