The Saint-Saloine thermal baths are a quiet Roman ruin, but they matter because they pull Saintes back to its ancient Mediolanum Santonum past. The surviving masonry is fragmentary, yet it gives a useful sense of the scale of public life in the Roman city.
Visit them with the amphitheatre and Arch of Germanicus in mind rather than as a stand-alone blockbuster. Together, those remains make Saintes one of western France's better small cities for seeing Roman history in the open air.