The Great Wall of China was originally built for defensive purposes, primarily to protect Chinese states and empires from invasions by nomadic tribes from the north. Construction began in the 7th century BC, and it evolved over centuries, with various dynasties expanding and reinforcing the structure. The wall served as a military fortification, controlling immigration and trade along the Silk Road, and allowing for better surveillance of enemies. Today, the Great Wall stands as a symbol of China's historical strength and determination, attracting millions of visitors each year.