The Castle was originally named Castrum Gironis: according to some taken from Girone (Hiero) of Syracuse (the first settlement dating back to the fifth century BC), according to the fortified "round walls" surrounding the trachytic rock island.
In the Middle Ages it was always referred to as Insula Minor to distinguish it from Insula Major (the island of Ischia) which was slowly becoming populated.
It is at this time that the present crypt of the Cathedral of Our Lady of the Assumption dates back to with its precious frescoes.
Its current name originates from the dynasty that most influenced the characteristic appearance of the island: Alfonso I of Aragon in the 15th century AD. The pre-existing Maschio Angiono, constructed with mighty defensive walls, led to the digging of a tunnel in the rock for pedestrian access.
The third generation of the Mattera family now takes care of the Castle, guaranteeing the public access 365 days a year, carrying out any necessary maintenance and restoration work and promoting cultural events which bring it to life.
In fact, the most important work, beyond the restoration, is to keep the Castle alive: it's not simply the exhibition of historical artefacts, but a living being from which an energy pulses that can be used to understand the past and the future: of course, it no longer has the laboured movement of a fortress that defends itself, the tumultuous daily life of 1,800 who work and meet there no longer exists. Today, an unrivalled serenity and peace envelops the Castle, animated by exhibitions of ancient and contemporary art, studied by historians and admired by the thousands of tourists that visit it and commit it to memory.
The art interacts with the Castle and brings it to life; after having held so many roles, the manor takes on the privileged role of interlocutor of all art forms and once again asserts its presence as essential to the balance of the entire "kingdom" that surrounds it.
The lawyer Nicola Ernesto Mattera's initial intuition is still found today in his heirs, the complete enthusiasm and confirmation of the righteousness of an act that, seemingly inexplicable at the time, has ensured the rebirth of a protagonist of the History of the island and the entire Kingdom of Naples.