The Cathedral rises on the remains of an early Christian temple between the 11th and the 14th century. The predominant style, though several reconstructions occurred during the centuries, is the Romanesque style, with a Latin cross plan, three aisles, transept, apses and bell tower.

In 1359 the restoration work on the whole complex started: the rose windows on the main façade were opended and the decorations completed. Around 1877 a project to restore the original Romanesque architectural structure and to remove the baroque elements was proposed; though the local population firmly opposed this project the terrible fire on the night between 10 and 11 July 1911 favoured the restoration.

Since the Cathedral is not surrounded by other buildings, it is possible to walk along the lanes and narrow streets that surround every side of the church as to observe better its architectural structure and to study its sculptures. The Cathedral of Conversano diverges, together with that of Ruvo, in its originality from other Apulian-Romanesque examples.

In 1997 the Cathedral, dedicated to the Assumption, was elected Minor Basilica by Pope Giovanni Paolo II.