Mine is most likely Dante Alighieri, the author of "la Divina Commedia", as another great, Giovanni Boccaccio, put it. The Divine Comedy is particularly interesting, although i have yet to read it in depth (to my shame).
Dante tells of a journey in Holy Week, 1300, throughout the realms of the dead. He is guided through Hell (The first “cantiche” of the Divine Comedy, known as Inferno) and Purgatory (The second “cantiche”, Purgatorio) by the great poet, Virgil. He then embarks into Paradise (The third “cantiche”, Paradiso), guided by Dante's ideal of a perfect woman, named Beatrice, apparently a real woman he met in Florence. The entire journey is fraught with obstacles and amazing and terrible sights. The poem is truly epic, and even the merest flick-through of it is rather addictive.