I don't think you could go inside the aircraft when I was there, maybe 20 years ago?
Lot more than 20 years ago the LAST time I toured it.
Back then, you could look into the pilot's seats - manequins in each "HRH, Jr." in the left seat - off a catwalk through plexiglass, could enter off another gangway to inside the back several rows - only - of the cabin, just behind the engineer's positions, one per each engine, same side and order as they were on the wings. Yah could get TO them from inside the wing whilst in flight AFAIK. B-36 had that feature as well. And needed it.
They had a barrier riband and some cover plating on the floor to stiffen it and prevent wear.
It looked more like a classroom set up to teach on simulators than an actual aircraft, it was that spacious.
Finally, there was a low-level walk through the side hatches into the cargo belly, also on treadway so folks didn't touch the actual aircraft. I THINK they had a genuine restored Sherman tank, not a replica, in the cargo hold, but it was quite a distance away and "glossy" painted as if for a parade, not battledress, so cudda been a Hollywood stage prop.
He flew it, that one time..
But my opinion is he discovered it didn't have good enough lift to drag ratio to get up out of "ground effect" or he WOULD have done that, as for his "taxiing test" there was only partial fuel, a crew, and the few VIP witnesses / passengers, no cargo nor much - if any - ballast!
My Grandmother.. ISTR had her first child same year the Wright Brother's first flew. In her 90's before ever she set foot on an aircraft.
Dad drove her to Pittsburgh from Weston, WBGVA, so they could do it in one go. Nonstop 747 to LAX to visit his elder brother.
He stops her by the windows after they had debarked, pointed, nose-on, to "Fat Albert", said "Isn't it a MARVEL mankind can make something that big and have it fly!"
G'Mum was no dummy. Clocked a full Scholarship to State Teachers's Collitch coming off seventh grade, one room-schoolhouse, and never stopped reading.
She just looks at him as if he was still five years old, sez:
"After all the work and money put into it?"
"It would be a far
bigger surprise if it did NOT fly!"
Old timers aren't amazed by the march of progress.
We've been in the ranks of that march, the whole damn time, calling cadence - now and then leading various bits of it.