For thousands of years humankind has been living in cities and towns. It has been a long process of evolution, made of change and permanence, and mainly of continuous improvement and adaptation of urban forms to meet human needs and expectations. Then, something happened that began to radically transform our human settlements. New urban landscapes began to emerge, driven by a combination of factors, including demographic growth, the rise of real estate development, new mobility patterns, and innovative planning and architectural theories. These landscapes were, and continue to be, characterized by low levels of density, diversity and sustainability. The book addresses this fundamental problem, arguing for the recovery of structural elements from a six-millennium urban legacy that, in a momentary lapse of reason, were lost in the twentieth century. Central to our view, based on 6000 years of urban culture, is the ground plan concept. The concept was proposed in the mid-twentieth century by geographer M. R. G. Conzen in the field of urban morphology. The book pushes the concept to its limits. It demonstrates how different types of ground plans influence the fundamental three-dimensional characteristics of building fabrics, as well as patterns of socioeconomic diversity and environmental sustainability (emphasizing coexistence rather than causation). These findings are crucial not only for understanding our urban landscapes but also for guiding action to address them.