Originally Posted by mono
Hmmm, a few of my favorites that come to mind:
John Milton's Paradise Lost and Paradise Regained,
Dante Alighier's Inferno, Purgatorio, and Paradiso of The Divine Comedy,
The Oedipus trilogy of Sophocles,
Alice's Adventures in Wonderland, Through the Looking Glass, and What Alice Found There by Lewis Carroll,
The Chronicles of Narnia by C.S. Lewis.
I know I have more in this weary brain of mine, but cannot think of them presently; I will come back when I regain my thinking. :p
Good luck!