The Night Land (Unabridged‪)‬

In the distant future, the sun has burned out, plunging the world into perpetual twilight. All of the remaining humanity has dwindled to a single, eight-mile-high pyramid called The Last Redoubt. Horrific creatures have evolved that lurk in the darkness. After a second dying Lesser Redoubt is discovered, one man is determined to rescue its last surviving inhabitant, but that means traversing the unknown and terrifying Night Land.

First published in 1912, The Night Land was hailed by H.P. Lovecraft as "one of the most potent pieces of macabre imagination ever written."