Author: Riccardo Hu
The Great Wall of China, Wànlǐ Chángchéng (万里长城), consists of a series of fortifications built across the northern borders of China and it is one of the largest building projects ever undertaken in history. The total length of all sections adds up to 21,196 kilometers, with an average height and width of respectively around 8 and 5 meters.
The construction started around 221 B.C, commissioned by Qin Shi Huang of the Qin dynasty, the first emperor of unified China. By connecting and extending the separate walls previously built, his objective was to consolidate the state and build fortifications as protection against various nomadic groups and as border control. Needless to say, it was also a way for China to show its majesty and prominence.
Later on, it will undergo many other reconstructions by other dynasties, the most famous by the Ming dynasty between 1368 and 1644.
While nowadays it is mainly a tourist attraction, in Ancient times, due to its defensive characteristics, the Great Wall was enhanced by watchtowers, troop barracks, and garrison stations. Communication between watchtowers occurred through a signaling system based on the use of smoke or fire to alert soldiers of an invasion or attack.
Despite, over the years, many sections of the wall have deteriorated, the Great Wall is still considered by many one of the greatest achievements in human architecture. As of today, it is one of the most notorious attractions worldwide, listed as one of the seven wonders of the modern world, and recognized as a world heritage site by UNESCO in 1987.
Fun fact: A popular space myth about the Great Wall says it is the only man-made structure visible from space. Nasa itself dispels this myth stating no man-made object is visible at that scale. In particular, the materials used for the wall are similar in color and texture to the materials of the land surrounding it, making it even harder to distinguish it in astronaut photography.