Oxton Village - Christchurch Road Fort?

I was reading through the tunnels thread on here which reminded of an area in Oxton Village, when as a kid we used to mess about in.

On Christchurch, pretty much opposite there is a kind of ruins of an old fort. A circular building with from what i can remember spiral stair case in it. Its only small and very much on show to the publis when walking past etc.

We used to have to climb over the high wall and into its gardens. Who owned it i dont know but the garden were derelict and somewhere in it was a small hole that as kids we could go down a few feet and you could turn left or right only a maximum of 3 or 4 metre. Tho either side was what was obviously a man made stone table and stone bench to sit on.

Can anyone shed any light on this building and what is the history behind it. Ive seached google but can only find the odd photo with no real reference.
This is going back 20 years or so and i think the gardens have now been redeveloped as part of local gardens for new housing.

Thanks

hi jonnyb1978

I'll take a guess that you might be describing a ww2 gun site?

Seems your talking about the other side of the water, you might get abit more joy posing this question here.

Shambo