The House on the Borderland

Two men on a fishing trip in Ireland come across the ruins an old house, and inside that house they find the journal of a man known as The Recluse. The journal records his last days, and tells the story of how he finds himself transported to another realm where a larger version of his house stands, though it's made of jade-like substance. This arena, known as the Plain of Silence is populated by humanoid swine creatures with a craving for human flesh.

The House on the Borderland is a classic horror fantasy, and was a heavy influence on H.P. Lovecraft, Clark Ashton Smith, and all the horror writers who came after them. If you haven't read it, you're missing on on a chilling experience.