The world is rapidly urbanizing, and experts predict that up to 80 percent of the population will live in cities by 2050. To accommodate that growth while ensuring quality of life for all residents, cities are increasingly turning to technology. From apps that make it easier for citizens to pitch in on civic improvement projects to comprehensive plans for smarter streets and neighborhoods, new tools and approaches are taking root across the United States and around the world. In this thoughtful, inquisitive collection, Rob Walker—former New York Times columnist and author of the City Tech column for Land Lines magazine—investigates the new technologies afoot and their implications for planners, policymakers, residents, and the virtual and literal landscapes of the cities we call home.