Rába-Quelle is Győr's main thermal-bath complex, using hot mineral water in a mix of medicinal pools, leisure pools, saunas, and family areas. It is not as grand as Budapest's historic bathhouses, but it gives the city a properly Hungarian way to spend a slow afternoon.
The baths are most useful if you are staying overnight in Győr or breaking a journey between Vienna and Budapest. After a morning in the Baroque old town, soaking here makes more sense than trying to turn Győr into a museum checklist.