The Great Wall of Qi is the oldest existing Great Wall

Great Wall of China

The Great Wall of China is a series of stone and earthen fortifications in northern China, built originally to protect the northern borders of the Chinese Empire against intrusions by various nomadic groups...

 in China

China

Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

. Construction of the wall started in 685 BCE (during the Spring and Autumn Period) by the state of Qi, to defend itself against an invasion by the Kingdom of Chu. The existing sections date back to 500 BCE. Construction ended during the Warring States Period

Warring States Period

The Warring States Period , also known as the Era of Warring States, or the Warring Kingdoms period, covers the Iron Age period from about 475 BC to the reunification of China under the Qin Dynasty in 221 BC...

. The wall stretches from the areas under the administration of the present-day city of Jinan

Jinan

Jinan is the capital of Shandong province in Eastern China. The area of present-day Jinan has played an important role in the history of the region from the earliest beginnings of civilisation and has evolved into a major national administrative, economic, and transportation hub...

 to the present-day city of Qingdao

Qingdao

' also known in the West by its postal map spelling Tsingtao, is a major city with a population of over 8.715 million in eastern Shandong province, Eastern China. Its built up area, made of 7 urban districts plus Jimo city, is home to about 4,346,000 inhabitants in 2010.It borders Yantai to the...

 across the present-day cities of Tai'an

Tai'an

Tai'an is a prefecture-level city in western Shandong province, People's Republic of China.Centered around Mount Tai, the city borders the provincial capital of Jinan to the north, Laiwu to the northeast, Zibo to the east, Linyi to the southeast, Liaocheng to the extreme west and Jining to the south...

, Zibo

Zibo

Zibo is a prefecture-level city in central Shandong province, People's Republic of China. It borders the provincial capital of Jinan to the west, Laiwu and Tai'an to the southwest, Linyi to the south, Weifang to the east, Dongying to the northeast, and Binzhou the north.Located in the middle part...

, Laiwu

Laiwu

Laiwu is a prefecture-level city in central Shandong Province, People's Republic of China. The smallest prefecture-level city in the province, it borders the provincial capital of Jinan to the north, Zibo to the east and Tai'an to the southwest....

, Weifang

Weifang

Weifang is a prefecture-level city in central Shandong province, People's Republic of China. It borders Dongying to the northwest, Zibo to the west, Linyi to the southwest, Rizhao to the south, Qingdao to the east, and looks out to the Laizhou Bay to the north.-History:Weifang is a historical city...

, Linyi

Linyi

Linyi is a prefecture-level city in the south of Shandong province, People's Republic of China. The largest prefecture-level city in Shandong both by area and total population, Linyi borders Rizhao to the east, Weifang to the northeast, Zibo to the north, Tai'an to the northwest, Jining to the...

, and Rizhao

Rizhao

Rizhao is a prefecture-level city in southeastern Shandong province, People's Republic of China. It is situated on the coastline along the Yellow Sea, borders Qingdao to the northeast, Weifang to the north, Linyi to the west and southwest, and faces Korea and Japan across the Yellow Sea to the east...

. Its total length has been estimated at about 600 kilometers.