There was a time when bells in town squares warned citizens of impending danger. Today, the bells ring again in the form of studies and media reports with warnings about urban problems that plague modern cities and resist solutions. Meanwhile, increasing numbers of people move to cities in pursuit of a higher quality of life. This is the story of cities: Citizens with big expectations versus the endurance of big city problems. It is a still-unfolding story with numerous villains: social inequality, traffic congestion, pollution, crime, unemployment, lack of affordable housing, aging infrastructure, public service shortfalls.