When you say "largest building by interior volume" I guess you mean it had the biggest single room with no walls, floors, or support beams interrupting the space. Tho not as tall, Madison Square Garden, built a year before the VAB, seems a far vaster space than the VAB interior. I'm only speaking subjective impressions, but I stand by my disappointed first, and following, impressions. The VAB is overhyped and they ought to get over it. PR is important for NASA, and many of their visitors are from big cities where they see bigger buildings all the time. NASA should stop disappointing their fans with overblown claims about a gigantic building and focus on the function. They do amazing things they can be proud of. This building may have been impressive at one time, but it isn't anymore.