A couple of years ago I was privileged to get a tour of the super secret Smithsonian storage facility in MD.
https://en.wikipedia.org/wiki/Smithsonian_Museum_Support_Center
We saw such delights as a ton of samurai armour, a stuffed polar bear and easter island type head on a shelf, and Roosevelt's favourite dog.
Some of the tags had double digit serial numbers and we were told that a lot of this stuff will probably never be displayed in public due to the sheer size of the collection.
I'll see if I can find the pictures.