Since the 1990s, new economic geography has received a lot of attention as mainstream economists such as Krugman and others began to focus on where economic activity occurs and why. Coincidentally, international trade, location theory, and urban economics all appear to be asking the same question: where is economic activity located and why? The challenge is to explain the economic concentration or agglomeration of a large number of activities in certain geographical space. This volume breaks down the various types of cities and evaluates the key factors used to look at cities, such as innovation, green growth, spatial concentration, and smart cities in order to understand how cities work. Why is it that certain cities attract talent? How do some cities become business hubs? Why is it that few cities become increasingly competitive while others remain stagnant?