Mystery
concrete block:- (#16 on the layout
map)

At first glance it apears
to be a anti tank obstacle. its basic dimensions are as follows :-
Top: 48" X 53"
Base: 72" X 72"
Height: 3ft
On
the top you can make out where a circular mounting ring was placed,
this was probably used to crane this heavy block into place.
There are also two large notches on the right and left side of the block.
Obviously something was mounted on this block, but what? Perhaps powerfull
naval binoculars? The officer quarters are just above this site.