Abandoned WW2 bunkers

 Casemate Type 623, Koudekerke, The Netherlands.

 Radio Transmitter Bunker, Spaandam, The Netherlands.

 Type 669 Heenschemolen, The Netherlands.

R636 Fire Control Post, Lekrinckoucke/Zuidcoote, France.

 SK Observation Tower, Fliegerhorst, Belgium.

 Type 703, Emminkhuizen, The Netherlands.

 Type 583a / M 178. Fire Control Post. Heerenduin, Ijmuiden, The Netherlands.

Dragon's Teeth Anti Tank Defence, Den Helder, The Netherlands.