Cổ Loa Citadel

Cổ Loa Citadel (Vietnamese: Thành Cổ Loa) is an important fortified settlement and archaeological site in present-day Hanoi's Đông Anh district, roughly 17 kilometers north of present-day Hanoi, in the upper plain north of the Red River.

[3] The settlement’s concentric walls resemble a snail’s shell; it had an outer embankment covering 600 hectares.

[2] The mythical story goes that when the fortress was being built, all the work done during the day was mysteriously destroyed at night.

The moats consist of a series of streams, including the Hoàng Giang River and a network of lakes that provided Cổ Loa with protection and navigation.

And it was suggested that this rampart was constructed by a local and indigenous society prior to the colonization of Han dynasty.

[7] The stamped earth technique or Hangtu method associated with ancient China may have been used in Cổ Loa, but studies of the defensive works are still in a preliminary stage.

Also, archaeologists have estimated that over two million cubic metres of material were moved in order to construct the entire fortress, including moats that were fed by the Hoàng River.

Various Cổ Loa artefacts represented "elite-level or royal characteristics", discovered only within the site’s enclosures, supporting the notion of centralised production and monopolisation.

The rarity of such objects in Southeast Asia and the range found at Cổ Loa is believed to possibly be unique.

One spearhead generated special interest because it was bimetallic, with an iron blade fitting into a bronze socket.