What to see

The port area around Cherbourg was one of the most heavily defended areas in Normandy, as is normally the case with important strategic locations such as this.
Today a large part of it is still out of bounds as it falls inside the French Navy site, but there are a few bunkers to be found for concrete tourists.

These are around the Citi de la Mer site and include a R631 type casemate for a 4.7cm Skoda-made fortress gun in the car park for the attraction.
At the end of the pier that is part of the Citi de la Mer site - just a few yards away from the Le Redoutable nuclear submarine - is a R649 casemate which housed a 105mm cannon inside and also featured a position on top for an anti-aircraft gun.

The Citi de la Mer is worth the entry fee just to be able to go inside the submarine, but there's also an amazing aquarium and Titanic experience which eventually takes you into the old railway station area of the docks which were heavily bombed during the war. The walls inside the railway buildings have huge pictures of what the site was like in 1945.