Okay last picture was slightly WW2 related, as castle Loevenstein was part of the Nieuwe Hollandse Waterlinie, our 2nd line of defense, sadly, or should I say luckily, not used.
The next is really WW2. During the years, the Germans strengthened the coast against an invasion. They failed as we all know, but they left some impressive coastal defence bunkers all over the coast Here in the Netherlands this can be seen in Hook of Holland, not far from Rotterdam and The Hague. In the dunes, you find n extensive tunnel network, linking many shelters and gun placements. You can visit them under supervision of a guide.
In the second one, you can see my little tunnelrat Kiran in the distance, wearing a red shirt.