What is the name of the longest wall in the world, located in China?

The longest wall in the world, located in China, is the Great Wall of China.

The name refers to a vast series of defensive walls, fortifications, trenches, passes, and related structures built across northern China. Rather than being one continuous wall from a single period, it developed over more than two thousand years as Chinese states and dynasties responded to threats from the Eurasian Steppe.

Some of the earliest walls date to the 7th century BCE. The Qin dynasty connected earlier sections, while the best-preserved and most recognizable stretches were built or rebuilt during the Ming dynasty, from 1368 to 1644. Modern surveys estimate the combined wall sections and associated defenses at about 21,196 kilometers.

The Great Wall was not an impenetrable barrier and was also used to control movement, trade, and border traffic. A common myth says it is visible from the Moon with the naked eye; its narrow, earth-colored structures are generally too difficult to distinguish at that distance.