Dien Khanh Citadel

Dien Khanh Citadel is a well-preserved Vauban-style military fortress located in Dien Khanh Town, about 10 km west of Nha Trang in Khanh Hoa Province, Vietnam. Built in 1793 by Nguyen Anh, later Emperor Gia Long, with assistance from French officer Olivier de Puymanel, it served as an important administrative and military center. Notable for its earthen walls, moat, and four arched gates, it is one of the oldest citadels in southern Vietnam.

Visitors can expect a historic earthen citadel with a rectangular Vauban layout surrounded by a moat and 3.5-meter-high walls. Four original arched gates remain at the east, west, south and north, with the east gate being the most intact. Inside the walls is a small residential area with local houses and gardens, while the exterior offers views of the moat, ramparts, and tree-lined paths. The site is open and quiet, suitable for walking, photography and observing 18th-century military architecture.

Built in 1793 by Nguyen Anh, who later became Emperor Gia Long, with technical assistance from French officer Olivier de Puymanel. Constructed in the Vauban style, it served as a key military and administrative stronghold during the Tay Son - Nguyen conflict and later as the administrative center of Dien Khanh and Khanh Hoa under the Nguyen Dynasty. It is recognized as a national historical relic.

Represents late 18th-century Vietnamese military architecture combining Vietnamese and European Vauban design principles. It remains a symbol of Dien Khanh's historical identity and is valued as a heritage site illustrating the Nguyen Dynasty's fortification techniques and urban planning.