Based on the ancient practice of geomancy, the Citadel was designed and planned around the natural elements in the area north of the Perfume river. The complex faces southeast, taking Mount Ngu Binh (Royal Screen Mount) as a natural screen. Two islets in the Perfume river, Ta Thanh Long (Left Green Dragon) and Huu Bach Ho (Right White Tiger) play the role of sentinels for the Citadel. The construction of the Citadel took place from 1805 to 1832. The Citadel is a square enclosure with a circumference of 10,000 m, a height of 6.6 m and a thickness of about 21 cm. The center of the wall is packed with dirt while the outer shell is built with bricks.
here are ten gates to access the Citadel each with a two story watch tower. The gates are named according to their direction of exit. The southeastern gate is also known as Thuong Tu gate, The Eastern gate is also called Cua Dong Ba etc...The Citadel was built to accommodate 24 bastions with over 400 canons.
