Located on a 900-sq.m site in An Nhon township, the citadel was built by King Thai Duc in the late 18th century on a foundation dating from the Champa Kingdom. Several stone walls and granite-tiled roads remain intact. 

The citadel is the only architecture from the Tay Son dynasty remaining that has further potential for archaeological exploration. 

A two-month preliminary excavation has been implemented by archaeologists from the Vietnam Archeology Institute in cooperation with provincial authorities.