The documented presence of a bishop in Bari goes back to Gervasius, who attended the Council of Sardica in 347, and his successor Concordius, who was present at the Synod of Rome of 465, although names of their predecessors are preserved by tradition, beginning with Saint Maurus in the 1st century.

One of the mosaic pavements bears an inscription with the name of Bishop Andrea (758 - 761) and it seems highly likely that these are the remains of the first cathedral, which was destroyed in the 9th or 10th century.

The campanile is new, rebuilt from stone similar to that of the original, with an elaborate lantern tower and beneath, the dome of the cupola with clear Moorish motifs.

The church, which had been overwhelmed by Baroque additions, has now been restored to the uncluttered beauty of the original Apulian Romanesque in the transept, in the false matroneum, and in the magnificent pulpit rebuilt from the same material as before.

The silver bust of Saint Sabinus that used to be here was transferred to the capitular archive, and now the icon of the Madonna Odegitria is venerated here: according to tradition this was brought from the Orient in the 8th century, but in reality it is later, although nevertheless a cult object of great antiquity.

In the sacristy to the right is located an altar with a painting which probably depicts Saint Maurus, named by tradition as the first bishop of Bari, in the 1st century.