Discoveries of old foundations under the St. Peter's Church and old graves under the St. Stephen's Cathedral have disputed the certainty of this label.

According to legend, the church was founded by Cunald and Gisalrich, companions of Rupert during his occupation of the seat of bishop of Salzburg.

The arch on the western gallery has a plaque with the label “AEIOU 1439”, an undecyphered motto of Emperor Frederick III.

According to tradition, AEIOU stands for (in Latin) "AUSTRIAE EST IMPERARE ORBI UNIVERSO" or in German "ALLES ERDREICH IST OESTERREICH UNTERTAN", both meaning "The whole world is subject to Austria" A relic of the sarcophagus of Saint Vitalis is located in the church containing the supposed remains of a Christian victim from the Roman catacombs.

This memorial of victimization has special meaning in modern times because the Gestapo headquarters, which was used for torture and the organization of Jewish deportations, was located nearby in the Morzinplatz square.