The Wall Of Darkness

The Wall Of Darkness by Arthur C. Clarke - Ages ago the First Dynasty had walled up half the planet, and left no hint of their terrible reason... Only Shervane dared to surmount that mile-high barrier, and learn the mind-shattering truth that lay beyond.Many and strange are the universes that drift like bubbles in the foam upon the river of time. Some–a very few–move against or athwart its current; and fewer still are those that lie forever beyond its reach, knowing nothing of the future or the past.