For the Chinese people, the Great Wall is an iconic symbol of their country, but what makes the wall one of the wonders of the world is its longevity, length and the role it played as the largest defensive military construction project.
The history of the Great Wall of China is actually built on two walls. The first part was built in 200 B.C., and the final fortifications were completed in the 16th century, during the Ming Dynasty.
China built the Great Wall to help keep back marauding nomadic tribes from the north. This was not always successful, as the fierce warrior horsemen often captured Chinese citizens and carried them off to serve as slaves.
The exact length of the Great Wall of China is disputed. Some experts include ruined sections and natural barriers such as rivers and mountain divides that were incorporated into the design. Others count only the existing parts of the wall. The entire route is more than 5,000 miles from Shanghai, China, on the Pacific coast, west to the Himalayan Tibetan Plain.
The wall is 20 feet high and 20 feet wide along most of the route, and 40-foot-tall watchtowers are located every 200 yards. Among visitors, the most popular sections are those near Beijing.
It is a myth that the Great Wall of China can be seen from space, according to NASA. The local earth and stones used to build the wall blend into the surrounding landscape in photos shot from space.