The New York Public Library has digitized close to 9,000 pages from 162 historic atlases of the New York City area. The majority of these are fire insurance maps, which are published detailed city maps depicting building structures, lot dimensions, shoreline locations and sometimes, property ownership. This collection of digital images also includes zoning maps, air photos, and detailed topographic surveys.
Available for viewing and downloading on the New York Public Library's website - NYC Fire Insurance, Topographic and Property Maps.