Sungbo's Eredo

Sungbo's Eredo is a rampart or system of walls and ditches that is located to the south-west of the Yoruba town of Ijebu-Ode in Ogun state, southwest Nigeria (6.787°N, 3.87488°W). It was built in honour of the Ijebu noblewoman Oloye Bilikisu Sungbo, and is reputed to be the largest single pre-colonial monument in Africa.

Description
Total length of fortifications is more than 160 km. Fortifications consist of a ditch with unusually smooth walls and bank in the inner side of ditch. The height difference between the bottom of the ditch and the upper rim of the bank on the inner side can reach 20 m. Works have been performed in laterite, a typical African soil consisting of clay and iron oxides. Ditch forms an uneven ring around the area of ancient Ijebu state, an area approximately 40 km wide in north-south, with the walls flanked by trees and other vegetation, turning the ditch into green tunnel. As a construction project, it required more earth to be moved than the Great Pyramid of Giza.

History
The Eredo served a defensive purpose when it was built in 800–1000 AD, a period of political confrontation and consolidation in the southern Nigerian rainforest. It was likely to have been inspired by the same process that led to the construction of similar walls and ditches throughout western Nigeria, including earthworks around Ile-Ife, Ilesa, and the Benin Iya, a 6500 km series of connected but separate earthworks in the neighboring Edo-speaking region.

Sungbo's Eredo has also been connected with the legend of the Queen of Sheba which is recounted in both the Bible and Koran. In the Old Testament, she is described as having sent a caravan of gold, ivory and other goods from her kingdom to King Solomon. In the Koran she is an Ethiopian sun worshiper named Bilqis involved in the incense trade who converts to Islam. Legends of the contemporary Ijebu clan link the Eredo to this fabled woman, a wealthy, childless widow who they know as Bilikisu Sungbo. According to them, the monument was built as her personal memorial. In addition to this, her grave is believed to be located in Oke-Eiri, a town in a Muslim area just north of the Eredo. Pilgrims of Christian, Muslim and traditional African religions annually trek to this holy site in tribute to her.

It is believed that the Eredo was a means of unifying an area of diverse communities into a single kingdom. It seems that the builders of these fortifications deliberately tried to reach groundwater or clay to create a swampy bottom for the ditch. If this could be achieved in shallow depth, builders stopped, even if only at the depth of 1 meter. In some places small, conical idol statues had been placed on the bottom of the ditch.

The impressive size and complex construction of the Eredo drew worldwide media attention in September 1999 when Dr Patrick Darling, a British archaeologist then with the University of Bournemouth, surveyed the site and began publicizing his bid to preserve the Eredo and bring the site some prominence. Previously, the Eredo had been little-known outside of the small community of residents and specialists in Yoruba history. Forty years passed between Professor Peter Lloyd's publication of his analysis of the site and that of Darling, but it still served to necessitate a complete rethinking of West Africa's past.

World Heritage Status
This site was added to the UNESCO World Heritage Tentative List on November 1, 1995 in the Cultural category.