Ryubix Manor from Second Thought Games.
Available in PDF at DriveThruRPG here - RYUBIX MANOR in PDF
and in print at the Second Thought Games page here - RYUBIX MANOR in PRINT
It has a nice back history that makes it rather easy to drop into any ongoing campaign if need be. A manor built quite some time ago by the Ryubix family, three brothers who took care of those around them and were a positive influence on the area. Generations go by and each time the family line gets darker and darker until finally a curse is dropped upon both the surviving family members and the manor itself. A century later the players either acquire the deed to the manor from the last known surviving person of the family line, or are hired by him to clean it out.
All the necessary NPC's are given some detailed descriptions but are presented pretty much statless. You get a pretty rough idea of their power level with the level and class description following their names (ex. Vampire/ 15th Level Bard). The monsters are presented without stat blocks as well with just a Hit Dice rating. The author told me this is because most GM's already have the monster manuals with everything they need in them, no need to reprint them all here, raise the page count and thus the cost of the book. For those who may not have them Second Thought Games have provided the necessary stats in pdf format on their website in both Pathfinder and 3.5 D20 OGL.
The manor is bloody huge. 325 detailed areas to be exact along with details on the immediate surrounding areas and even the roof of the building. The map that comes with the book is double sided, very sturdy and well detailed. Even then not all of the areas are able to fit on it as the underground sections are in the book. It is big, very big.
But the one of the nice things is the layout all makes sense. It is laid out like a massive manor, known in the past for having balls and frequent important visitors, should be. Luxury and ease of living, along with catacombs for the burial of family members, cellars where there are storage areas for things they really would have needed to store things in. There are no random layouts in this place, no 'what the hell was this place before it became a monster filled dungeon' vibes at all.
While I haven't had a chance to run this I have heard from a few playtesters and got to read a bit of the feedback from them. It's a challenge but something that can be accomplished, so no cake walk but no useless fight with no hope of winning either. Very solid adventure that holds up to what most players can dish out.
Finally the layout and presentation is very simply. Going for more ease of use and substance than style and fancy design. It is clear, decently illustrated with no layout errors or missing sections that I have noticed. This alone gives it a bit of an old school feel, back before everyone thought things should have every bell and whistle they could push into it.
In the end this is a very well done adventure. Pretty much geared for higher level players but it is scalable so it can fit a good range of levels. The book and map are both well made and should hold together for lots of play. Second Thought Games has come out the gate with a good showing for their first offering. If their next two announced books hold up as well then people should really start to take some notice.