Historically, the city and even the city state represented the political identity of great civilizations and the world’s most advanced societies. As a result of rapid urbanization, the “megacity” is making a comeback and is now becoming a trademark of the developing world. This surge of concentrated urban population growth, much of it in Africa and Asia, is taking place in less-developed and sometimes struggling states. Along with rapid urbanization comes a host of opportunities and challenges. Peter Liotta, co- author of The Real Population Bomb: Megacities, Global Security & The Map of the Future, focuses on security issues heightened by rapid urbanization. Jaana Remes discusses the role that cities play in economic growth. Together they provide an overview of the potential risks and rewards inherent in an urbanizing world.