Good thinking Vidman
I was attached to the Pentagon, NATO Standing Group, and Embassy Row, for over three years. Arrived just before JFK was assassinated.
Even way back then the FBI and T-Men and Secret Service and many of the Embassies, made a major project out of Public Relations; wanted to let the people know how they were spending our tax Dollar. Often you could arrange special tours, specific to your main interest.
Should be a real motherlode of information. Would easily repay a working vaction. But, after 9/11, might be a good idea to invest in a letter, including a selfaddressed stamped envelope, testing the likely cooperation you could expect.