From sticky rice mortar in the Great Wall to a mercury-guarded tomb, we unpack China's most ingenious ancient engineering. Plus, the ice roads that built the Forbidden City. In this Mysterious Earth episode, we investigate three icons of ancient China through their most puzzling secrets. First, the Great Wall: more than a single barrier, it is a vast network of fences, towers, fortresses and passes. An archaeological survey published by Xinhua in 2012 set its total length at 13,170 miles (21,196 km). In 2015, researcher Zhu Xinhua led a team that uncovered nine previously unknown sections totaling 6.2 miles in Gansu, supporting theories that early construction aimed to block crossings of the Yellow River. We also examine the Wall’s most unlikely ingredient: a mortar made by mixing powdered limestone with sticky rice soup, one of the earliest large-scale inorganic-organic composites. With more than 10 million visitors a year, can this ancient structure endure modern tourism? Next, we revisit the 1974 discovery in Shanxi, where farmers digging for water found fragments that led archaeologists to a life-sized army of terracotta warriors guarding the tomb of China’s first emperor. Over 2,000 figures have been excavated, with satellite imagery suggesting around 8,000 in total. Each soldier is unique, and over 40,000 arrows and other bronze weapons have been recovered. Why is the mausoleum still sealed? Ancient texts warn of a river of mercury, and tests around the site show unusually high mercury levels. Remote sensing has revealed a buried chamber, but the tomb remains closed until technology can protect its fragile contents. Finally, we track the intrigue behind Beijing’s Forbidden City. After Zhu Di overthrew his nephew, he moved the capital north and, from 1406 to 1420, built a 980-building fortress shaped by feng shui and rigid court ritual. A 2013 translation by engineer Jiang Li revealed how massive stones were hauled from quarries: workers slid blocks, some over 100 tons, on sledges along wet ice, digging wells every 500 meters to flood the path. Calculations show 46 men could move a 100-ton stone at roughly three inches per second, taking about 28 days per piece. From sticky rice to ice roads and a tomb that defies entry, this episode explores how power, belief and engineering shaped ancient China. #GreatWallOfChina #TerracottaArmy #ForbiddenCity #AncientChina #Archaeology #History #Engineering #MysteriousEarth