This is the Command bunker and fire control post for the Crisbecq batterie at Saint Marcouf, near Utah Beach - one of the largest bunkers constructed in this part of Normandy.
It’s believed that it was from this viewpoint that the first Allied ships were spotted on the morning of D-Day and there’s a lot of history surrounding this site, it’s commander, and the Allied assault too.
This position was one of the most damaging batteries of D-Day and one of the last to be captured by the Allied forces.
Our good friend owns the bunker and has created an amazing museum inside with a lot of original and fascinating items from the era - guided tours are highly recommended.