The construction of the Great Wall began in 221 B.C. under the Qin Dynasty. This section of the wall reached 10,000li (A li us about one third of a mile.) Later Dynasties added to this wall, the last Dynasty to add was the Ming Dynasty.
The Great Wall of China is one of the Seven Wonders of the World at 1500 miles long, 15 to 30 feet in width, and 15 to 50 feet tall.

This story shows the human cost of building the great wall There is a traditional story about Meng Jiangnü. Shortly after she and her husband were married he was conscripted to work on the wall. Meng Jiangnü worried that he would suffer from the cold in the north and began to make a padded cotton jacket. After it was sewn she began the long walk from her home in the south to the site of the Great Wall. When she got there and finally found the other men from her village, she was told that her husband had died. She went to the wall and began keening and mourning with such pathos that 20 li of the wall collapsed and in the pit at the center, she found the body of her husband. Meng Jinagnü threw herself into the sea to join her husband. Her suicide personalizes the losses due to the Great Wall.

Throughout the centuries, armies were garrisoned along the length of the Wall to provide early warning of invasion and a first line of defense. Great piles of straw and dung used to build signal fires have been found during excavations. There must have been small garrison towns spotted along the length. There weren't many farms or trade towns to provide ease, relaxation and food. The supply trails were over mountains along narrow paths. To bring supplies to the top, ropes were slung over posts set in the Chinese side of the wall and baskets were hauled up hand over hand. Supplies must have always been short and chancy, particularly in the winter. The Wall served well. Only when a dynasty had weakened from within were invaders from the north able to advance and conquer it.