Four thousand years ago, a mysterious pagan society called the Hittites dug deep into the soft volcanic rock, called tufa, to carve out an intricate underworld. But after almost 800 years of rule, the Hittite Empire vanished without a trace. Where did their people go and what clues have they left behind in their complex subterranean world of Cappadocia?

What was the secret to the success of ancient Rome? Aqueducts, underground neighborhoods, and one of the oldest sewer systems reveal many secrets. The largest and most influential empire in history leaves clues to her greatness under nearly every street.