The Benin Walls are a series of defensive earthworks surrounding the city of Benin City in present-day Nigeria. Originally built in the 13th century, these walls were constructed to protect the city from invaders and to control trade. They are among the largest man-made structures in the world, stretching over 16,000 kilometers in total length. The walls were made primarily from earth and were reinforced with moats and ditches. They played a significant role in the history of the Benin Kingdom, showcasing the advanced engineering skills of the Edo people. Today, the Benin Walls are recognized as a UNESCO World Heritage site, highlighting their cultural and historical importance.