China has approved a plan to preserve key parts of the Great Wall of Qi in eastern Shandong Province, a world heritage site and the predecessor of the more famous Great Wall in northern China, officials said on Thursday. Built between 770 BCE and 476 BCE in the ancient state of Qi, or Today's Shandong, the Great Wall of Qi is the oldest Great Wall in China.It started at a small village in what is now Changqing County, with passes, gates, castles and beacon towers along a total length of 620 kilometers till it met the sea near Qingdao. Due to natural erosion, construction, mining and land reclamation, the Great Wall of Qi is in a worsening condition, said Xie Zhixiu, deputy head of Shandong cultural heritage department. The plan drawn by Shandong authorities and approved by the central government gives priority to the preservation of 10 key sections and heritage sites and involves reinforcement of seriously damaged sections, removal of vegetation and improvements to drainage. As military defense projects, more than 20 emperors in ancient China ordered the building or renovation of walls and fortifications. The Great Wall of China was inscribed on the world cultural heritage list in 1987, the Great Wall of Qi is part of this cultural heritage.