Located in the heart of Son Tay town, about 40km from Hanoi's center, Son Tay citadel has an ancient military architecture, built in the reign of King Minh Mang (1822).
Thanks for its strategic location on the Red River, Son Tay citadel was an important military outpost, especially against invasions from the north.
The flag pillar today
The flag pillar that was built in 1884
The square fort with a length of 450 meters is now in the heart of the city, about two miles from the Red River.
It was completely surrounded by a five meter wall with loopholes and a three-meter deep and 20 meter wide moat. On each side, there was a gate, guarded by cannons, which was reached via a stone bridge. 
The four main ports: The south gate called Tien gate; the north gate is called Hau, the East and the West gates. The North gate and the adjacent walls were restored some time ago. The West and the South Gate have also been preserved, while the gate in the East was destroyed. 
The entrance to the fortress is possible only through the North or the South Gate.
Hundred-year-old trees cover the mossy citadel walls and gates.
Each port on the top, there is guard floor with only one entrance.
Son Tay Ancient Citadel has become a unique military architectural work and cultural historical relic, attracting many tourists. 
Paying a visit to Son Tay, tourists can connect well with a journey into the past to the community of Duong Lam which is quite close to the town.
Photo: the flag tower which was built in 1844
Flag tower and incense burner
The bridge to the northern gate today
The northern gate
The watch tower
The moat around the citadel
A romantic beauty
A peaceful lane
Kinh Thien palace
Compiled by Pha Le
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