The Great Wall was mainly built with masonry, rocks, and packed earth. It's thickness ranged from about 4.5 to 9 meters (15-30 feet) and was up to 7.5 meters (25 feet) tall. During the Ming Dynasty from 1368-1644, the Great Wall was enlarged to 6,400 kilometers (4,000 miles). The wall was rebuilt over a 200 year period, with watch towers added every 1.5 miles, in all there would be 25,000 towers built being about 40 feet, there were guard posts every 3 miles, fortresses every 9 miles miles, and barracks every 31 miles.

The Great Wall can be seen from the Earth's orbit, but it cannot be seen from the moon according to astronauts Neil Armstrong, Jim Lovell, and Jim Irwin.

This wall consists of two paralell wall 10 meters (33 feeet) and is built with stone, brick, and packed earth.