The so-called Temple of Diana is a 1st-century ancient Roman building in Nîmes, Gard, built under Augustus. It is located near the gushing spring of "La Fontaine", around which was an Augusteum, a sanctuary devoted to the cult of the emperor and his family, centred on a nymphaeum. Its basilica-like floor plan argues against it being a temple and there is no archaeological or literary evidence for its dedication to Diana.
The building may instead have been a library. Its facade was rebuilt during the 2nd century and in the mediaeval era it housed a monastery, ensuring its survival.
Wikipedia https://en.wikipedia.org/wiki/Temple_of_Diana_(Nîmes)
Address 11 Quai Georges Clemenceau, Nîmes 30000, France
Coordinates 43°50'23.586" N 4°20'54.688" E