This casemate built in A is a true monster and so it deserves its own special. It was specially designed for the 17 cm K18/L50 gun in Mörserlafette. It could fire grenates of 68 kg over a distance of 28 km. Bunkertype 689 had the same gun, but with a different lafette.
A demolished 688 in Katwijk, the Netherlands. (John Burgmans' collection)