Part 1 Introduction: Cities for the new millennium. Part 2 Metabolism: How urban ecosystems work: It isn’t waste until you waste it; Energy and emissions to the air; Cities and the hydrological cycle. Part 3 Pathology: What’s gone wrong? Urban land: asset or liability? The air we breathe and the climate we are changing; The water we use and abuse. Part 4 Health: Restoring urban ecosystem health: Restoring urban land to productive use; Clearing the air; Water – our most precious resource. Part 5 Conclusions; International issues; Do we have the means to build the ecological city? Appendices.