The great wall of China (长城), aka Chinese Wall

The Great Wall of China, called "Long Wall" by the Chinese and "Chinese Wall" by foreigners, is a series of fortifications made of stone, brick, but also other matrials such as rammed earth and wood. The wall as we can see it today has been constructed during the Ming Dynasty (1368 - 1644) and extended the older existing parts of a wall. The oldest parts of this defense structure have been date to the 7th century BC. Several kings and emporors have changed, extended and enhance the wall to fortity the wall and protect the changing borders.
The wall is primarily east-west oriented to protect the Chinese northern border. against the raids and invasions of the various nomadic groups of the Eurasian Steppe. The Great Wall stretches from Dandong in the east to Lop Lake in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. Archaeological studies have concluded that the Ming walls measure 8,850 km in total length. If all branches of the wall are included, the length totals to a stunning 21,196 km.