The city of Aversa arose in the 11th century,[4] near the destroyed Atella, and became the seat of the Norman invader Rainulf, who became a vassal of Duke Sergius of Naples.

[5] In September 1089, Pope Urban II consecrated the monk Guitmund, who had been an agent of the Holy See, as Bishop of Aversa at the Synod of Melfi.

[6] An immediate protest was lodged by the Archbishop of Naples through his Archdeacon, and by the Prince of Salerno and Amalfi through his legate, humbly requesting that possession of the Church of Aversa be returned to them ("ut sibi tandem Aversane ecclesie possessio redderetur").

In his reply to the Archbishop, Pope Urban stated that he had consecrated Bishop Guitmund neither out of anger or hatred, but for the sake of equity and compelled by necessity, lest the Church of Aversa lose such a man as he had appointed.

[7] In a letter to Bishop Guitmund, Pope Urban stated that he and his advisors and the Roman leaders had debated the issue of the possession of the Church of Aversa for some time ("diu causam eventilavimus"), the unanimous decision was that the investiture of the possession of the Church of Aversa should be returned to the Archbishop and the Prince.

[11] The cathedral was begun thanks to the munificence of Duke Robert Guiscard, was carried forward and completed by his son Jordanus.

[12] The cathedral was served and administered by a corporate body, the Chapter, which was composed of four dignities (the Dean, the Cantor, the Archdeacon, and the Subcantor) and thirty Canons.

He succeeded Archbishop-Bishop Mario Milano, whose resignation was accepted by the Pope on the grounds that he had reached the canonical age of retirement of 75.