The An Tho citadel in An Dan commune, Tuy An district, served as the headquarters of the provincial feudal authority under the Nguyen Dynasty from early 19th to early 20th centuries.

Being much more ancient, the Ho citadel was a political, cultural and social centre of the Cham people from the 5th to 7th centuries. The 1 sq. km citadel in Hoa Dinh Dong commune, Phu Hoa district, remains almost intact with typical Cham architecture.

In the Ho citadel, thousands of valuable Cham ceramic objects were unearthed in 2003 and 2004 by scientists from the Vietnam Archaeology Institute.