The Rocca Paolina was not the first fortress to be erected in the city of Perugia. During the military campaigns of Cardinal Aegidius Albornoz, who tried to reconquer the territories of Tuscia and Umbria on behalf of Pope Innocent VI, exiled in Avignon, Perugia fell once again under papal dominion (Peace of Bologna, 1370). As proof of the renewed dominion, in 1373 Albrornoz ordered a fortress to be built, the Rocca del Sole on the highest point of the town, the Colle del Sole. Built according to plans by Gattapone da Gubbio, the fortress was the largest and best known of its time. Nonetheless if was completely destroyed by local citizens in a uprising just three years later. All that remains of it are the massive substructure walls that support what is now Piazza Rossi Scotti, formerly delle Prome, but usually called Porta Sole, from where there is a splendid view eastwards towards the Apennines. In 1540, during the pontificate of the Farnese Pope Paul III, Perugia was last free city in Italy and was finally defeated in what is known as the Salt War. As a sign of the renewed papal dominion, the Pope commisioned Antonio da Sangallo the Younger to build an imposing fortress, this time on the city's other hill: Colle Landone. The entire district of Borgo San Giuliano was rased to the ground to make way for the fortress, including all the houses of the Baglioni family that the Pope so hated. Over a hundred houses, as well as churches and monasteries were destroyed and used as building material and as substructures for the fortress. This time the citizens of Perugia had to wait until the Roman Republic of 1848 for a first, partial demolition of the loathed symbol of papal power and finally until 1860 with the unification of Italy for its final destruction. Externally, the only visible parts of the fortress are the substructure walls along Viale Indipendenza and the eastern bastion in Via Marzia, which incorporates the Etruscan Porta Marzia. From here it is possible to enter the foundations of the fortress, which rested on vault structures placed over the houses and streets such as Via Baglioni The stone houses, with their Gothic doorways, are still clearly distinguishable from the brick-wall foundations added by Sangallo.