Pictures of Beacon Towers of Great Wall, the Signal System

As the important military defenses, the Beacon Tower, the oldest but effective telegram of China, is a high tower used for lighting fire to pass message in ancient China. It was built to prevent the invasion of the enemies. When the enemies came, smoke and fire on the beacon towers would be lit at daytime and at night respectively one after another to pass the enemy's situation or movement and to get the aid from the military administrations. Related Intro: Beacon Towers of Great Wall