Pantheon's city (4)
I believe the answer is:
rome
'pantheon's city' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rome that I've seen before include "Seat of Italian empire" , "church" , "Colosseum city" , "When here, do as the citizens do" , "When there, do as the native do" .)