Benin Kingdom Constructs World's Largest Earthwork System

The Edo people of the Benin Kingdom construct a network of defensive earthworks, moats and ramparts, eventually extending over 10,000 miles across the forest of southern Nigeria. Begun around 900 CE and expanded over centuries, the Benin Walls are estimated to have required more earth-moving than the Great Wall of China and are among the largest pre-mechanical engineering feats in human history.