“Looking Glass” was another term for the E-4B Airborne Command Post aircraft; they’re also modified 747-200s, similar to the VC-25s used as Air Force One, but they’re strictly military birds crammed full of top-drawer electronics and command/control systems. They were designed to be used as airborne command posts in the event of a nuclear strike on Washington.
They have a similar (but not exactly the same) paint job to the VC-25s with “UNITED STATES OF AMERICA” titles instead of normal USAF markings. Those pictures, though, are of a VC-25.
}:-)4
Thanks to those “in-the-know” for the explanation re: “Looking Glass”. I always learn something new from you guys.