National Geographic China's Ghost Army: Is every warrior's face different? How were 8,000 made in eleven years, when every one should have taken a month? Why does every warrior have a name hidden on their body? Could they originally have been brightly coloured? And how big must their firing kilns have been? There are still plenty of unanswered questions about Shihuangdi's Terracotta Army. Using face recognition technology, painstaking archaeological research and interviews with craftsmen who build life-size replicas today, experts unravel the mysteries of the two-metre tall, 300kg pottery figurines found 37 years ago in the tomb of China's first Qin Dynasty ruler, revealing why they were one of the most fascinating, and mysterious, finds of the last century.