Roberto il Guiscardo or Roberto d’Altavilla (1015 /1085), was a norman adventurer. On December 13, 1076 Roberto, who had married Guaimar IV's daughter Sichelgaita, besieged Salerno and defeated his brother-in-law Gisulf. This act put an end to hundreds of years of Lombard dominance, but did not check the city's vitality.

Together with the bishop Alfano, Roberto decreed his hegemonic role by transforming the city of Salerno into the capital of the Norman kingdom through the construction of monumental architecture, such as the royal palace (Castel Terracena) and the cathedral of San Matteo, built of peculiar aerariums with precious marbles recovered for their beauty and sense of antiquity. The columns and capitals originally come from Ostia, Campi Flegrei (macellum di Pozzuoli) and later from Paestum.

Blocks of travertine from the walls or temples of Paestum were also used for the construction of the base of the bell tower of the Salerno cathedral. The base is made up of large parallelepiped blocks reassembled in order to evoke the reconstruction of an ancient factory. The architectural structure of the bell towers, as a whole, explicitly refers to the Roman defensive towers.

According to the geographer Al-Idrisi, author of the first descriptive atlas of the world known at the time "The book of King Roger II of Altavilla", in 1139 Salerno was an illustrious city, it had thriving markets, public amenities, wheat and other cereals.