|The Great Wall of China is a series of stone and earthern fortifications, built, rebuilt and maintained between the 6th century BC and the 16th century to protect the northern borders of the Chinese Empire from Xiongnu attacks during the rule of successive dynasties. Several walls, referred to as the Great Wall of China, were built since the 5th century BC. The most famous is the wall built between 220-200 BC by the first Emperor of China, Qin Shi Huang; little of it remains; it was much farther north than the current wall, which was built during the Ming Dynasti.
The Great Wall stretches over approximately 6,400 km, from the boundary with Korea in south to the Gobi desert. At its peak, the Ming Wall was guarded by more than one million men. It has been estimated that somewhere in the range of 2 to 3 million Chinese died as part of the centuries long project of building the wall.
While some portions north of Beijing and near tourist centers have been preserved and even reconstructed, in many locations the wall is in disrepair. No comprehensive survey of the wall has been carried out, so it is not possible to say how much of it survives, especially in remote areas.
Sections worth visiting are: the Juyongguan pass (the North Pass), this section of the wall is made of stones and bricks from the hills and is 7.8 meters high and 5 meters wide, build to defend Beijing. Jiayuguan pass (west pass), this section is near the western edges of the Great Wall. Shanhaiguan pass (eastern pass), this section is near the eastern extremity of the wall, and the first mountain the Great Wall climbs.