The magnificent, imposing Thang Long- Hanoi Citadel has stood the test of time over 10 centuries in the land of Thang Long (present day Hanoi). In the Ly Dynasty (1009-1225), the Thang Long (Ha Noi) Citadel was built as replacement for Dai La Citadel. During the dynasties of the Tran (1225-1400) and the Le (1428-1788), the Thang Long Citadel underwent some repairs.
Under the Nguyen Dynasty, Phu Xuan (Hue) was made the capital of the country and the Hanoi Citadel only served as the seat of the General Governor of the North. Therefore, its size was reduced.
The ancient Thang Long Citadel had three encircling walls. Within the inner wall as Tu Cam Thanh (the Purple Forbidden Citadel) where the King and his family lived. This Citadel had been called different through various dynasties: Cung Thanh in the Ly Dynasty, Long Phuong in the Tran, and Cam Thanh (the Forbidden Citadel) in the Le. Doan Mon functioned as the only gate connecting the Purple Forbidden Citadel with Hoang Thanh (the royal Citadel).
The Royal Citadel lied inside the middle wall where royal audiences were held. It also housed offices and residences of mandarins. Time has taken its tolls to many gates linking the Royal Citadel with Kinh Thanh (the outmost wall); only Bac Mon (the Northern gate) in present-day Phan Dinh Phung street has survived.
Common people inhabited the earthen outmost wall, Kinh Thanh. Kinh Thanh used to have many opened gates. During the Le Dynasty, 16 gates were recorded, but by the Nguyen Dynasty, only 12 of them had survived. Of the five gates remaining untilnthe early 20th century (Cho Dua, Dong Mac, cau den, cau Giay and Quan Chuong), only Quan Chuong gate has been preserved to date. The remaining four gates now live in the memory of Hanoians. The vestiges of the ancient earthen wall can be seen at dai La, Hoang Hoa Tham, and la Thanh roads.
For its three criteria of age-old historical and cultural values, being the centre of regional political power for almost 13 centuries without interruption and diversified relic systems, the Central Sector of the Imperial Citadel of Thang Long- Hanoi was recognized as a world cultural heritage site by the UNESCO on 31st July, 2010.
Before that, it has been named among the top ten special national relic sites (first batch) in the decision signed by Vietnamese Prime Minister on August 2009.
As the capital city of Vietnam under the Ly, Tran and Le dynasties, the ancient Thang Long Imperial citadel exits many precious cultural-historical relics to discover.