A damaged part of The Great Wall, near Badaling.

BADALING, CHINA - 1993/02/01: A damaged part of The Great Wall, near Badaling. Construction of The Great Wall started during the warring states period in the 7th century B.C.. This period lasted more than 2,500 years. The Ming Dynasty was the last dynasty in Chinese history to undertake large scale construction of the Great Wall. Most of the walls we see today were built in the Ming Dynasty. The Ming Great Wall stretches from the Yalu River in the east to Jiayuguan in the west, covering a total length of more than 5,000 Km. (Photo by Gerhard Joren/LightRocket via Getty Images)