I went on a tour of Boeing's manufacturing plant in Everett, Washington(fyi it sucked, you don't get anywhere near the planes while being built).
However the building was fucking huge. Unbelievably huge.
Some facts and figures:
The Pentagon is roughly 77 million cubic feet in volume.
The Boeing manufacturing facility is 472 million cubic feet in volume.
And that doesn't include the paint facilities or the other testing facilities on the property.
Makes me go whoa.