The Fort can be visited
Fort de Fouras

In the French commune of Fouras is the Fort de Fouras, often mistakenly called Fort Vauban. It is an example of historical coastal fortifications.
History+
The strategic importance of the Charente estuary was already recognized by the Romans, who built a castellum there. The origin of the current fortress dates back to the 11th century when the Rochefort family collected tolls from ships here. In 1305, Philip IV acquired Fouras, bringing it directly under the crown, before it was later granted as a fief. Between 1480 and 1490, Jean II de Brosse had the current keep constructed. After the siege of La Rochelle in the 17th century, Louis XIII spared Fort de Fouras due to its strategic importance and declared it a royal fortress.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Hervé Rebours
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 45.9860, -1.0974