When not in use?
Humor welcome:
In the shed with the cross bars and the sculls.
That’s a tricky one, you set the bar high here.
I’m sure you’ll find plenty of sphincter storage available, not too far from here!
In the vault, of course.
If you will excuse a serious answer, in my high school they put it inside the folded up gym bleachers.
In the pole vault vault.
At the North and South Pole, of course.