According to the Criterion (ii), “Mantua and Sabbioneta are exceptional testimonies to the exchange of influences in Renaissance culture. The two cities played a prominent role in the spread of Renaissance culture within and beyond Europe.”
An example for all: the Palace of Charles V, within the grandiose complex of the Alhambra in Granada, is clearly inspired by the architectural structure of Te Palace. Charles V had admired the palace during his visit to Mantua in 1516, and was impressed by it. Some attribute the design of the Palace of Charles V to Giulio Romano himself.
The Palace of Charles V in Granada
On the other hand Vespasian Gonzaga, as well as Sabbioneta, designed in 1571 the Citadel of Pamplona, for the purpose of protecting Philip II's Spanish possessions. The fortification reflects the principles later applied to Sabbioneta: the inspiration from classical architecture, the synthesis of military needs and aesthetic form, and the design of the walls and bastions.
The Citadel of Pamplona