Doe's Island Castle
a very long telephoto shot
Long-distance only
From the ramparts of Bamburgh Castle in Northumberland, you can see (waay off in the distance) the outline of a small tower on Does Island. It can also be seen from Lindesfarne, but we missed the tide to get to the priory there.
I don't know anything about the castle, really - it look sike a small l-plan tower with modern windows.