At the Mountains of Madness is a novella by horror writer H. P. Lovecraft.
The story details the events of a disastrous expedition to the Antarctic continent in September 1930, and what was found there by a group of explorers led by the narrator, Dr. William Dyer of Miskatonic University. Throughout the story, Dyer details a series of previously untold events in the hope of deterring another group of explorers who wish to return to the continent.
The novella's title is derived from a line in "The Hashish Man," a short story by fantasy writer Edward Plunkett, Lord Dunsany: "And we came at last to those ivory hills that are named the Mountains of Madness..."
The story has inadvertently popularized the concept of ancient astronauts, as well as Antarctica's place in the "ancient astronaut mythology".
The story is told in a first-person perspective by the geologist William Dyer, a professor at Miskatonic University, in the hope to prevent an important and much publicized scientific expedition to Antarctica. Throughout the course of his explanation, Dyer relates how he led a group of scholars from Arkham's Miskatonic University on a previous expedition to Antarctica, during which they discovered ancient ruins and a dangerous secret, beyond a range of mountains higher than the Himalayas.