The Great Wall of China is a system of several segments, repeatedly modified over time to prevent invasions from raider tribes. Despite its legendary visibility from space, it's actually the world's largest monument, with an elaborate system of garrison towers, advanced tower posts, and communication systems.
Secret History
The ancient Great Wall of China's construction techniques and origins are revealed in this documentary, delving into the methods used before the 16th Century and the reasons behind its initial construction.
