Insouciance
Definition: state of nonchalance or indifference
It’s French for “not anxious”
Why I Looked It Up
From Information Hunters:
To the men who had been in distant outpoints, Paris was a wonder. Eating real meals, taking in shows, and strolling the streets, they marveled at the beauty and insouciance of the city.
Not quite sure of the meaning there, honestly.