Fortifications of Vauban
The Citadel and the ramparts at Saint-Martin-de-Ré was fortified by Vauban following a siege at La Rochelle by the English in the 17th century.
For a number of years the Citadel served as a gathering place for convicts before leaving for New Caledonia and La Guyane.
It was then turned into a prison which is still in use today (over 400 prisoners).