The Église Saint-Louis is the principal Roman Catholic church of Vichy, a substantial nineteenth-century building in a neo-Gothic style that fits the general ambience of the thermal district. It is not an exceptional church by French standards, but it is a well-executed example of the period's religious architecture, and the interior has some good stained glass and decorative details worth noting. The church sits at the quieter, residential end of the central district, away from the main thermal circuit.
More interesting historically is the church's role during the Vichy regime years: like most of France's Catholic institutions, it operated throughout the occupation, and several senior clergy in the region were publicly supportive of Pétain's government. A visit here, like a visit to any of Vichy's older institutions, carries that background awareness whether you want it to or not.