A while ago I wrote about an upcoming Frog God product that's now released. It's a dungeon from 1981 that was shut down before release due to TSR legal action, and which we're now publishing. This is the authentic stuff (well, the S&W version is, the Pathfinder one is obviously re-done for Pathfinder).
Bill has a description of the history of the Black Monastery on the Frog God site HERE. Note that part of the description is written for younger gamers who may not be familiar with what they're going to find in there. Old schoolers can get by with: "it works a lot like Tegel Manor does."
It's a stitched hardback, and I think it has one or more poster maps, but I can't remember exactly. I don't remember if it's a fold-out map, or separate, or what. The price tag is $34.99 for the book + pdf, or $15.99 for the pdf alone.
But the point being, this is basically a piece of lost D&D from the hidden cabinet of the past. Pretty cool stuff.