Urban residence offered political advancement in all three of the duchies under consideration. The presence of the aristocracy stimulated the towns economically, creating a market for the produce of the surrounding countryside and for the outward trappings of wealth and status, including imported luxury goods. The role of Gaeta as a centre of exchange is very visible. Its forum or market-place lay near the palace, and the city's commercial life is evident from documents recording medialoca or warehouses. From their name – ‘middle places’ – these seem to have been constructed above open shops and below living accommodation in three-storey buildings. Gaeta's variety of trades is reflected in the inhabitants recorded in her documents. Not only the duke, his retinue and clergy, but also lime-burners, goldsmiths, a master smith, a painter and a teacher can be seen. In 906, the carpenters of the city were to be found congregated in the platea near the church of St Salvator.

Hints of early trading activity may be found in the presence of inhabitants of other cities in Gaeta. As early as 890, an inhabitant of Amalfi, Gaeta's more famous commercial neighbour, appears as a witness to a document of the ruling family, and one Bonizzo the Pisan is recorded as having owned a warehouse in the city in a document of 1040.