The Edo capital of Benin City was ringed and subdivided by a vast network of earthen ramparts and ditches, dug by hand and built up from excavated spoil. Together the city and its surrounding rural enclosures comprise thousands of kilometres of interconnected earthworks, by some estimates among the largest man-made earthen structures of the pre-mechanical world. Within, the city was laid out on a broadly planned arrangement of wide streets and walled compounds organised around the royal palace and the workshops of specialist craft guilds. The bronze-casters' guild produced the celebrated Benin plaques.
Benin's earthworks show monumental African urban engineering and planned, guild-organised city form on a scale that long predates and rivals European examples.