Though excavations have been slowly uncovering the area over the last 30 years, but the underground palace, the central part of the mausoleum remains a mystery. Archaeologists predict that might take 200 years to unearth it all, and no one is quite sure what they'll find-the artisans and craftsmen who built it were rumored to have been entombed inside to ensure they never revealed the emperor's secrets.

In a vault of approximately 12,000m2 and 5m underground lay some 8,000 terracotta infantry soldiers, archers, cavalrymen and chariots arranged in battle formation, ready to defend their emperor's immortal soul. Each soldier is approximately 1.8m-tall, with higher-ranking soldier being taller, and made of 7.6cm thick terracotta clay. Each part of the hollow body was made separately, while the trunk, limbs and hands were mass-produced, the heads were individually constructed and the face of each warrior is distinct. The terracotta sculptures show a high level of artistry with individualized facial expressions, hairstyles and clothing and were once brightly painted with black armor, colorful red scarves and green pants, though the colors have long faded. As warriors, they each held weapon, bronze swords, spears, axes and halberds-which were still sharp when discovered, and longbows and crossbows.

Chinese scientists have finally solved a lengthy riddle of where the 8,000 terracotta warriors were made that were unearthed in the 1970s from the tomb of Qin Shihuang, the first emperor who unified China. After 3-year joint research project, scientists reached the conclusion that the world-renowned terracotta warriors were created close to where they were excavated. The purpose of making these warriors and horses was to sustain and protect the spirit of their ruler for all the time.