Thanks everyone for the input. i know it was a mistake not to do the survey. Nobody asked me and I should have brought it up. It was a cash deal so no lender to scrutinize. The contract does not list the map parcel, it lists the meets and bounds description.
I went to the city today with cash in hand to pay the back taxes, but they refused my $ and told me it was sent to an attorney for foreclosure (which seemed to imply their hands were tied). The supervisor in the Real Estate Tax dept took pity on me and gave me the direct phone number of the attorney who had the case. My title agent is trying to reach him now.
The house is waterfront and still has value without the driveway. But I am hoping it does not go that way. (The adjacent lot, fwiw, is not large enough to build on so a purchase would be purely to torture us.) I know, it can happen.
Our title agent, who did the closing, is doing everything she can to fix this. I posted because it's a great story about why you pay the freakin $200 for a title search, and why you need to check things yourself and not leave them to your agent or title agent. Incidentally, I like them both very much and would work with them again.