the special atmosphere of a place

the guardian spirit of a place

(as above): the genius of the place

The distinctive atmosphere or pervading spirit of a place. The guardian deity of a place.

In Roman mythology a genius loci was the protective spirit of a place. It was often depicted as a snake. In contemporary usage, "genius loci" usually refers to a location's distinctive atmosphere, or a "spirit of place", rather than necessarily a guardian spirit.

Genius Loci is a novel by Ben Aaronovitch, focusing on the early career of Bernice Summerfield, a character from the spin-off media based on the long-running British science fiction television series Doctor Who.