You can look it up yourself on the Department of Buildings website.
Go here:
Department of Buildings. On the right side, enter in the address you want to look up.
Once it brings up the building, scroll to the bottom where it lists the Complaints, Violations, Jobs, etc. Below that there's a drop box with a bunch of other things. Click on it and select "NB - NEW BUILDING", then click "Show Actions". You may see a list of a few things come up, but one of them will say "NEW BUILDING" and have a code to the left that should read something like this "NB 1711-89*".
The last two digits are year the building was built. If there's an asterisk, it means the building was built pre-1900. For example, I used my building's code, which I know was built in 1889.
Hope this helps.