Excerpts from The Festival by H.P. Lovecraft.

Part 1 of 2.

After more aeons of descent I saw some side passages or burrows leading from unknown recesses of blackness to this shaft of nighted mystery. Soon they became excessively numerous, like impious catacombs of nameless menace; and their pungent odour of decay grew quite unbearable. I knew we must have passed down through the mountain and beneath the earth of Kingsport itself, and I shivered that a town should be so aged and maggoty with subterraneous evil.

...

As the steps and the passage grew broader, I heard another sound, the thin, whining mockery of a feeble flute; and suddenly there spread out before me the boundless vista of an inner world—a vast fungous shore litten by a belching column of sick greenish flame and washed by a wide oily river that flowed from abysses frightful and unsuspected to join the blackest gulfs of immemorial ocean.