China would wait another 1,300 years before embarking on its greatest period of wall building. The Ming Dynasty built much of what remains today. They were driven by desperation to build the ultimate defense and lock the northern frontier once and for all. The Ming renovated the old Qin and Han walls and extended them. The Ming wall stretched some 4,500 miles from the Korean border at Dandong to the city of Jayuguan in the western desert. Today that fort is one of the most impressive, ornate, and sophisticated military constructions in the history of China.

The Ming Dynasty came into power in 1368 inheriting a nation crushed by 100 years of rule by the Mongols. The mighty Genghis Khan had united these tribes in 1206 and had pushed their way through China. Ultimately they fell from within. A peasant revolt spelled the defeat of the Mongol empire. The leader of this revolt was Zhu Yangzhong who was installed as the first Ming Emperor. He immediately took up the challenge to begin building the great defense again. The enthusiasm in which the Ming emperors embraced this ambition was staggering. They built more wall than any other dynasty. The Ming wall was typically built with a stone facing over tamped inner clay. This wall was almost indestructible.

The Ming bricks were a marvel of engineering holding up to a pressure of over 1000 pounds per square inch. The mortar was of super strength. The mortar was stronger than the bricks themselves. The puzzle of this super strength has now been solved. The mystery ingredient was rice flour. With innovations like these, the Ming was able to build spectacular monuments. A feature of the wall was water drainage systems that channeled the water to the Chinese side and withheld the water to the enemy side and thus inhibited plant growth and so denied cover to the attackers.

Warning towers were built in enemy territory. These spurs were built out from the main wall and permitted the Chinese to attack the marauders from two sides. The armies were controlled from watchtowers that were built every 200 yards along the Ming walls. Locks and bolts secured the doors and windows from within creating a formidable fortress. From these towers the defenders could unleash arrows and spears from heavily protected slits. Later cannon were used. Having discovered gunpowder, the Ming was also the first to use hand grenades and mines. Stones were also pushed through special openings to create manmade avalanches to crush the enemy. If the attackers succeeded in scaling the wall, the defenders could retreat to the guard towers. These guard towers were only accessible by retractable ladders.