We don't typically see an upside to slums—the squalid, makeshift settlements that house one-third of the urban population in developing countries. But not everyone's so glum. The economist Edward Glaeser, for instance, has argued that slums don't make people poor, but rather attract and inspire poor people seeking a better life in the city.
Shirish Sankhe, a director in McKinsey's Mumbai office, offers more cause for optimism. For him, slums are cities waiting to be built.