City in S France whose Roman remains include an amphitheatre and the Pont du Gard aqueduct (5)
I believe the answer is:
nimes
(Other definitions for nimes that I've seen before include "S. France city, Roman remains" , "site of Roman remains in France" , "French city with a well-preserved Roman temple and arena" , "French city after which denim is named" , "City in southern France, giving its name to denim" .)