The Great Wall of China has long been seen as an engineering feat not to be replicated. To think that this was built in the 7th Century B.C., by man and only by hand is amazing.
There have been satellite photos of the Great Wall from space and reports that it can be seen from the moon.
The Badaling section is northwest of Beijing. It was built at the beginning of the Ming Dynasty. There are battle forts at important points. At night, Badaling is illuminated.
South of the Badaling section is the Pass of Conscripted Laborers or Juyongguan. Built in the 1300's, Cloud Terrace was the base of a pagoda overlooking the main road of the town. There are intricate carvings of animals, flowers, and heavenly kings as well as charms in six languages.
Seventy kilometers northeast of Beijing, is the Mutianyu section of the Great Wall. It is considered one of the best sections and has battle forts built on the summit hills.
The Mutianyu section is crenellated for observing and shooting at an invading enemy.
Another section northeast of Beijing is the Jinshanling division, which is part of the Gubeikow section. There are portions that bear the scares of battles in ancient times. The battle forts are built along a mountain ridge in order to see invading forces from the high terrain.
To the east of Jinshanling is the Simatai division. This section is 3,000 meters long, and rises and falls with a precipitous mountain ridge with battle forts located high in the hills.
The purpose of the Great Wall was to warn citizens of invading forces - either by smoke or by fire. Gunshots were fired at the same time, thus relaying the alarm over 500 kilometers in just a few hours time.