Its name derives from an ancient legend according to which the Latin poet Virgil hid an egg in the dungeons of the building to keep the entire fortress standing. Its breaking would have caused not only the collapse of the castle, but also a series of disastrous catastrophes to the cityà of Naples.
During the fourteenth century, at the time of Joan I, the castle underwent a severe damage due to the partial collapse of the arch on which it was built; it rested and, in order to prevent panic among the population for the alleged future catastrophes that would affect the city, the queen had to swear that she had replaced the egg.
