As a kid growing up in Manhattan, William Helmreich played a game with his father they called "Last Stop." They would pick a subway line and ride it to its final destination, and explore the neighborhood there. Decades later, Helmreich teaches university courses about New York, and his love for exploring the city is as strong as ever.Putting his feet to the test, he decided that the only way to truly understand New York was to walk virtually every block of all five boroughs―an astonishing 6,00 .
