The tomb of China's first emperor, guarded for more than 2000 years by 8000 terracotta warriors and horses, has yielded another archaeological secret.

Archaeologists have confirmed that a 30m-high building is buried in the vast mausoleum of Emperor Qinshihuang near the former capital, Xian.

Duan Qingbo, a researcher with Shaanxi Institute of Archaeology, said the building might have been constructed for the soul of the emperor to depart.

Archaeologists have been using remote sensing technology since 2002 to study the internal structure of the unexcavated mausoleum.