Ancient cities as documented by archaeologists and historians have considerable relevance for a broader understanding of modern cities and general processes of urbanization. This article reviews three themes that illustrate such relevance: sprawl, squatter settlements and urban sustainability. Archaeology's potential for illuminating these and other topics, however, remains largely unrealized because we have failed to develop the concepts and methods required to analyse such processes in the past. The following aspects are examined for each of the three themes: the modern situation, the potential insights that archaeology could contribute, and what archaeologists would need to do to produce those insights. The author then discusses some of the benefits that would accrue from increased communication between archaeologists and other scholars of urbanism.