In some ways, Benin City is like dozens of other fast-growing cities in Nigeria. Buoyed by burgeoning industrial and agricultural sectors, the city’s population rose by 1.7 million people over the past four decades as its footprint on the West African landscape expanded several times over.
Amid bustling new networks of roads, residential neighborhoods, markets, and workshops, lie signs of a much earlier era, when the city was the seat of a powerful pre-colonial kingdom. Remnants of ancient earthworks, thought to be among the longest in the world, can even be seen in images of the city captured from space.
Benin Iya (sometimes called the Benin Earthworks, the Walls of Benin, and the Benin Moat) is a vast, cellular network of interlocking earthen walls, ramparts, and ditches that radiate outward from a central moat at the heart of the city. Built in sections over hundreds of years between the 7th and 14th centuries, the system was key to marking defensive, political, and economic boundaries and played an important role in maintaining order and stability in the Kingdom of Benin.
The OLI-2 (Operational Land Imager-2) on Landsat 9 captured this image of the remains of earthworks on January 11, 2025. The features appear as dark green lines that trace arcing patterns in a densely settled area near the airport on the west bank of the Ikpoba River. Trees and vegetation growing in the moats give the features a dark green color.
Most of the earthworks consisted of relatively narrow and shallow linear ramparts and ditches that spread widely across the landscape. Many sections have been destroyed or are too small or too obscured by modern development to be easily dete …