The Great Wall Was Built with Arsenic

The Great Wall of China contains a hidden secret that helped it survive for millennia. Builders added arsenic to the wall's materials, earning it the nickname the poison of kings. This toxic element served a practical purpose: it deterred insects, plants, and other organisms that might otherwise have eroded the structure. The arsenic made the wall inhospitable to life, preventing biological decay. This preservation technique was remarkably effective, allowing sections of the wall to survive for over 2,000 years. However, it also means that visitors should avoid touching or climbing unrestored sections of the wall, as the arsenic could still pose health risks. The use of arsenic demonstrates the sophisticated engineering knowledge of ancient Chinese builders.