The Temple Saint-Étienne is Mulhouse's main Protestant church, built in the fourteenth century as a Catholic church and converted to Protestant use at the Reformation in 1529. The exterior is Gothic, and the interior retains a collection of exceptional medieval stained-glass windows dating from the fourteenth and fifteenth centuries — some of the finest in Alsace. The church was substantially restored in the nineteenth century and the newer glass in the nave is noticeably less interesting than the medieval originals in the choir.
Mulhouse became Protestant in 1523, among the earliest cities in France to do so, and the church's history mirrors the city's complicated identity — Alsatian, German, Swiss, and French by turns.