This structure is impressive but I'm surprised the longest wall in the world is not even mentioned in western education
The walls of Benin were 4 times longer than the wall of China: https://en.wikipedia.org/wiki/Walls_of_Benin
The ignorance of this structure is partially due to the racism of the time and Britain's determination to erase Benin from history: https://en.wikipedia.org/wiki/Benin_Expedition_of_1897