Lair is a pretty good word for the place. OK, so it wasn't carved from a volcano, and there's no hidden dock for submarines (to the best of my knowledge). But it's still a relatively normal office building that, like an iceberg, is vastly bigger beneath the surface, and cloaked in the type of security that you'd otherwise expect to find at the Pentagon. It should go without saying that my camera was strictly forbidden, and whenever my phone was out, multiple pairs of eyes were glued to it to ensure I didn't do anything stupid, like try to somehow sneak a shot.
Like I said, I'd been here before. In 2014 I was doing some interviews ahead of the Mustang's 50th anniversary, so I had a cursory familiarity with the building and its long, wide, industrial-looking subterranean corridors, lined with sporadic posters of righteous concept cars from years past.