The entrance has a portico with 28 antique columns whose pointed arches, with lava rock intarsia, show influence of Arab art, and contains a series of ancient Roman sarcophagi.

Artworks include two pulpits with mosaic decorations, paintings by Francesco Solimena, a 14th-century Gothic fresco of Madonna with Child and the sepulchres of the Neapolitan queen Margaret of Durazzo, of Roger Borsa and of archbishop Bartolomeo d'Arpano, and the tomb of Pope Gregory VII.

The Cathedral is visited by thousands of tourists from all over the world and has two important additional sections: the Duomo Museum and the Cripta with Saint Matthews remains.

The "Duomo Museum" houses artworks from different ages, including the silver statues of the Salernitane Martyrs (13th century) and documents of the renowned Schola Medica Salernitana (the first University of Europe, according to some scholars like G. Crisci).

This Crypt, with the remains of Matthew the Apostle brought there in 954 AD, is a groin vaulted hall with a basilica-like plan divided by columns.

All of the ceiling frescoes are painted by Belisario Corenzio and depict scenes from the Gospel of Matthew, as well as some episodes of the history of Salerno (such as the siege of the city by the French).