Cities, and especially large urbanized regions, are extremely complex entities. They are not only immense physical constructions - most visible in the scale of the built environment - but also dynamic economic, social, and institutional systems. Each of these systems has its own internal logic, its own geography, and its own trajectory of change over time, but all are interrelated. These relationships, not surprisingly, defy easy generalization. In other words, the challenge of managing growth and change in such systems is daunting.