Mega-city regions are currently a frequent topic of discussion. Researchers are exploring the fundamentals for understanding the role of metropolitan regions and their social, economic, and cultural developments on a national and European basis. The responsible decision makers in politics and business are calling for new measures for greater urban areas. But that is just the start of the problem: Europe seems to lack an awareness for metropolitan regions. For the majority of politicians, planners, institutions, and residents the features of mega-city regions remain invisible. They are scarcely charted; there are no concepts for representing them or any direct sensory understanding of them in everyday life. The book is based on the understanding that the visual depiction of mega-city regions is fundamental to identifying, acting, and developing within existing concentrations of urban populations. Through essays from various disciplines the book approaches the phenomenon and discusses the necessity to visualize mega-city regions.