This book examines urban growth and the dynamics that are transforming the city and city regions in the 21st century focusing specifically on the spatial aspects of this process in the “Urban Century”. Forces that are driving city growth include agglomeration spillovers, concentration of innovation and entrepreneurship, diversity of information and knowledge resources, and better amenities and higher wages. These benefits produce a positive reinforcing system that attracts more people with new ideas and information, fuelling innovation, new products and services and more high-wage jobs, thereby attracting more people. Such growth also produces undesirable effects such as air and water pollution, poverty, congestion and crowding. These combined factors both impact and change the geography and spatial dynamics of the city. These transformations and the public policies that may be critical to the quality of life, both today and in the future, are the substance of this book.