"By the way, did I mention it also travels in time?"

Travel The New Yorker meets William Helmreich, a sixty-seven-year-old professor of sociology at CUNY, who has walked every street in New York:

"Helmreich is extraordinarily energetic and voluble. “The New York Nobody Knows” is his fourteenth book (he’s also written about ethnic stereotypes, Holocaust survivors, and black militants). “I love the city,” he said as we began walking. “I love to read about the city, to live the city, to walk the city.” During his four years of research, he walked almost every day. “I did it in the morning. I did it in the evening. I did it on the weekends. I did it in the rain, in the snow, in the summer. It came to about thirty-five, forty miles a week, a hundred twenty a month, fifteen hundred a year.”