The Great Wall Of China - Unbelievable Secrets & Unknown Facts This video takes you to a ride full of unbelievable secrets and unknown facts about "The Great Wall Of China" First, there’s not just one wall, but many. The Great "Walls" of China, at least 16 of them, built over 2,400 years by successive emperors and dynasties. Total length: 21,000 km, three times longer than previously thought, longer than the distance between the poles. The idea was the same as Hadrian’s, though: to keep out uncouth marauding neighbours from the north: Scots, Mongols, they’re much of a muchness. Here are some, reconstructed Mongols, galloping thunderingly on horseback and firing their bows. Ooch aye the noo, Genghis, good arrers. So how did they come up with the new figures? Technology, that’s how: aerial mapping, satellite images, 3D models, GPS, laser scanning. And drones. The helicopter drone has become an essential piece of kit in the making of television documentaries like this; they breathe new life into the very ancient, using the very modern. These drones are good. They’re got five cameras and loads of mapping stuff – you can just fly them along the wall and they come back with everything you need to know about it. Also required is a lot of martial music and a script full of drama and superlatives. It is “THE MOST EXTRAORDINARY feat of engineering in history”; “one of the MOST ICONIC man-made structures on the planet”; they’re using “GROUNDBREAKING science” and “CUTTING EDGE chemistry” to uncover the enigma at the heart of the WORLD’S GREATEST MEGASTRUCTURE”. Always good to get a megastructure, a mega-something, anyway, in there. Basically it’s awesome. If the Great Wall(s) of China was a creature that swam in the sea in would be a great white shark, an APEX PREDATOR. I could do with less hyperbole. It doesn’t need it; it’s interesting enough in its own right. What else have they discovered, then, using all their groundbreaking science, technology and code-breaking? That they had a complex signalling system, early Chinese semaphore, to warn of attack. A red flag up the pole meant 50 Xiongnu coming. Three red flags? 200 Xiongnu coming. Big bonfire? 1,000 Xiongnu coming, etc. Xiongnu were terrifying early raiders – early Scots, basically. Big bonfire, squeaky bum time, in other words. My favourite thing about the wall, and about the programme, comes from the CUTTING EDGE science. Top chemistry professor and expert in ancient building materials Dr Xiang has taken samples from the Ming dynasty wall, which was built after the Mongols – who had occupied China for over a century – were finally sent packing. He has found that the secret of the Ming wall’s strength and longevity lies not in the bricks but in the mortar. The whitish colour of the mortar was said, in legend, to be because it was made from ground-up human bones. Not so, says Xiang. The secret ingredient that went into the mortar, kept the WORLD’S GREATEST MEGASTRUCTURE standing for hundreds of years? Sticky rice. Isn’t that great? Take note, modern brickies: a sprinkle of rice in the mortar and it’ll last for ever; Ben’s your uncle.

• published: 14 Dec 2014
• views: 152