The great transition from farm to city is filled with economic, social, and political promise. Cities are the product of a triad of forces. This economic premise explores how the three forces of spatial transformation-physical infrastructure, human interactions, and public policy- come together and shape cities. But too many cities in Sub-Saharan Africa continue to suffer from the oldest urban scourge- unclean water. Crime and murder turn many Latin American neighborhoods into places of terror rather than opportunity. Limited transport options can turn daily commutes in Asia's mega cities into arduous treks. Shantytowns are a regular sight in many of the world's burgeoning cities. So policy makers and city mayors need to tackle a wide range of problems, from debilitating conditions in urban slums to the lack of basic services such as clean water and sanitation, inadequate housing, the exclusion of the poor from the city's socioeconomic fabric, and the management of natural hazards and pollution. If these challenges are left unaddressed, cities can become a source of social and political instability. With the right policies, cities can become engines of transformative change toward inclusive, people-centered, and sustainable development. Urbanization now has the potential of transforming the developing world, and that's why getting urban policies right is important. There is no future in rural poverty- the path to prosperity inevitably runs through cities. The right approach is not to accept the urban failures that often exist now, but to rethink cities and try to imagine how to get to a brighter urban future.