I know the Great Wall of China is the longest manmade structure in the world. Is it also the longest graveyard?
--Adam, 12, Midlothian, Virginia

Dr. dig responds:
The Great Wall of China, with a surviving length of more than 1,240 miles, is actually a series of shorter fortified walls and watchtowers, built during the Bronze Age Zhou Dynasty and then linked together by the first Emperor of the Qin Dynasty, Shihuangdi. Repaired and improved over many centuries, the wall acted as a defensive border to protect the Chinese farmers from attacks by nomadic tribes. Such a massive building project needed many workers over many hundreds of years. Unfortunately, many of the workers died while working on the wall, and were buried close by. This makes the wall the longest graveyard in the world.