Book excerpt: Did alligators ever really live in New York's sewers? What's it like to explore the old aqueducts beneath the city? How many levels are beneath Grand Central Station? And how exactly did the pneumatic tube system that New York's post offices used to employ work? In this richly illustrated historical tour of New York's vast underground systems, Julia Solis answers all these questions and much, much more. New York Underground takes readers through ingenious criminal escape routes, abandoned subway stations, and dark crypts beneath lower Manhattan to expose the city's basic anatomy. While the city is justly famous for what lies above ground, its underground passages are equally legendary and tell us just as much about how the city works.