Hue (Vietnamese: Huế) is a city in central Vietnam that was the capital of Đàng Trong from 1738 to 1775 and of the Nguyen Dynasty from 1802 to 1945. A major attraction is its vast, 19th-century citadel, surrounded by a moat and thick stone walls. It encompasses the Imperial City, with palaces and shrines; the Forbidden Purple City, once the emperor’s home; and a replica of the Royal Theater. The city was also the battleground for the Battle of Huế, which was one of the longest and bloodiest battles of the Vietnam War.
Source from Wikipedia