Quin Shi Huang’s Tomb, China
The first Emperor of China who ended the Warring States period and brought the mighty nation together took one fascinating secret to his grave: his grave. The tomb of Quin Shi Huang is one of the most priceless historical relics of all time, but it has never been excavated. Historical records describe a massive underground complex the size of a city, populated with thousands of life-size terracotta statues of soldiers and concubines. A number of those statues have been dug up and exhibited around the world, but the central tomb chamber remains inviolate. One reason is that rivers of incredibly toxic mercury, which could release severe poisons into the soil and groundwater if not handled correctly, reportedly surround the burial area.