Re: "in keeping with its surroundings and help minimise the visual impact"
Thereby demonstrating either incredible ineptitude in the arts of secrecy or incredible cunning in the same.
Nobody really bothers trying to keep the exterior of secret facilities secret any more - complete waste of time with modern reconnaissance technology and the length of time these facilities are supposed to remain secure. However against this trend some organisations do still try to conceal the location of their key sites; National Grid's national control centre being one example, about a mile away from me. We all know where and what it is, guys!