Cổ Loa Citadel is a citadel built near Phong Khe, about 20km to the North of today’s Hanoi, during the end of the Hồng Bàng Dynasty (about 257 BCE). The fortress is a spiral-shaped complex of the then new capital. Its name is derived from the Sino-Vietnamese meaning "old spiral." The site has been the source of various relics of the Dong Son culture of the Bronze Age
