One of my favorite parts of living in NYC was feeling like I was walking through history. Every street, subway station and building seemed to drip with time. (some more literally than others...) That fact makes for some interesting research into the history of NYC homes. Here are a few places you might want to look for info about your cozy but no doubt, well- lived in apartment.
1. The Office for Metropolitan History Buildings Permit Database: 1900-1986 is a great resource for discovering who built your property and when.
It was here that I found out that the building above my favorite deli was built in 1906 for $250,000.
2. Land Conveyances - A conveyance is simply the deed to a piece of property. The New York Public Library has indexes if you want to look up your address (or New York property owner ancestor)
You can also check out the index and then look up the actual deeds on microfilm at the city office.
3. The Real Estate Record and Guide (1868-1922), digitized and made available free online by Columbia University, is a useful and nerd-fabulous. I found the announcement of the plans for building the Hudson River Bridge in 1868. Like I said - nerdfabulous.
If none of these things work - I would head down to the NYPL library and ask one of their many super knowledgeable employees for some advice - because like everything associated with New York bureaucracy - there are a million (or something close to a million) different locations to find the info you need.