You can see this building (the other side of it though) when you drive on the A34 North of Oxford.
I've always wondered what it was, so today I went for a good look around. It used to be a Grain Store* and, as you can see, it's now derelict.
It seems to be quite well fenced off, I have a huge urge to go inside and have a proper nose around... maybe I'll do that sometime
* Alright, I found that out by Googling when I got home