The Divine Comedy
Author: Dante Alighieri
Released: The earliest manuscripts date back to the 1330s.
It's the ultimate "epic," not to mention one of the most influential works of fiction ever written. In the form of a gargantuan poem, Dante Alighieri's The Divine Comedy, broken up into three sections (Inferno, Purgatorio, and Paradiso), covers the entire spectrum of life: Hell, Purgatory, and Paradise, all seen through the eyes of protagonist Dante.
With such a massive scope, it's all the more remarkable how Alighieri keeps The Divine Comedy intimately grounded as a character study, which is why we'd curse the bastards who'd ever try to translate it to the big screen. Some works of literature are just too good for multiplexes.
Fun Fact: The entire poem was written over the course of eight years, leading up to 1321, when Alighieri died at the age of 56.