Satellite photo of Madrid at 4,8km altitude. Credit: Google Earth,. As of 2007 , most humans live in cities. Though this is a relatively recent trend, many of our settlements contain street, block, and building patterns that have developed over centuries. These patterns—which collectively make up what we call "urban form"—are far from a neutral backdrop: they influence who lives where, what businesses find footholds in which locations, and what makes some areas more diverse than others. "Bottom-...