This is one of the five projects under the Municipal People’s Committee’s plan to improve the environment of lakes in the inner city to mark Hanoi’s 1,000th founding anniversary. The project is expected to be completed within four months.

Located in Son Tay Town, 42km from central Hanoi, the Son Tay Ancient Citadel was built in 1822 under the reign of King Minh Mang to defend the western gateway of the city of Thang Long, which is now Hanoi. Its walls were made of laterite, an extremely strong type of stone.

Covering an area of 20ha, the square-shaped citadel is surrounded by a 20m-wide, 2,000m-long moat. It has four gates, namely the Front (Tien), the Back (Hau), the Right (Huu) and the Left (Ta).

Inside the citadel, there are an 18m-high flagpole, a ceremonial place called Kinh Thien Hall, a lotus pond, a water well and soldiers’ camps.

During the 1870-1980s, the citadel was the Nguyen Royal Court’s defence centre during the resistance war against French colonialism.

Time and war have destroyed many areas inside the unique military fortification, which was recognised by the State as a national historical and architectural relic in 1994. In February 2009, the Hanoi People’s Committee decided to preserve and restore the Son Tay Ancient Citadel to serve the millennium celebration of Thang Long-Hanoi.

Together with the moat, several other sections in the citadel such as the flagpole, water well and Vong Cung - a place for the King and mandarins to relax and offer scarifies – have also been restored and upgraded.