From 1802 to 1945 AD, the city of Hue was the political capital  and one of the cultural, religious and learning centers of Vietnam.

The city's many historical monuments, such as the Citadel, are silent witnesses of this glorious past (fig.). The Hue Citadel consists of a large, walled area on the North side of the Perfume River.

Within its walls is the Imperial City which in turn encloses the Forbidden Purple City, and which is modeled along the lines of the Forbidden City in Beijing (fig.).

It likewise was once reserved for the emperors of the Nguyen Dynasty, their concubines, and those close enough to be granted access, the punishment for trespassing being death.