Construction of the Great Wall (Qin Dynasty), c. 221–206 BCE

Emperor Qin Shi Huang ordered linking and expansion of earlier walls into a continuous barrier stretching over 5,000 km to deter nomadic incursions. Forced labor, harsh conditions, and mountainous terrain made construction brutal, yet its legacy endures as emblem of imperial power.
New Idea: Could archaeological surveys of hidden watchtowers reveal insights into ancient supply lines and the daily lives of conscripted workers?