Cap Gris-Nez
After the Germans defeated France in 1940, they began to establish several coastal batteries along the English channel. This because they would pose a threat to British maritime traffic, but also as support for a possible German invasion of the English mainland. One such coastal battery was located south of Pas de Calais at Cap Gris-Nez and consisted of four artillery bunkers. The GUns installed could easily reach England only about 35 kilometers away. When an invasion was no longer relevant, the battery became part of the German Atlantic Wall. In memory of the late Fritz Todt, the head of Organisation Todt, in February 1942, the Battery was called Todt.
Current status: Partly preserved/demolished with museum (2017).
Location: 50°50'39" N 1°36'01"E
Get there: Car.
Follow up in books: Saunder, Anthony: Hitler’s Atlantic Wall (2014).
In one of the bunkers there is a museum and the others are abandoned but can be visited regardless of the time of day. As always with bunkers, you should be careful where you place your feets and despite their size, they (at least two of them) are not necessarily easy to spot because they are hidden among dense vegetation.