The world has become urban. More than 50% of the human population now resides in areas classified as urban. In developed countries, over 80% of the population now lives in such places. Indeed, in these nations, “megacities” have emerged with populations in excess of 10 million. Cities are the most fundamental form of social organization. They embody most of what people do. They produce most of the world’s wealth. They have the world’s largest accumulation of material wealth. Cities are larger than nations. They contain more people and resources. Their activities are more varied, people’s jobs more diverse, and their impacts more profound. Cities have another valuable attribute: they are resilient systems. This property of resilience has been evident throughout recorded history. Cities have endured innumerable scourges. External events, such as floods, hurricanes, and droughts, have assaulted them. They have suffered internal discord, social conflict, flows and ebbs of wealth and power, and political malfeasance. In every case, people did what they could to heal their afflicted city. They responded constructively. When cities or empires failed, others arose and took their place. And after a while, almost no one remembered the origin of the cities’ worries. They were rebuilt. When citizens joined one another to clothe a place with a collective view of what their city might become, their city and culture both thrived. The resulting places were resilient and sustainable. Such places were made by people who worked to envision a sustainable world and sustainable policies. They have been named cathedrals and civilizations, and they display wealth, humanity, and care. Such places live gracefully, with minimal discord. They eventually pass away or develop into different but also sustainable forms of head and heart.