Taking place from the 6th to the 16th day of the Lunar New Year at An Duong Vuong temple in Dong Anh District, on the outskirts of Hanoi, Co Loa Festival based on the legend of An Duong King of Au Lac and his magic crossbow. According to the legend, Genius Kim Quy, a Golden Tortoise, gave Thuc Phan (An Duong Vuong) a magic crossbow which could kill tens of thousands of enemy soldiers at a shot. However, the King’s daughter My Chau told the secret of her father's magic crossbow to her husband Trong Thuy, the son of rebel Chinese general Trieu Da, and thereby unwittingly enabled Trieu Da to conquer Co Loa in 208 B.C. Learned of the reason for his defeat, King An Duong is said to have killed his daughter and then committed suicide. Nowadays, in Co Loa citadel, there exists many vestiges still reminding you of the episodes of the legend.

Visiting Co Loa on the 6th of the 1st lunar month, you will have the opportunity to take part in Co Loa Festival organized by the 12 hamlets of the village. Thuc Phan An Duong Vuong was remembered for building Co Loa citadel and for ruling Au Lac for 50 years, 3rd century B.C. Besides the ceremonial rites in honour of King An Duong Vuong at the Upper Temple, there is an imposing and solemn procession of 12 palankeens going round the Trong Thuy Well to the Village gate. Moreover, in the festival, people also put a lot of effort into celebrating traditional activities.

On the afternoon of the 5th day of the first lunar month, all of the eight communes (including Co Loa Commune and the establishing relations between seven communes) hold the incense offering ceremony at the communal house. At Thuong Temple, village officials and mandarins hold the similar ceremony and revise the King’s contributions and achievements. The official festival day, which is on the 6th of the first lunar month, commences with processions of notables from surrounding villages to the King An Duong Temple where a miniature royal court containing an incense burner, a stone tablet and a funeral oration is placed in front of the two altars. The literature procession is preceded by a flag that symbolizes the five elements (metal, wood, water, fire and earth), a musical company, and a sacrifice. This procession featuring two sedan chairs proceeds through the 12 hamlets of Co Loa Commune. One carries a small statue of the King, the other a beheaded statue of his daughter which symbolizes for her punishment. The procession then continues to the Trong Thuy Well and back to the various hamlets, accompanied by firecrackers.

Preceded by the literature procession is a sacrificial ceremony that lasts until 12 p.m. The ceremony takes place in the King's honour, accompanied by traditional music. Next to the ceremony is the procession of 12 villages to take the god from the temple to the communal house so that he can watch the festivities. This is the biggest procession with the participation of all the palanquins. When reaching the main entrance, the palanquins return to their villages. Co Loa’s procession and palanquin do the same rituals once more at the communal house. The festival continues until the 16th day of the first lunar month, with evening fireworks displays, traditional games such as cock fighting, human chess, tug of war, card playing, wrestling, swing, rope climbing, martial arts, flag dancing and archery and performances of ca tru, cheo and tuong.

On the final day of the festival, a grand farewell ceremony will be held at the temple. After the rituals which are the same as in the main festival day, the cult table of god will be returned to the sanctuary. Local people enjoy the god’s favor and expect a year of prosperity and protection from the god. The meaningful festival is always closed with a thanksgiving ceremony.