During Medieval Termoli was the central point of an international traffic network thanks to its relevant position on the Mediterranean coast.

The centre of the old town is the cathedral, one of the most important testimony of the glorious past of this town. 

The cathedral was built between the 12th and 13th centuries on the site of an older cathedral (probably dating back to the 11th century), of which there are still remains of the western triapsidal body and of the rich mosaic floors of the naves and presbytery.

The interior of the cathedral has suffered various transformations. Because of those, the original appearance has been modified. The outside still preserves most of its original decorations.

The decorations on the lower part of the façade are particularly rich, presenting a series of blind arches, including two-light mullioned windows and a central portal.

Both the arches and mullioned windows feature architectural elements (arched lintels and capitals) ornamented with vegetal and figured patterns. Inside the first mullioned window from the left, inserted in the back wall, two sculptures in high relief represent the Annunciation, while remains of another sculptured scene depicting the Presentation in the Temple can be seen in the lunette on the portal.

On the sides of the lunette, two shelves bearing inscriptions on the edges originally supported sculptures of which only the statue of St. Basso still remains.

Both inscriptions, as well as that found inside the lunette on the last mullioned window, refer to the person who ordered the execution of the sculptures. A severely mutilated fourth inscription, located at the bottom of the lunette on the central portal, according to some sources probably bore the name of the architect of the cathedral, Alfano from Termoli.