Hue citadel, built in 1803 and taken nearly 30 years to complete, is a 9000m in circumference rampart parade with 24 fortresses on the surface. Outside, along the edge, there is a deep trench used for protection. The citadel has 8 gates that face to 8 directions: North, West, South, East, Northwest, Southwest, Northeast, and Southeast. According to principles of Oriental feng shui, the citadel faces to the South, 4 sides is surrounded by rivers system. Inside the citadel is the Royal palace, includes the Royal citadel and Forbidden city in which used to protect the most important ritual, political area of the court and the working, living area of the King and his family, respectively. The Royal Palace is built in square shape and has 4 gates, however, the main gate named Ngo Mon just served only for the King. It has more than 100 beautiful architectural buildings separated into various areas such as: Ngo Mon gate and Thai Hoa palace where organized the big ceremonies, Dien Tho palace was the residence of queen mother, Duyet Thi Duong (theater), Thuong Thien (Royal kitchen), Cam Uyen garden… Even though most of these architectures were made from valuable kinds of wood, they cannot suffer disasters and the devastation of wars for ages. Therefore, some of them were damaged partly or even collapsed; luckily, the embellishment has been carrying out gradually.