The world's cities are on pace to balloon from 3.6 billion inhabitants today to more than 6 billion by mid-century. As a result, we face both a dire emergency and a tremendous opportunity. At their best, our modern cities are hubs of human connection, fountains of creativity, and exemplars of green living. Yet at the same time, they still suffer the symptoms of industrial urbanization: pollution, crowding, crime, social fragmentation, and dehumanization. Now is the time to envision what cities can be and to transform them. This book, produced in partnership with the Atlantic Cities, celebrates 12 promising, provocative responses to this challenge, in realms ranging from transportation to food to art. It asks and begins to answer simple-seeming questions: How can we transform cities to be sustainable, efficient, beautiful, and invigorating to the human soul? And practically speaking, how do we get from here to there?