The An Duong Vuong Temple Festival is a traditional festival that honors King An Duong Vuong, who built the Co Loa Citadel and ruled over the ancient kingdom of Au Lac. The festival is held on the 6th day of the first lunar month every year in Co Loa village, Dong Anh district, Hanoi, which is about 17 km from the center of Hanoi.

The festival begins with a procession of the 12 hamlets of Co Loa village, who march to the temple of the King with their palanquins and offerings. The procession is led by an ancient music band, followed by the elders of the village and the royal palanquin of the King.

The main ceremony takes place at the Thuong Temple, where the King’s statue and relics are kept. The temple is decorated with five-colour flags, pink and white horses, and incense tables. The offerings include a glass box containing a pair of mandarin’s boots and the King’s weapons. The King’s hat, called “mũ bình thiên”, is hidden inside the altar. After the ceremony, the procession circles around the Trong Thuy well, where the tragic love story of Princess My Chau and Prince Trong Thuy took place. Then they return to the Ngu Trieu communal house, where only the palanquin of Co Loa is kept.