What is the approximate total length of China’s Great Wall system?

China’s Great Wall system has an approximate total length of 21,196 kilometers. This figure comes from a large national survey that counted walls, trenches, natural barriers, and related defensive sections from different periods.

The Great Wall is not one continuous structure built at one time. Earlier states built defensive walls before the Qin dynasty unified sections in the third century BCE. Later dynasties repaired or expanded the system, and many of the best-preserved sections visible today date from the Ming dynasty, which ruled from 1368 to 1644.

The wall’s purposes included defense, border control, signaling, and regulation of movement and trade. A common misconception is that it can be seen from the Moon with the unaided eye; this is not true. Its total length also differs among sources because researchers use different definitions of what counts as part of the wall system.