Changsha is a mysterious and miraculous city in China with many unbelievable but true records, sites and archaeological discoveries. Have you ever seen a piece of the lightest silk garment throughout the world with the weight of 49 grams and the length of 1.23 meters, which we can't reproduce by the most advanced modern technology? Does it mean the techniques and science in the past have surpassed the accomplishment human have reached at present? It is incogitable!...