Cathedral was built in Romanesque style in XI century and modified several times. The bell tower, of great historical and artistic value, is an important witness to the fusion of Arab-Norman period. On it are placed eight large bells. Baroque facade opens on a staircase. Of the prospect remains the portal, Lions Gate. In general, the sculptural decoration is characterized by a strong presence of animals. The portal leads to a large atrium, only example in addition to Sant'Ambrogio, of Romanesque portico in Italy. Atrium, surrounded by a colonnade, it opens Bronze Door, cast in Constantinople in 1099. Between the bell tower and facade in '700 was added to another part of the building, the so-called Auditorium of Santa Caterina. Although domains within one seventeenth-century style, were found Medieval tracks and in one of the side aisles you can admire frescoes by Giotto school. Original mosaics are those of the right aisle. Under the altar is the urn of Pope Gregory VII, who died in exile in Salerno. From the sacristy it leads to Chapel of Treasury, with a remarkable painted ceiling depicting the so-called "Salerno Paradise", painted by Filippo Pennino. Very beautiful is the Crypt which houses mortal remains of St. Matthew. All the ceiling frescoes are work by late-Mannerist painter Belisario Corenzio and depict scenes of Matthew's Gospel.