A place believed to have been the capital of Vietnam's legendary Au Lac dynasty, c 258-207 BC. It is about 20 km northwest of Hanoi and there are three walls which surrounded the city in a spiral. In AD 939 the kingdom of Nam Viet centered in the Red River valley at Co Loa. Ngo Quyen drove the Chinese out of the area and founded his own dynasty, which endured only until 954. Historical sites include the Co Loa citadel.