Over in Southeast Asia, the landlocked nation of Laos remains one of the least-explored areas in the region, even today. And those few outsiders fortunate to travel to this country may encounter a mystery that's baffled investigators for centuries (if not millennia): What is the Plain of Jars? What could have inspired ancient civilizations to build hundreds upon hundreds of giant, stone jars out in northern Laos? Why did the US government spend so much time planting bombs in the area?