Urban geographers note that the form of cities has historically always reflected the economic, political, social, and cultural dimensions of their urban inhabitants, and some urban theorists even suggest cities are an 'advanced' form of human habitation. Given that cities are in many ways 'creations' of humans and societies, why do cities have so many economic, social, and environmental challenges, including inequality, crime, pollution, etc.? Despite these challenges, why does the global population continue to urbanize at an unprecedented rate?