MANY other great features on the DOITT maps.
As MACK pointed out, the aerial photos for previous years are centered exactly, so if you choose a particular building address, the older aerial maps would show the exact current boundary of the building. For example a friend lives in Battery Park City, displaying an earlier aerial map would show that the building's "footprint" was at that time in the river.,
Building records on most addresses.
Below the "Show Additional Data...", you can choose all sorts of overlays to the basic street map. Some examples are:
Firehouses
Subway Lines, stations and entrances
FDNY Admin Districts
Precincts
Schools and Hospitals
ZIP code borders
Political districts (Congressional, Council, Census Tract, Election Districts), and much more
Don't know if it's still available, but a few years back you were able to download a helpful 26 page PDF of the DOITT Map User Guide.
