A huge complex with all the executive and bureaucracy one would anticipate from a nation's capital formerly stood as the Imperial City of Hue. It was surrounded by a square castle, also called the Hue Citadel, whose four walls were each roughly two kilometers long and had a large moat on the outside.
The Imperial Palace, where the Emperor and his closest advisors resided and worked, was known as the Purple Forbidden City. It used to be out of reach for the majority of people. Naturally, we can all now walk through it and see what is still there.