All urbanized, twenty-first-century settlements will in some way be affected by the shifting pieces of a complicated equation of factors that include resource consumption, environmental performance and unpredictability, economic opportunity, social integration and cultural shift, mass migration, and the balance and ambition of political regimes. These pervasive and perpetual forces have always changed the way we imagine and project urban environments. The combined pressures of global population explosion, measurable and alarming ecological stress and related urbanization, as well as projected food and clean water shortages, force questions about settlement optimization. These strains suggest that those who make policy and design future environments must develop a complex, qualitative understanding of density and how it affects the arrangement of cities. The response pairs measurable data against more culturally driven and fluid aspirations of identity and lifestyle. This symposium discusses the current and near-future status of the fundamental quality of built environments.