Which dynasty began the first major unification of China’s Great Wall?

The Qin dynasty began the first major unification of China’s Great Wall.

After Qin Shi Huang unified China in 221 BCE, he ordered existing defensive walls in northern states to be connected and extended. These early structures were intended to defend against raids from northern peoples, including groups associated with the Xiongnu.

The Great Wall was not built as one continuous project by a single dynasty. Earlier states constructed separate walls, while later dynasties repaired, expanded, or rebuilt them. The best-preserved brick and stone sections that tourists commonly visit were constructed mainly during the Ming dynasty, centuries after the Qin period.

Another common misconception is that the wall is clearly visible from the Moon; it is not readily visible to the unaided eye from lunar distance. Its total length includes many branches and associated defensive works.