S?n Tây Citadel was built by King Minh M?ng in 1822 to defend the western gateway to the city of Th?ng Long (Hà N?i). Constructed mainly from laterite, the four-sided citadel featured a 1,303 metre perimeter with a 4.4 metre high wall, surrounded by a 20 metre wide moat. The foundations of various buildings may still be seen within the complex. The structure was almost completely destroyed by the French in 1883, leaving only the north and south gates standing. While the north gate has been restored unsympathetically using concrete, the south gate remains almost intact.

Each corner of the citadel was armed with cannon. Furthermore, there is the Kinh Thien Palace - the rest house of the king, residences and offices of provincial leaders, warehouses, and troop camps. Due to time and the effects of war, parts of the ancient wall were destroyed. Measures to prevent and restore this historical relic have recently been implemented.