“Medusa’s Coil” (1930)
Read in 2018.
I can’t tell you now whether it’s an exterior or an interior—whether those hellish Cyclopean vaultings are seen from the outside or the inside, or whether they are indeed carven stone and not merely a morbid fungous arborescence.
The language is pretty in places, but this is arguably the most racist of Lovecraft’s stories. There are references to Kadath, Cthulhu etc., and there is a monster made of sentient hair, but those seem incidental. The sense of horror is supposed to come instead from the decay of an idyllic slave-owning Southern estate standing in for “The Fall of the House of Usher” (1839), its doom sealed by the unknowing marriage of its pinkish-beige scion to a marginally more brown-skinned person. The sheer length of the narrative built upon that foundation makes it seem more deeply hateful than “The Horror at Red Hook” (1927).