The Walls of Benin City: One of the Largest Earthworks Ever Built

Today, if you drive through Benin City in southern Nigeria, you might pass a deep ditch overgrown with vegetation, or a long, low mound of earth running beside a road. It would be easy to miss. But these are the remains of one of the most extraordinary building projects in human history: the walls and moats of the Kingdom of Benin, a network of earthworks so extensive that some researchers have estimated their total length in the thousands of kilometres.

The Kingdom of Benin

The Kingdom of Benin, centred on Benin City in what is now Edo State, Nigeria, was one of the most powerful states in West Africa from around the 13th century until British conquest in 1897. Ruled by a sacred king, the Oba, it was famous for its royal court, its guilds of craftsmen and its magnificent works of art, including the bronzes described in our story on the Benin Bronzes.

The walls and moats

The earthworks of Benin are known in the Edo language as iya. They consist of ditches (moats) and earthen banks (walls), built by digging deep trenches and piling the earth beside them.

There were two main kinds:

• The city walls — around Benin City itself, a massive inner wall and moat defended the capital. Early European visitors described the deep moat and high bank, and the impressive gates.
• The rural earthworks — a vast network of walls and ditches surrounding hundreds of villages and towns across the Benin region, marking boundaries between communities and their farmlands.

The British archaeologist Patrick Darling, who surveyed the earthworks over many years from the 1960s onward, estimated that the total length of the walls and moats across the region was around 16,000 kilometres, enclosing hundreds of communities. Writing about his findings in 1999, New Scientist described them as potentially the largest earthworks in the world, longer than the Great Wall of China in total length and requiring an enormous amount of labour. Estimates vary, and much remains to be studied, but there is no doubt about the scale.

How and why were they built?

The earthworks were built over many centuries, perhaps beginning around the 9th or 10th century and continuing into the 15th century and beyond. They were dug by hand, probably by many communities working over long periods, rather than as a single project.

Their purposes likely included:

• Defence — protecting settlements from attack and wild animals.
• Boundaries — marking the territory of each village or clan and its farmlands.
• Spiritual protection — some traditions associate the walls with spiritual meanings.
• Political control — the inner city walls symbolised and protected the power of the Oba.

A city admired by visitors

European visitors who reached Benin City from the late 15th century onward were impressed. A Dutch description from the 17th century, often quoted, describes a large city with broad, straight streets, a vast royal palace with many courtyards, and orderly houses. Benin City was well planned and organised.

Destruction

In 1897, a British military expedition attacked Benin City, burning much of the city and the royal palace, and looting thousands of artworks. In the following century, much of the old city's layout and many of its earthworks were destroyed or damaged by urban growth, road building and neglect. Today, sections of the moat and walls survive, some protected, others threatened by development.

There have been calls to protect the remaining walls and moats, and to seek recognition for them as heritage of global importance.

Why it matters

The walls of Benin are a powerful reminder that some of the largest construction projects in human history were built in Africa, by African communities, over centuries. They show sophisticated organisation, engineering and planning. Yet because they were built of earth rather than stone, and because colonial narratives ignored them, they have been largely forgotten. Rediscovering them is part of rediscovering the true scale of Africa's past.

Further reading

• Patrick J. Darling, Archaeology and History in Southern Nigeria: The Ancient Linear Earthworks of Benin and Ishan (BAR International Series, 1984)
• Graham Connah, The Archaeology of Benin (Clarendon Press, 1975)
• Fred Pearce, "The African Queen," New Scientist (11 September 1999)