Think level 2 below ground level. We live from the ground up in the open for all to see. These people want as far away from the light of day as they can get!
Good point and my apologies for the delay in response. (Most of The Homestead's acreage is leased out, but I still have to get out and make sure no critters have gone adrift.)
While I was riding around I was musing on a possibility that complicates that observation:
First challenge would, of course, be finding a way to have the CIA allow a bunch of us amateurs to come troop around "their" headquarters and poke into absolutely ANYTHING. (I'm just sittin' and grinnin' while I recall the last run-in I had with a CIA type....)
Then, as generally devious as those Spooks are, that Coordinates+Elevation could very well be as straightforward as it sounds, but then only be the first step in a Grand Scavenger Hunt that would make your hair fall out.
Did you ever watch "National Treasure"?