The Haunting of Hill House, Shirley Jackson
No living organism can continue for long to exist sanely under conditions of absolute reality; even larks and katydids are supposed, by some, to dream. Hill House, not sane, stood by itself against its hills, holding darkness within; it had stood so for eighty years and might stand for eighty more. Within, walls continued upright, bricks met neatly, floors were firm, and doors were sensibly shut; silence lay steadily against the wood and stone of Hill House, and whatever walked there, walked alone.
I know absolutely nothing about this book, other than the fact it is considered a classic of the genre, and most people I know who've read it, rave about it.
I've deliberately skipped the introduction, because while Penguin always have top rate scholarly discussions of the classics, they are also pretty spoilerish and I want to read this without knowing what's going to happen.