Cities are amongst our greatest creations. Yet at the start of the twenty-first century there is increasing concern over their unchecked expansion and the detrimental effect this is having on the planet, as induced climate change and ever increasing demands upon the world's resources take effect. How can we make the world's cities more sustainable? Ian Douglas tells the story of cities - why they exist, how they have evolved, the problems they have encountered and those they will face as our century progresses. Global in geographical coverage, and ranging from the cities of the classical world to the megacities of today, it is the first comprehensive environmental history of cities.