It has a complex and richly-decorated symmetrical façade, with a central entrance area flanked by two square towers topped by crosses.

The façade is ornamented with pilasters, corbelled brick panels, and niches in which statues are mounted.

The interior is also richly ornamented and has a coved plaster ceiling which have been painted with artwork by Dominique Canova.

Its stained glass windows are Bavarian in origin, coming from F. X. Zettler.

[3] Completed in 1857, St. Alphonsus served as a parish for the Irish Catholic community of the Lower Garden District section of the city.