How long is the complete Great Wall of China according to China’s official survey?

The complete Great Wall of China measures 21,196 kilometres according to China’s official survey.

China’s State Administration of Cultural Heritage announced the figure in 2012 after a nationwide archaeological survey. It includes not only famous masonry walls but also trenches, natural barriers, and remains from multiple historical periods. The much smaller figure often quoted for the Ming-era wall is about 8,850 kilometres.

The Great Wall is not one continuous structure built at one time. States in ancient China constructed earlier defensive works, while the Qin dynasty linked and expanded sections in the third century BCE. The Ming dynasty later built, rebuilt, and fortified extensive stretches, many of which are the stone and brick sections visited today.

Contrary to a popular myth, the wall is not plainly visible from the Moon with the unaided eye. Its purpose varied by period, but watchtowers, beacon systems, garrisons, and gates helped monitor movement and defend strategic routes.