A brick Lombard Romanesque church whose broad gabled front is edged with corbelled blind arcading in buff terra-cotta and centered on a large rose window of radiating tracery beneath a cross-topped peak. Three recessed round-arched portals open below; the central one is framed by concentric molded archivolts and twisted colonnettes, with DOM DIVO AMBROSIO cut in its lintel. Round-arched windows and corbel tables in the same buff terra-cotta trim the red-orange brick. Behind the front, a long basilican nave lit by round clerestory oculi runs back beneath a red tile roof, ending in a low crossing tower.
The parish was founded in 1903 to serve the Italian immigrants who had settled on the Hill, many of them drawn to St. Louis to work on the Frisco and Missouri Pacific railroads. Its first frame church, built that year, was destroyed by fire in 1921. Angelo Corrubia designed the present church, built in 1926 and modeled on the Basilica of Sant'Ambrogio in Milan. In the 1970s the sculptor Rudy Torrini added the bronze group in the forecourt, The Italian Immigrants — a man with a suitcase and a woman holding a child — as a memorial to the neighborhood's founders.
