Giant Wall in China (By : Kezia)

The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally built along an east-to-west line across the historical northern borders of China in part to protect the Chinese Empire or its prototypical states against intrusions by various nomadic groups or military incursions by various warlike peoples or forces. Also known as Wall Along the 10000 Li. Several walls were being built as early as the 7th century BC; these, later joined together and made bigger, stronger, and unified are now collectively referred to as the Great Wall. Especially famous is the wall built between 220–206 BC by the first Emperor of China, Qin Shi Huang. Little of that wall remains. Since then, the Great Wall has on and off been rebuilt, maintained, and enhanced; the majority of the existing wall was reconstructed during the Ming Dynasty. This is a UNESCO World Heritage Site

Other purposes of the Great Wall have included border controls, allowing the imposition of duties on goods transported along the Silk Road, regulation or encouragement of trade and the control of immigration and emigration. Furthermore, the defensive characteristics of the Great Wall were enhanced by the construction of watch towers, troop barracks, garrison stations, signaling capabilities through the means of smoke or fire, and the fact that the path of the Great Wall also served as a transportation corridor.

The Great Wall stretches from Shanhaiguan in the east, to Lop Lake in the west, along an arc that roughly delineates the southern edge of Inner Mongolia. A comprehensive archaeological survey, using advanced technologies, has concluded that the Ming walls measure 8,851 km. This is made up of 6,259 km sections of actual wall, 359 km of trenches and 2,232 km of natural defensive barriers such as hills and rivers. Another archaeological survey found that the entire wall with all of its branches measure out to be 21,196 km.

Characteristics

Before the use of bricks, the Great Wall was mainly built from rammed earth, stones, and wood. During the Ming Dynasty, however, bricks were heavily used in many areas of the wall, as were materials such as tiles, lime, and stone. The size and weight of the bricks made them easier to work with than earth and stone, so construction quickened. Additionally, bricks could bear more weight and endure better than rammed earth. Stone can hold under its own weight better than brick, but is more difficult to use.Consequently, stones cut in rectangular shapes were used for the foundation, inner and outer brims, and gateways of the wall. Battlements line the uppermost portion of the vast majority of the wall, with defensive gaps a little over 30 cm tall, and about 23 cm wide.

Condition

While some portions north of Beijing and near tourist centers have been preserved and even extensively renovated, in many locations the Wall is in disrepair. Those parts might serve as a village playground or a source of stones to rebuild houses and roads. Sections of the Wall are also prone to graffiti and vandalism. Parts have been destroyed because the Wall is in the way of construction.

More than 60 km of the wall in Gansu province may disappear in the next 20 years, due to erosion from sandstorms. In places, the height of the wall has been reduced from more than five meters to less than two meters. The square lookout towers that characterize the most famous images of the wall have disappeared completely. Many western sections of the wall are constructed from mud, rather than brick and stone, and thus are more susceptible to erosion. In August 2012, a 30 metre section of the wall in north China's Hebei province collapsed after days of continuous heavy rains.