Great Wall of China

The giant construction of the ancient world, the Great Chinese Wall measures 21196.18 kilometres long, being even today "the longest wall on Earth". No one knows exactly which Chinese state decided to surround its territory with waves of earth and stone. In order to protect the state they had unified, the first emperor of China, Qin (221-210 BC), commands to link together the fortifications built by his predecessors. So he would continue building both east and west, with a total length of 5,000 kilometres, achieving the longest wall that would subsequently become famous. During the next dynasty, the Han (206-220 BC), the wall was again extended eastward and westward to a length of 21196.18 km. Having suffered great damage over a millennium, the Great Wall was rebuilt for about 6400 km during the Ming Dynasty (1368-1644), the dynasty that also established the capital of Beijing (the form in which it kept until today).
Winding over the mountains and hills, and also through deep valleys, the wall, which is provided from place to place with rectangular forts and towers for defence, has a height of 12 meters and a width of 6.5 meters. Paved with stone, it was used as both a strategic road and a trade route. Overgrown since the nineteenth century, the Great Wall was taken under government protection in 1952, being declared a historical monument of China. However, only a small portion of the wall was rehabilitated and it's still accessible to tourists.Less