Castel dell'Ovo (in Italian, Egg Castle) is a seaside castle located on the former island of Megaride, now a peninsula, on the Gulf of Naples in Italy. The castle's name comes from a legend about the Roman poet Virgil, who had a reputation in medieval times as a great sorcerer and predictor of the future. In the legend, Virgil put a magical egg into the foundations to support the fortifications. Had this egg been broken, the castle would have been destroyed and a series of disastrous events would have involved the city of Naples. The castle is located between the districts of San Ferdinando and Chiaia, opposite the zone of Mergellina.

The Castel dell'Ovo is the oldest standing fortification in Naples. The island of Megaride was where Greek colonists from Cumae founded the original nucleus of the city in the 6th century BC. Its location affords it an excellent view of the Naples waterfront and the surrounding area. In the 1st century BC the Roman patrician Lucius Licinius Lucullus built the magnificent villa Castellum Lucullanum on the site. Fortified by Valentinian III in the mid-5th century, it was the site to which the last western Roman emperor, Romulus Augustulus, was exiled in 476. Eugippius founded a monastery on the site after 492.
The remains of the Roman-era structures and later fortifications were demolished by local residents in the 9th century to prevent their use by Saracen raiders. The first castle on the site was built by the Normans in the 12th century. Roger the Norman, conquering Naples in 1140, made of Castel dell 'Ovo its seat. The importance of the Castel dell'Ovo began to decline when king Charles I of Anjou built a new castle, Castel Nuovo, and moved his court there. Castel dell'Ovo became the seat of the Royal Chamber and of the State Treasury. It also served as a prison.
The current appearance dates from the Aragonese domination (15th century). It was struck by French and Spanish artillery during the Italian Wars; in the Neapolitan Republic of 1799 its guns were used by rebels to deter the philo-Bourbon population of the city.
In the 19th century a small fishing village called Borgo Marinaro, which is still extant, developed around the castle's eastern wall. It is now known for its marina and restaurants. The castle is rectangular in plan, approximately 200 by 45 metres at its widest, with a high bastion overlooking the causeway that connects it to the shore; the causeway is more than 100 metres long and a popular location for newlyweds to have their wedding photos taken. Inside the castle walls are several buildings that are often used for exhibitions and other special events. Behind the castle there is a long promontory once probably used as a docking area. A large round tower stands outside the castle walls to the southeast.:,,,,ReferencesSources:I castelli di Napoli. Elio De Rosa. 1992.