The Mountains of Madness are a range of mountains in Antarctica, that are higher than the Himalayas. They contain vast, horrific ruins that are home to otherworldly remains.
In 1894, Captain Nemo visited the mountains during a fateful expedition. He barely escaped with his life and was the only survivor of his expedition.
The mountains are from H.P. Lovecraft's 1931 novella At The Mountains Of Madness.