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.