Building 2 is likely a storage of food since so many footsteps go to it and everyone needs food daily. Since building 3 is being guarded, I suspect either a prisoner (future workers) or silver (valuables) will be stored here. Since the goblins didn't fight with good weapons, I doubt we can find a store of good weapons (otherwise they would have used better weapons in battle). I have no idea what would be in the creepy building and building 1 is likely just an access to the ballista tower. So.... let's see what is inside the guarded building 3.