The Great Wall of China was not built for its would-be historic value nor for the tourist attraction it earned now. Neither do other walls of the world such as the really ancient Sumerian's Amorite wall, the Walls of Constantinople, the Berlin Wall and many others including our own Harar City Wall.
Who Builds Walls and Why?
In contrary to the saying 'good fences make good neighbours', walls are evidences of distrust and hate. Sumerian's Amorite Wall was built 4,100 years ago by Sumerian rulers to keep Amorites out of Mesopotamia. Walls of Constantinople (today's Istanbul) were built in the 15th century by Byzantine empire to keep away Arab conquerors. Great Wall of China was built from the 3rd century BC to 17th century AD by the orders of kings to defend Ming dynasty and to keep northern nomadic tribes of Mongule out. Berlin wall was built in the 19th century to stop people escaping communist East Germany to the west. The difference here, it is not West Germany that blocked entry but the East prohibited exit. Harar wall of Ethiopia was built in the sixteenth century by successor of Ahmed Ibn Ibrahim, Emir Nur Ibn Mujahid to protect the Sultanate from outside invaders.