New York is a city of few boundaries, a city of well-known streets and blocks that ramble on and on, into our literature, dreams, and nightmares. We know the city by the byways that split it, streets like Broadway and Madison and Flatbush and Delancey. From those streets, peering down the blocks and up at the top floors, the city seems immense and endless. And though the land itself may end at the water, the city does not. Long before Broadway was...