Something which the Americans want to keep in an out of the way place ? First of several wild guesses - US. forces personnel being treated for drug addiction ?
No - the people in it are perfectly ordinary & normal, as much as one can be living in such isolation I suppose. There are only two ways to get there - by sea or by driving through a long, one-lane tunnel through the mountains.
Tunnel through a mountain seems a fair guess looking at the surrounding countryside. Most town halls here used to have a school attached, so is it a government building?
No - although her existence could well be the cause of people living there. Remember, there's not just a school under the roof...
You could say that, but it is something rather more unique - the only one of its kind in the world as far as I'm aware. Looking at the picture, can you see any other buildings?