The architectural wonder constructed by the Ming Dynasty to protect against invasions is the Great Wall of China. While portions of the wall were built earlier, significant expansions and fortifications took place during the Ming Dynasty (1368-1644). This extensive fortification system was primarily constructed to defend against invasions from nomadic groups, particularly the Mongols. The Great Wall stretches thousands of miles, incorporating watchtowers and fortresses for military defense. Beyond its military purpose, the wall has become a symbol of Chinese strength and perseverance and represents the incredible feats of engineering and labor during the Ming era.