From the host of NPR's Morning Edition, a deeply reported portrait of Karachi, Pakistan, a city that illuminates the perils and possibilities of rapidly growing metropolises all around the world. In recent decades, the world has seen an unprecedented shift of people from the countryside into cities. As Steve Inskeep so aptly puts it, we are now living in the age of the "instant city," when new megacities can emerge practically overnight, creating a host of unique pressures surrounding land use, energy, housing, and the environment.