According to UNESCO’s measured total, how long is the Great Wall of China?

According to UNESCO’s measured total, the Great Wall of China is 21,196 kilometres long.

This figure includes the full network of walls, trenches, natural barriers, and associated defensive structures built and rebuilt across different periods of Chinese history. It is not the length of one continuous stone wall visible from a single location.

The earliest fortifications date back to the Warring States period. The Qin dynasty connected and expanded earlier defenses, while the Ming dynasty constructed many of the best-preserved brick and stone sections visited today, including those near Beijing.

A commonly cited 8,850-kilometre measurement refers specifically to the Ming-era wall survey rather than the entire historical system. The Great Wall was added to UNESCO’s World Heritage List in 1987, and it is not reliably visible from the Moon with the unaided eye.