XI'AN - Archaeologists said a 4-square-kilometer city ruins discovered in Northwest China's Shaanxi province was the largest of its kind in neolithic China.

The conclusion came after more than 40 archaeologists researched into the 4,000-year-old Shimao Ruins in Shenmu county and measured the exact size of the ancient stone city.

"The city has magnificent stone walls and we've unearthed a large number of carved jade, which hint at the city' core status in north China's early civilization," said Zhang Zhongpei, head of Archaeological Society of China.

Shimao Ruins was first found in 1976 in the form of a small town, but local archaeological authorities conducted a thorough survey last year, which led to the discovery of more city walls.

The city was found to have inner and outer structures, and the walls surrounding the outer city extended over an area of 4.25 square kilometers.

Other findings from the site included a piece of mural, which archaeologists believe was the oldest in China.