The church in Apulian Romanesque style has a salient facade with the central part remarkably high compared to the side, symptom of a late Romanesque and anticipation of the subsequent Gothic style. The pilasters show the tripartite scanning of the interior in naves. The main portal is surmounted by an archivolt with bas-reliefs. Christ is present with two pilgrims, the Virgin Mary and Saint John the Baptist, with the presence of the twelve apostles. The upper part of the facade has a rose window with demons and angels. Above the rose window a seated figure of man, among the possible interpretations there is that of recognizing the one who financed the work, namely Robert II of Bassavilla.

The co-cathedral is dedicated to Santa Maria Assunta. It was built between 1100 and 1200. In Apulian Romanesque style, it already presents some anticipations of what would have been the next Gothic art. It has undergone several restorations during the Renaissance between 1400 and 1500 with the addition of altars and chapels inside. During the 20th century all the decorations, especially the baroque ones, were removed to bring the church back to its original style. Archaeological investigations of 1974-75 brought to light an area of the city with a continuity of use without interruptions from the Peucet phase to the Roman one. Below the medieval cathedral, in this area of the ancient city had to insist a necropolis of Peucet era, as well as small portions of a residential and productive district, due to the presence of a furnace. The Peucet tombs have returned part of the equipment, while for the Roman phase, the domus intercepted were characterized by mosaic floors. On these structures, between the high and the low Middle Ages it was decided to build a church building with a bell tower used as a watchtower.