Flag tower in Hue, the former imperial capital of Vietnam. Located on the Perfume River in central Vietnam, Hue was the capital of Vietnam from 1802 until 1945. A walled citadel, 2 km by 2 km, as well as a moat, surrounded the city. Inside the citadel was the Imperial City. Many of the buildings of the Imperial City were destroyed during the Vietnam War. Some reconstruction has begun.