The Benin Empire was one of the oldest and most highly developed states in west Africa. The Walls of Benin City, originally known as Edo and located in present-day Nigeria, were the world’s largest man-made earth structure. It took an estimated 150 million hours of digging to construct and is perhaps the largest single archaeological phenomenon on the planet. Large portions of the walls were destroyed by the British in 1897. | Unsolved Mysteries & Paranormal Activities