UNKNOWN CHINA | Natural Wonders and Megaprojects

China, an immense stage filled with nature's wonders. Time has shaped hidden marvels that seem impossible. Human ingenuity reaches the most remote corners. Structures rise to meet every challenge. And what seems like barriers become opportunities. [Music] Today we set off on a breathtaking journey through places in China that feel unreal. We'll reach the most difficult corners to access. Shiaojai Tiangong [Music] located in Chongqing. It's considered the largest and deepest natural sinkhole in the world. So vast it has its own ecosystem. [Music] From above it looks like a giant crater surrounded by lush green forests. [Music] Inside lies a microclimate with high humidity, limited sunlight, and rare species of flora and fauna. Descending feels like stepping into a lost world that has remained untouched for millennia. Despite some sunlight reaching in, the bottom stays mostly dim, allowing life forms adapted to darkness to thrive. [Music] Gerine Cave located in Gujo Province. This colossal cave boasts extraordinary geological formations. Known as the most spectacular cave in Asia, it was accidentally discovered by a group of local explorers in 1980. It has expanded without destructive geological events for over 2 million years, explaining its current massive size. The cave features 12 km or 7.45 mi of explored passageways and reaches a height of 150 m or 492 ft, the equivalent of a 40story building. Inside are strange geological structures like gypsum flowers, twisted columns, and stone veils. [Music] Near the entrance and in lit areas, mosses, ferns, and lychans thrive in the cave's constant humidity. Atalier stairs. This metal staircase with thousands of steps connects the remote village of Adelier to the outside world. [Music] It climbs a sheer cliff face with a vertical drop of 800 m or 2,624 ft. [Music] Striking images of children climbing rope ladders sparked the start of construction in 2016. In just 3 months, the local government completed the project, overcoming the altitude and difficult terrain. The stairs are dizzying. Some sections climb at a 70° angle. [Music] Adelier sits at the top, perched on the edge of a cliff that plunges 1,000 m or 3,280 ft into the valley below. In the past, these cliffs acted as natural barriers, shielding the community from invaders and looters. [Music] Moreover, the mountain slopes offered fertile terrace soil ideal for growing corn, potatoes, and other crops.