The shape of future cities: Three speculations

World population has grown dramatically since the Industrial Revolution began 250 years ago. Cities are key elements in this growth, but by 2100, we will all be living in cities of one size or another. Here we speculate what this world will look like. First, the Industrial Revolution represents a clean break from a past composed of hardly any cities to one which is completely dominated by cities. Second, cities will continue to change qualitatively as they get larger but size limits will emerge. Third, cities will no longer be classified by their size but by their internal dynamics.