The structure that served as a famous fortification in ancient China is the Great Wall of China. Construction of the wall began as early as the 7th century BC and continued in various forms until the 17th century. It was built primarily to protect against invasions by nomadic tribes from the north and to control trade along the Silk Road. Stretching thousands of miles across northern China, the Great Wall is an iconic symbol of Chinese strength and perseverance, showcasing ancient engineering skills and serving as a significant cultural heritage site today.