Farmers near Xi'an, China were digging a well in March 1974 when their shovels hit a buried clay head. It led to the Terracotta Army: an estimated 8,000 soldiers, of which only 2,000 have been dug up so far. They guard the 2,200-year-old tomb of China's first emperor, a tomb that has never been opened. Ancient writers said it holds rivers of mercury, and soil tests found the mercury is real.
