The Aragonese Castle is a medieval fortress located on a volcanic islet off the eastern coast of the island of Ischia, in the Campania region of Italy. The castle was built in 474 BC by Hiero I of Syracuse and was originally called "Castrum Gironis". In 1438, Alfonso V of Aragon, King of Naples, conquered the island and fortified the castle, which then took its current name.

The castle has a rectangular shape with a perimeter of about 800 meters and stands 113 meters above sea level. It is connected to the main island by a 220-meter-long stone bridge, which was built in 1438. The bridge is about 20 meters high and 3 meters wide and was designed to defend the castle against enemy attacks.

Inside the castle, there are several buildings and structures, including a church, a convent, a prison, a watchtower, and a museum. The church of the Immaculate Conception, located in the center of the castle, was built in the 18th century and features beautiful frescoes and paintings. The convent was built in the 16th century and now serves as a hotel and restaurant.

The castle has been used as a location for several movies and TV shows, including "The Talented Mr. Ripley" and "The Count of Monte Cristo". It is now one of the most popular tourist attractions on the island of Ischia and can be visited all year round.