The Fort can be visited
Fort de Kerbonn

On the coast of Brittany, France, Fort de Kerbonn is a fortress that, as part of the defense lines of the Goulet de Brest, played a strategic role in securing access to the Brest roadstead.
History+
The origins of the fortification date back to 1889-1891, when a mortar battery with an underground magazine was built here. Fort de Kerbonn was designed as a side battery to fire on enemy ships in the Brest roadstead. In 1932, another French battery supplemented the complex. Between 1942 and 1944, the Germans further expanded the fortress.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Armin S.
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: 48.2694, -4.6161