The Aragonese Castle is located in the Baia, in the hamlet of Bacoli. His position, which overlooks the Pozzuoli Gulf until Procida, Ischia and Cumae, allows a broad control of the area, preventing the approach of enemy fleets. The construction of the Castle was started by the Aragonese in 1495, just before the French invasion of King Charles VII. After the eruption of New Mount, the Spanish Viceroy Pedro Álvarez de Toledo started a radical restructuring and expansion of the Castle, after which it took on its present appearance, in the shape of a star. After the Unification of Italy, the Castle had a period of slow decline and inevitable abandonment. Considered most useful not for military purposes, in 1887 it came under various Ministers. In 1984 it was finally handed over to the Archaeological Superintendence of Naples and Caserta and became seat of the Campi Flegrei Archaeological Museum, as progressive exposure of the most significant topographic artifacts found in this area.