When I was in the Air Force, I flew inside a C5 from Kadena AB in Okinawa, Japan to Travis AFB an 11 hour non-stop flight {in May 1980 so that I could see "The Empire Strikes Back" in Hollywood}. It was weird to fly in the back of the plane as you are up near the roof and the seats face the rear.
Saying the C5 is huge is an understatement.