Mea culpa, you are correct. I've been there several times for technical conversations with investigators, but it's been many years and most of the time they were held in someone's office or conf room. I now vaguely remember getting a quick tour of some of the spaces (and recall that the room for CVR work had special, extra-limited access for obvious reasons). But as you said I think you would need to know someone to be able to visit/tour the place; it's not accessible via just a request from the member of the general public, correct?