What makes cities successful? It's a question we ask every week here on Smart City. And this week we have two authorities from the University of Chicago to address that topic - one with a very local view and the other with a global outlook.

Sean Safford has studied the decline of Rust Belt cities and found that particular kinds of social networks were key to a city's ability to renew.

Saskia Sassen has studied global cities and concluded that corporate headquarters are less important to a city than are globe-trotting consultants.

We'll talk to Sean Safford and Saskia Sassen on the next Smart City.

Please note: This is a rerun of a show from March 11, 2006.