The Great Wall of China is the largest defensive work people have ever built.
It runs 13,170.7 miles (21,196.18 kilometers). Maps make it look like one unbroken line through the mountains. It is not.
The total counts walls, trenches, and natural barriers from different dynasties. It also counts sections rebuilt on top of older ones.
A trench is a canal dug in front of the wall. A natural barrier is a mountain or steep slope that stopped an army by itself.
These parts cross 15 provinces, autonomous regions, and municipalities.
The number comes from the first scientific survey of every section. The State Administration of Cultural Heritage and the State Bureau of Surveying and Mapping released it in 2012.
The work took six years.
Earlier counts stuck to the best-preserved Ming dynasty stretch, about 5,499 miles (8,850 kilometers).
The full length is longer than half the way around Earth at the equator.
Building started more than 2,200 years ago.
This is not only stone on a ridge. On a steep slope, the mountain was the defense, and it is part of the total.
The old figure covers one dynasty.
The new one measures centuries of building.
Enjoyed the story?
Follow Colossal Facts for a new story every day.
Or watch them as short videos on Facebook →
