When people talk about places worth visiting in Nigeria, the conversation usually revolves around beaches, waterfalls, game reserves or ancient city walls. Very few people mention Sungbo’s Eredo.

That is surprising because this extraordinary monument is not just one of Nigeria’s greatest historical treasures. It is also one of the largest ancient earthworks in the world.

Stretching for about 160 kilometres through the forests and communities around Ijebu-Ode in Ogun State, Sungbo’s Eredo is a vast network of deep ditches and towering earth embankments built centuries before modern construction equipment existed. Every section was dug by hand using simple tools, yet the scale of the project continues to amaze historians and archaeologists.

Even more remarkable is that researchers are still trying to answer the biggest questions surrounding it. Who built it? Why was it built? And why has such an extraordinary place remained largely unknown outside southwestern Nigeria?

More than an ancient ditch

The word Eredo means earthwork or enclosure. Unlike the stone walls associated with many ancient civilisations, Sungbo’s Eredo was carved directly into the earth. Builders dug enormous trenches and piled the excavated laterite soil into towering embankments, creating a defensive barrier that rises nearly 20 metres in some places.

Researchers have debated its age for decades. Some archaeological evidence dates it to between the ninth and eleventh centuries, while other studies place its construction between the late fourteenth and early fifteenth centuries. Regardless of the exact date, scholars agree it ranks among the most ambitious engineering projects in pre-colonial West Africa.

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Its sheer scale suggests that the ancient Ijebu Kingdom possessed sophisticated leadership, organised labour and the ability to mobilise thousands of people over many years. Long before modern conversations about infrastructure, the builders had already demonstrated remarkable planning and engineering skills.

The legend behind the earthwork

The monument is named after Oloye Bilikisu Sungbo, a wealthy woman remembered in Ijebu oral tradition. Many believe she commissioned the earthwork or that it was built in her honour. Others link her to the biblical and Quranic Queen of Sheba, known in Islamic tradition as Bilqis.

While the story remains an important part of the site’s identity, historians say there is no archaeological evidence proving Bilikisu Sungbo and the Queen of Sheba were the same person. Even so, the legend continues to attract visitors to her reputed burial site at Oke-Eiri.

Many mysteries also remain. Archaeologists believe the earthwork may have served as a defensive barrier, territorial boundary and ceremonial site, although research is still ongoing.

Why Sungbo’s Eredo still matters

Modern technology is helping researchers uncover new clues. Using LiDAR, a laser-mapping technology capable of penetrating dense forest canopies, archaeologists have traced sections of the monument that had remained hidden for centuries. The findings are expected to provide deeper insights into how it was built and how communities lived around it.

Beyond its archaeological importance, Sungbo’s Eredo challenges the long-held belief that Africa lacked large-scale engineering before colonial rule. It demonstrates that sophisticated societies in what is now southern Nigeria planned and executed massive construction projects centuries ago.

Despite its significance, Sungbo’s Eredo remains one of Nigeria’s least-visited historical sites. Thick vegetation and limited tourism infrastructure mean many Nigerians are unaware it exists. The monument has been on Nigeria’s UNESCO Tentative List since 1995, recognising its outstanding cultural value and its potential for World Heritage status.

For travellers, that sense of discovery is part of the attraction. There are no crowds or long queues, only the chance to explore a place that continues to puzzle historians while preserving the legacy of one of Nigeria’s greatest civilisations.

Sungbo’s Eredo is more than an ancient earthwork. It is a reminder that some of Nigeria’s greatest stories are still waiting to be fully uncovered.

Meiza Nigeria