Facts of the Present Day Great Wall of China

The Great Wall of China is one of the world's most recognizable structures. Located throughout China, the wall was originally built as a series of stone and earth fortifications. It was rebuilt and reconstructed over a time period that stretches from the third century B.C. to the 16th century and was originally intended to act as a defensive barrier to keep out attacking nomads from the north.


Record Breaker
Covering more than 4,000 miles, starting in Shanhaiguan in the east and finishing in Lop Nur in the west, the Great Wall of China is the longest man-made structure the world has ever seen. Its enormous length creates a huge surface area, making it the second-largest man-made structure ever constructed after the Fresh Kills Landfill in New York.


Defense
The Great Wall of China was more than just a wall; it was a large defensive project with numerous watchtowers, garrison towns, beacon towers and other fortifications. At its peak, the wall was protected by 1 million guards, and estimates put the human cost for building the wall over the years between 1 and 3 million lives.


Ming Wall

The oldest of the four major walls in China's history dates to the Qin Dynasty in the third century B.C., when the dynasty's first emperor connected a series of walls previously built by regional states. It was situated much farther north than today's wall. Work on the present wall commenced during the Ming Dynasty, from 1368 to1620, with work and extensions continuing as successive rulers came to power. For the first time, the wall was made of stronger and longer lasting materials, such as brick and solid stone. The main reason for the extension of the wall was to ensure that raiding nomadic Mongols could not get through and pillage Chinese land.


Materials

The first versions of the wall were made of earth, stones and wood. Tthe Ming Dynasty, however, saw the introduction of fired bricks and tiles to the building of the wall in many areas. Stone was still used in the foundation due to its better ability to absorb weight. The materials used depended on what could be produced locally. In some areas, the wall is constructed of limestone blocks and in others quarried granite that is kept together with a mixture of rice and egg whites. The western part of the wall, which lacked good local materials, is made of a mixture of soil and wood interwoven with mats.


Wonder

The Great Wall of China was included in the Seven Wonders of the Medieval World, a list that probably was drawn up after the 16th century. The wall joined the likes of Stonehenge in England, Hagia Sophia in Constantinople (modern Istanbul) and the Leaning Tower of Pisa on the list. In 1987, the Great Wall of China was added by UNESCO as a World Heritage Site.


Not Visible from Space
One of the many myths about the wall is that it can be seen from space and the moon. The myth dates to Richard Halliburton's 1938 book "Second Book of Marvels." The National Aeronautics and Space Administration (NASA) has stated that the wall certainly isn't visible from the moon and isn't even visible by the naked eye in a low Earth orbit. That is because the wall's color does not distinguish it from its surroundings.