Citadelle Vauban du Palais, Military citadel in Le Palais, France.

The Citadelle Vauban du Palais is a military fortress on Belle-Île-en-Mer built with six granite bastions and structures that once housed thousands of soldiers. The complex sits near Le Palais harbor and displays the layout typical of classical French fortifications.

The first fortifications at Le Palais date from the 14th century, when Belle-Île belonged to the abbey of Sainte-Croix de Quimperlé. Around 1550 François de Rohan-Gié built a square bastioned fort; Albert de Gondi rebuilt it from 1549 using sandstone from the demolished Château de l'Hermine in Vannes. Vauban stayed in 1683, 1687 and 1689, adding a double enclosure and corner bastions. The English took the citadel in 1761 after a month-long siege and held the island until the Treaty of Paris in 1763.

The citadel houses a museum displaying regional artifacts, historical documents, and maritime collections that reflect the island's connection to the sea. Visitors can see old maps and naval objects that show how this fortress related to seafaring traditions.

The citadel stands on the right side of the harbour entrance, opposite Le Palais, and is reached on foot from the town. Its irregular square plan with added corner bastions forms a star shape, so allow time to walk the ramparts and the lower terraces. The granite surfaces and outdoor paths are exposed to wind and rain off the Atlantic.

On 12 August 1960 the citadel, listed as a monument historique since a decree of 1 May 1933, was sold at auction by candle for 41,923.48 euros to André and Anna Larquetoux, who were visiting Brittany for the first time. The couple restored the abandoned fortress and opened it to visitors.