Located 36 kilometres east of Xi'an, capital of Northwest China's Shaanxi Province, the grand mausoleum was the eternal resting place for Ying Zheng, the first emperor of the Qin Dynasty (221-206 BC), who unified China for the first time.

According to historical records, it took 700,000 people 36 years to build the luxurious underground tomb, where mercury was used to imitate rivers and lakes, numerous treasures and women were buried with the dead emperor.

However, the actual structure and position of the mausoleum are still a mystery despite several surveys having been conducted since the 1970s.

Now, scientists and archaeologists are carrying out a large-scale investigation of the tomb to get a general picture of it, said Guan Haiyan, director of the Shaanxi Remote Sensing Centre.

"We will use aerial remote sensing and geophysical techniques to identify the position, depth and basic structure of the underground palace, as well as the 60-square-kilometre area surrounding the tomb," said Guan, who is also the project's senior engineer.

The survey, listed as a key project of the National High Technology Research and Development Programme, is by far the most comprehensive research ever on the mausoleum. Work is due to be finished by September next year.

"At that time, people can tell whether or not there were mercurial rivers and lakes underground and whether the historical records told the truth," said Guan.

So far, only three vaults containing thousands of terracotta figures (known as bing ma yong) have been found 1.5 kilometers east of the mausoleum, and two sets of large bronze chariots and horses were excavated west of the mausoleum.

Discovery of the buried legion has aroused great interest all over the world, making it "the eighth wonder of the world." However, this is just the tip of the iceberg.

As opposed to the Egyptian pyramids, which were constructed above ground level, the mausoleum is a huge underground complex designed to mirror the street plan of the Qin Dynasty's capital. It is the first and the largest imperial mausoleum in China.

Tens of thousands of statues and treasures undoubtedly still remain to be unearthed from the site, and they will be extremely valuable to study the Qin Dynasty's society, archaeologists say.

In December 1987, the United Nations Educational, Scientific and Cultural Organization listed the mausoleum as a World Heritage Site, together with the Great Wall and the Imperial Palace of the Ming and Qing dynasties (1368-1911).

(China Daily December 13, 2002)