The island of Nisida is the smallest in the Gulf of Naples, a small crescent-shaped volcanic rock located in the eastern part of the Sea of Pozzuoli. Belonging to the Phlegraean Islands archipelago, Nisida is located at the extreme tip of the Posillipo hill, in an area called Coroglio. Despite its beauty, this mysterious and green island is inaccessible as it hosts the Naples Juvenile Penitentiary, while its small port located towards the Coroglio area was restricted, as it was used by NATO until the transfer of military activities. Like the fantastic island described in the famous song by Edoardo Bennato, Nisida seems like an unattainable and mysterious place, which has inspired and continues to inspire the imagination of artists and poets and can usually only be admired from afar, especially from the heights of the magnificent Parco Virgiliano in Posillipo. Occasional guided tours are allowed by authorized cultural associations.

Nisida has a millennia-old history and ancient legends that make it even more fascinating. Its name derives from the Greek "Nesís", meaning island, and it has been identified as "the island of goats" mentioned in Homer's Odyssey. According to a local legend, the island would have been the place where the young Posillipo fell desperately in love with the beautiful and wicked Nisida, without ever being reciprocated. After months and years of suffering, Posillipo decided to end his life by throwing himself into the sea, but Fate transformed him into a promontory on the Gulf of Naples, while Nisida became the little island in front. The island of Nisida is a volcanic island, part of the Phlegraean Fields system. Although once considered an island, since 1936 it has been connected to the mainland by a drivable pier. The volcanic origin of the island dates back over 6,000 years ago, when an important eruption occurred causing the emergence of the site. Nisida also has a history dating back to Roman times, as demonstrated by the ancient man-made structures found on its seabed, currently submerged. The castle of the same name, originally built in the late Angevin period and later adapted in the 17th century, stands on the island and in the past was used as a quarantine station during the 1626 plague epidemic and as a political prison during the Bourbon period. Currently, the castle houses the juvenile detention center, but within the institute young detainees participate in a training and reintegration project called "the factory of arts", which produces ceramic objects and other items. Therefore, Nisida carries with it the history and changes that have shaped its existence. From the original volcanic island separated from the mainland, it has become an island connected to the land and has undergone various transformations, from fortifications against pirates to political prisons, up to its current destination as a juvenile detention center. Despite this, Nisida continues to be a fascinating place full of history that deserves greater visibility.