The Legend of Co Loa Citadel

Co Loa Citadel

Located 18 km north of Hanoi, Co Loa Citadel was the capital of the Au Lac kingdom in the 3rd century B.C., under Thuc Phan – An Duong Vuong. Its spiral layout (Loa thanh) combined concentric ramparts and flooded moats to slow down the enemy. Today, three earthen ramparts remain: Thanh Ngoai (~8 km), Thanh Giua (polygon, ~6.5 km), and Thanh Trong (rectangle, ~1.6 km). The embankments reach 12 meters, with staggered and reduced gates that impose winding access – a remarkable defensive device in Southeast Asia.

My Chau’s escape on An Duong Vuong’s horse; the shadow of Trong Thuy looms in the distance

Beyond engineering, Co Loa is a place of memory and myths: the legend of Kim Quy’s crossbow (the “magic” crossbow), the tragic love story of My Chau – Trong Thuy, and tales of protective spirits aiding in the building of the ramparts. A popular variant recounts that a goblin rooster metamorphosed into a six-legged owl holding a magic letter; the Golden Turtle (Kim Quy), transformed into a mouse, bit its leg to make it drop the letter – thus breaking the curse and allowing the king to complete the citadel “in two weeks” (according to legend).

The visiting route includes the dinh (communal house, “Ngu trieu di quy” panel), the Am Ba Chua dedicated to My Chau, the Den Thuong (temple of An Duong Vuong), and the Gieng Ngoc (“jade well”), where Trong Thuy reportedly took his life; it is said that rinsing pearls in this water makes them shine brighter.

Temple of An Duong Vuong

Classified as a national historic and cultural site since 1962, Co Loa has yielded a rich archaeological harvest: thousands of bronze arrowheads, agricultural tools, ceramics, and trong dong (bronze drums), testimony to an advanced material culture. In the 10th century, under Ngo Quyen, the site briefly regained its role as capital, confirming its strategic value. Between unique military architecture, founding legends, and living rituals (festival on the 6th day of the 1st lunar month, with eight villages in procession), Co Loa is a privileged gateway into Vietnamese antiquity – ideal for a half-day excursion from Hanoi.