A very long defence
Chinese rulers built the Great Wall chiefly to defend their northern frontiers against invasion. Its walls belonged to a larger system of towers, fortresses and passes.
That famous name makes it sound like one enormous building project. The real story involves different rulers, earlier defences and a great deal of rebuilding.
Some walls were already old
UNESCO describes how Qin Shi Huang joined earlier fortifications around 220 BC. Existing sections became part of a connected defence system.
Picture adding pieces to a very long puzzle. The work did not begin with an empty landscape and finish with every brick in place.
Many generations picked up the job
Building continued under later dynasties, including the Ming dynasty, from 1368 to 1644. Its construction history stretches across centuries, rather than one ruler’s lifetime.
That is why “When was the Great Wall built?” needs more than a single date. Different parts have different histories.
Look past the bricks
Next time you see a photograph, look for towers and passes as well as the wall itself. UNESCO’s description includes these different parts of the military system.
For another ancient building puzzle, discover why Roman concrete can last so long. History has plenty of surprises hiding in its building materials.
Explore ten short history surprises whenever you fancy another short read.