Fraunces Tavern[1], the oldest surviving building in Manhattan, built in 1671 should have been glowing red in the Financial District. In this visualization it is shaded blue for 1900. It was the first building I checked and it was spectacularly wrong; this does not bode well.
This is a very common issue in NYC, my building is also listed as built in 1900. Someone with real estate knowledge told me a fire destroyed many building records (not sure when), so the city defaulted those records to 1900.
edit: I just read this somewhere: "But a word of caution. Buildings built before 1900 are often labeled 1899 or 1900 in city databases." So there may be two separate issues at play here.
Does the nyc opendata initiative have any crowd sourced programs to repair broken records? Could be a win/win for developers and the city if they would accept feedback on their datasets.
Unfortunately gov has for the most part been reluctant to adopt such practices so far. However NPS Maps have been using crowdsourced data from OpenStreetMap and park visitors in their map products.
That building was actually built in 1719. Which is probably why they picked arbitrary dates vs using 3rd party input. If they see 1900 then the construction date is old and probably unknown which is good enough.
DeLancey built the current building as a house in 1719. The small yellow bricks used in its construction were imported from the Dutch Republic and the sizable mansion ranked highly in the province for its quality.[7] His heirs sold the building in 1762 to Samuel Fraunces who converted the home into the popular tavern, first named the Queen's Head.
I know in the PLUTO data a lot of the entries have a year build and a number of years renovated. Even then though it appears that the year built is being used throughout the map. Probably requires an inspection of the actual row in the PLUTO data containing Fraunces Tavern.
[1] http://en.wikipedia.org/wiki/Fraunces_Tavern