Take a taxi one hour north of Lagos to see Sungbo's Eredo, Africa's largest pre-colonial construction and a sight rated by experts as an unknown "Wonder of the World". The Eredo is a rampart that is 1,050 years old, 100 miles (160km) long, and 70ft (20m) high. Locals will need to guide you in and out as the structure is rapidly being covered by encroaching forest. The building of Sungbo's Eredo required more earth to be moved than during the construction of the Great Pyramids at Giza. The Eredo may have been built as a memorial to Bilikisu Sungbo, a childless widow, whose grave is nearby.