TED-Ed: What makes the Great Wall of China so extraordinary

The Great Wall of China, a 13,000-mile structure, was initially built by feudal states to protect against invasions. Emperor Qin Shihuang unified these walls, and the Han dynasty extended them further. Despite its formidable nature, the wall was breached by Mongols. The Ming dynasty fortified it with bricks and watchtowers, but it eventually fell into disrepair. Today, the wall is a cultural symbol, attracting tourists and requiring preservation efforts. Contrary to popular belief, it is not visible from space.

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