Longest earthworks of the pre-mechanical era

Longest earthworks of the pre-mechanical era
Who
The Ancient Linear Earthworks of Benin and Isha
Where
Nigeria ()
The longest earthworks in the world carried out prior to the mechanical era are the Ancient Linear Earthworks of Benin and Ishan, located in Edo State in present-day Nigeria. In 1977 it was estimated by Dr Patrick Darling that the total length of the earthworks was probably 16,000 km (10,000 miles) with the total amount of earth moved estimated at 150 million m³ (200 million yd³).