The construction of Hue Citadel was commenced in 1801 by Emperor Gia Long. This followed a period during which the Nguyen Lords moved the capital around the surrounding area. Since the initial construction, the citadel has been altered and improved upon by a number of Emperors including Emperor Minh Mang, whose tomb is not far from modern day Hue city.
Unfortunately, Vietnam’s history of war has boded ill for the citadel, and much of the interior, particularly the Forbidden Purple City, has been destroyed. It was during the conflict with the Americans that some terribly bloody and vicious fighting took place, which flattened a lot of the inner city. However, some parts do still remain and will give you an idea of what a magnificent imperial capital Hue must have been.
The Citadel is almost 10 km in circumference and its walls are 6 m high and 20 m thick. The moat encircles the entire Citadel and is 23 m wide with a depth of 4 m. There are ten entrances to the citadel, many of which are now bridges and roads into the Citadel area (where people live and farm).