The late 15th century Baia Castle was built by the over ancient Roman ruins thought to be the summer residence of Julius Caesar. On the 29th September 1538 the great eruption, with devastating effects for all the Phlegraean Fieldsi, caused serious damage to the Castle of Baia too. The castle was restored and enlarged by the viceroy don Pedro Alvarez de Toledo.
Today, this cliffside Aragonese castle with sea views is home to the Archaeological Museum of Campi Flegrei.
The historical centre of Briançon is a strongly fortified town, built by Vauban to defend the region from Austrians in the 17th century. Its streets are very steep and narrow, though picturesque. Briançon lies at the foot of the descent from the Col de Montgenèvre, giving access to Turin, so a great number of other fortifications have been constructed on the surrounding heights, especially towards the east.
The Savoyards made two raids into French territory in 1691 and 1692. As a result, Vauban was dispatched to inspect the frontier defences, which had been ill-equiped to deal with the attack from Savoy. He returned to the area in 1700 to check on the progress that had been made since his first visit. When Vauban visited Briançon, work on the defences had already started under a local engineer, Monsieur d"Angrogne in 1692.