Covered by a wheat field and a peach tree orchard, the 1,000-year-old graveyard had belonged to a noble's family during China's Northern Song Dynasty (960-1127). Archaeologists found it the same way they had found countless others: they followed in the steps of grave robbers.

One of the tombs was buried extra deep and had a special design, and it quickly aroused the archaeologists' curiosity. But at that point, they had no idea they had just discovered the tomb of Lu Dalin, the ancient bronze ware expert considered the father of Chinese archaeology.

The discovery of the Lu family's 1,000-year-old graveyard in Wulitou Village, Lantian County, in northwest China's Shaanxi Province, has been selected by the Chinese Academy of Social Sciences' Institute of Archaeology as one of the six most important archaeological discoveries in China in 2009.

Archaeologists excavated 29 of the graveyards' tombs between March 2006 and December 2009, covering an area of 88,000 square meters. But they knew it was tomb M2 that was special.

When they had dug 3.6 meters down, they discovered the burial chamber. But they were puzzled to find there was no coffin, bones or funeral objects in the chamber. They continued digging down and found another burial chamber at a depth of 10.7 meters directly under the first one. But it, too, was empty.

It wasn't until they had dug down 12.5 meters that they found the third chamber with a decayed coffin inside. But the bones in the coffin already appeared disturbed.

"It was the first time I had seen a tomb like this. I guess it was designed that way to prevent burglary," said Zhang Yun, a leading archaeologist with Shaanxi Province's Institute of Archaeology.

"Obviously, those who built the tomb made a great effort to prevent robbery. For instance, they made the entrance to the tomb passage very small, so that it was hard to find from the surface. And the real chamber lay under a layer of gravel, which made it especially difficult to find," Zhang added.