This paper covers four aspects of cities in which space is of vital importance, either directly or indirectly: wealth creation, involving the links between macroeconomics and cities, and their role in generating innovation and lifting productivity; human and social capital, and in particular the benefits as well as the costs of density and diversity; democratic governance, referring especially to the capacity of municipal government to cope with the challenges of urban development and to promote freedom and the built environment itself, because urban space is an independent variable which can enrich our lives through good design.