A quote, and a reference, that requires no explanation:
If you wish to understand the future you need to understand the city, for the human future is an overwhelmingly urban future. The city may have always been synonymous with civilization, but the rise of urban humanity has been something that has almost all occurred after the onset of the industrial revolution. In 1800 a mere 3 percent of humanity lived in cities of over one million people. By 2050, 75 percent of humanity will be urbanized. India alone might have 6 cities with a population of over 10 million.
The trend towards megacities is one into which humanity as we speak is accelerating in a process we do not fully understand let alone control.