SHIJIAZHUANG, June 6 (Xinhua) -- The principle of minimum intervention was highlighted at a forum on the protection and restoration of the Great Wall Tuesday.

Chai Xiaoming, head of the Chinese Academy of Cultural Heritage, called for ensuring the principle replaced bad practice, at the forum in Qinhuangdao, north China's Hebei Province.

Chai warned that too much restoration would damage preservation.

Song Xinchao, deputy head of the State Administration of Cultural Heritage, also urged preventative protection.

The Great Wall, a symbol of China, is actually not just one wall, but many interconnected walls built between the third century B.C. and the Ming Dynasty (1368-1644).

The existing sections are mainly the Ming wall, which stretches over 8,800 kilometers. It was listed as a World Heritage Site by UNESCO in 1987.