I do know the tower which you mean, and for some reason I had always thought it was a lighthouse, but I cannot remember where I got that from.

I have now spoken to someone who has been in it, and have been told that it appears to have been 'just a feature' as part of the holiday amenity area, judging by the pathway round it, and having been in it, this person tells me that there are, if you look up with caution, lots of little alcoves, which strongly suggest a pigeon coup. Makes sense?