Getting five sets of interviewees to stay put while I ran around a vast, unpredictable metropolis seemed like a stunt that was bound to fail. Yet the idea was irresistible. Such a tour would draw me through the city’s infrastructure, its trains, roadways, and streets, sharpening my understanding of how the great urban machine holds together. I live in New York for its variety, yet I spend my days shuttling between the same few places in Manhattan; here was a chance to really see my hometown, to apprehend its sweep and multiplicity in a compressed way that would amplify both. And let’s face it: New Yorkers like a challenge—especially one that tests them against their city. This promised to be a good one.