In Son Tay Town, Ha Tay Province, about 40km from Hanoi City, body of the wall was built of hard sandstone with one gate on each side.
Son Tay Citadel was built by King Minh Mang in 1822 to defend the western gateway to the city of Thang Long (Hanoi). 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. Son Tay Citadel has the style of a Vauban fortification and in time French architects praised it as a masterpiece of Vietnamese architecture. The citadel 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 by using concrete, the south gate remains almost intact.
Each corner of Son Tay 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.
Son Tay ancient citadel is coved by green trees. There is the moat that surrounds ancient citadel. It’s really quiet and cool for walking.
Son Tay Citadel should be one of the great symbols of Vietnam’s cultural heritage together along with Co Loa ancient citadel, Hanoi citadel and Hue Imperial palace.