🇳🇬 Nigeria · Earthwork
Sungbo's Eredo (Ogun) – Yoruba's 160-km Earthwork Rampart
Late Iron Age / Yoruba (Ijebu) · Ijebu Yoruba (Oloye Bilikisu Sungbo tradition)
Largest single monument in Africa: 160 km curvilinear ditch-and-bank snaking 20 m deep through rainforest around medieval Ijebu kingdom (800–1000 CE, Darling charcoal).