Cities are mankind's greatest creation. They represent the most eloquent expression of our species' ingenuity, beliefs and ideals. From Babylon and Rome to London, New York and Tokyo, Joel Kotkin examines the evolution of urban life over the millennia in order to establish what made - and makes - a city great. Despite their infinite variety, all cities essentially serve three purposes: spiritual, political and economic. Kotkin follows the progression of the city from the early religious centres of Mesopotamia, the Indus Valley and China, to the imperial centres of the Classical era, through the rise of the Islamic city and the European commercial capitals, ending with today's post-industrial `suburban metropolis'. Today's cities face many problems, and they can only thrive if they remain sacred, safe and busy. This is as true for the developing world, where at least 600 million people now live in `squatter cities' , as it is for the great global cities which face the challenges of shifting demographics, new technologies and the threat of terrorism.