William B. Helmreich: The New York Nobody Knows

New York City native and sociologist Helmreich proved his dedication to, and satisfied his curiosity about, the city in a wild way: He walked nearly every street in the five boroughs in the course of five years. Tonight he talks about nostalgia, gentrification and ethnic diversity—and how all of these things fit into his new travelogue—with New York Times writer Kirk Semple.