The protected natural site of Mont Canisy dominates the sea from its 110 m. From 1935 to 1940, the French Navy installed two batteries there to help secure the estuary and the Port of Le Havre. Then, from 1942 to 1944, this site became an important link in the “Atlantic Wall”. Various elements (casemates, bunkers, shelters, fortified structures connected by a 250 m long gallery, etc.) remain.

Free guided tours are regularly organized by the association "Les Amis du Mont-Canisy".

Hill steeped in history, in turn seigneurial fiefdom divided up in 1793, anti-submarine defense post in 1917-1918, coastal battery between 1935 and 1940, the most important artillery fulcrum of the “Mur de l ' 'Atlantique' between Cherbourg and Le Havre from 1941 to 1944, its position facing the Port of Le Havre and the bay of the Seine earned it, during the last world conflict, to be transformed into a concrete fortress.

Numerous vestiges remain from this last period: casemates and tanks for 155mm guns, bunkers-shelters, protection tobrouks, fire direction post ...
But the most attractive element of the guided tours remains the underground structure, with its 250 m of tunnel, 25 barracks, six stairs providing access to the surface, 25 ammunition bunkers, ... 15 m underground , a unique structure covering more than 150 km of Normandy coast!