Hue capital in the 19th century was the gathering place for the quintessence of the country after the territory and government were unified. Here, national power in terms of managing the state apparatus, territory, sea and islands, population... has been strongly demonstrated. Hue imperial capital in the 19th century was also the place where many new national architectural works were built and many achievements in the architecture of ramparts and palaces of the world were built, including the citadel, palaces, mausoleums and pagodas... with interesting landscapes, giving Hue a unique architectural style, a unique culture including food, costumes, houses, music, theater, festivals, religious lifestyles... Hue Citadel in the 19th century has become a world cultural heritage with a variety of categories: tangible (architectural heritage); intangible (Hue Royal Refined Music); memory (Administrative documents of the feudal period; Poetry on Hue royal architecture).