Title: Invisible frontier
Description: An adventure guide to New York City's hidden secrets explores a vast urban wilderness that includes subway tunnels, the sewer system, abandoned aqueducts and buildings, the heights of its bridges, and other unusual landmarks.
Subjects: Description and travel, Adventure and adventurers, Roofs, Miscellanea, Antiquities, Outdoor recreation, Tunnels, History, Biography, Historic sites, New york (state), guidebooks
Places: New York, New York (N.Y.), New York (State)
People: David Leibowitz, L. B. Deyo