 If one were to mention the incredible feats of engineering undertaken by our now lost ancient ancestors, in particular, gigantic walls, some may lean towards the impressive, sheer enormity of the megalithic stones within the Wall of Gornaya Shoria. Or more commonly, the Great Wall of China is the more popular choice, or the more obscure, lesser-known Great Wall of India. Undoubtedly, the Great Wall of China was a feat of monstrous proportions, having been built to such a scale it's visible from space. Yet what many more are unaware of is an ancient kingdom once located in southwestern Nigeria. Known as the Walls of Benin, they dwarf the Walls of China, a series of defensively constructed earthworks called Aya in Edo. They consist of 9.3 miles of inner-city walls and an estimated 9,900 miles of outer wall. The Walls of Benin City were described as, quote, the world's largest earthwork carried out prior to the mechanical era, end quote, by the Guinness Book of Records. The Benin City Walls have been known of by Westerners since around the 1500s. Portuguese explorer Duarte Pacheco Pereira briefly described the Walls during his travels. Another description was given around 1600 by the Dutch explorer Derrick Reiders. Reiders' account of the Walls is as follows, quote, at the gate where I entered on horseback I saw very high, very thick walls of earth with a very deep broad ditch around. They were dry and full of high trees. Who built these walls? Or indeed, how did they accomplish such a mind-boggling feat? Traditional accounts suggested that assuming a 10-hour workday with a labor force of some 5,000 men, it could have been completed within just 97 days. However, these estimates have been criticized over the years in many ways, one in particular, being a lack of account for the time it would have taken to extract earth from ever-deepening holes. Yet, regardless of these discrepancies in opinion, regarding the challenge in its creation or indeed their age or origin, we find these walls highly compelling.