Terra-cotta Warriors of Xian, China

The original structure that housed the terra-cotta army was a 7,000-square-yard roof of pine logs positioned atop mounds of earth. Notice the indentions in the dirt mounds on either side of the trenches. Straw matting and clay was placed on top of these logs to preserve the army. After the completion of the burial complex, invading armies broke into the chamber and sacked the site. They took most of the weapons each of the terra-cotta soldiers possessed, most notably the spears and automatic crossbows. They smashed many of the soldiers and set fire to the complex. In later years the weakened roof collapsed, crushing many more of the hollow clay figurines. The loess soils of this area of China covered over the tomb, setting the stage for the discovery 2,200 years later.