The ancient castles built to defend the city and kingdom of Naples, all of which still conserve the history and legends of a much-contested European capital. Castles and fortresses: essential architecture for any capital which intends to avoid attack and defend its borders, and Naples, for centuries an unassailable capital, has not one, but four. The proliferation of strongholds was, in part, the result of the need to control the various access points to the city, and in part to satisfy the vanity of its frequently changing rulers. From the Normans to the Anjou, Aragons and Svevi: each power left its mark in the form of magnificent fortifications.

The oldest of Naples' castles is the Castel Capuano, erected by the Normans in the latter half of the 12th century. An unassailable fortress, Castel Capuano was built to defend Porta Capuana, the main entrance to the city for all those not traveling by boat. The castle was used as royal residence by the Normans and Svevi, and in particular by Frederick the II who, in 1231 initiated the first major enlargement of the edifice. Castel Capuano provided the sumptuous venue for wonderfully opulent royal weddings, but was also the scene of crimes, such as the 1432 assassination of Ser Gianni Caracciolo, commissioned by none other than his former lover, Queen Joan the 2nd. With the arrival of the viceroy, in the 16th century, the castle was completely renovated and transformed into law courts and even today continues to host the official inauguration of the Judicial year.

Naples' second oldest castle is Castel dell'Ovo, built by the Normans as a strategic watchtower overlooking the sea. Castel dell'Ovo stands on the islet of Megaride, which is linked by a bridge to via Partenope, the street which now functions as Naples' most fashionable seafront promenade and where the majority of the city's luxury hotels are located. The castle's position is not only strategic, but symbolic too. Legend has it that it was here that the body of the mermaid, Parthenope, was cast ashore. Another tale is that of the egg. The Ancient Roman patrician Lucullo decided to build a massive villa back in 1BC. Apparently, in the secret underground tunnels of this residence, the poet Virgil hid a magic egg to which the castle owes both its name and its fortunes. One more legend tells of how it was here that the Queens Giovanna I and II used to meet their lovers, young men who were all subsequently "disposed of" via the edifice's hidden drop wells. During the siege of 1503, Castel dell'Ovo was seriously damaged and was later rebuilt, as we now see it, by the viceroy.

The Maschio Angioino is another of Naples' best-known buildings. In 1266, when he was crowned King of Naples, Charles I of Anjou decided to construct a new castle or "Castello Nuovo" (as the Maschio Angioino is still often referred to), which would guard both the Royal Palace and the sea. The façade of the castle is orientated towards the Piazza Municipo, and sports a magnificent triumphal arch, which Alfonso of Aragon had built to mark his arrival in the city. Today the castle houses the Naples Civic Museum. The visit to the museum includes a tour of the Palatina Chapel which, unlike the majority of the castle's rooms, has been left almost unaltered by the passage of time. The Barons' Hall has a decidedly Spanish appearance, with an incredibly high octagonal vault. The hall's name makes reference to the "Barons conspiracy" of 1486. When Ferdinand of Aragon discovered their plans to overthrow him, he invited his Barons to the castle, on the pretext of his niece's wedding, and promptly had them arrested and sentenced to death.

More than any other castle in Naples, Castel Sant'Elmo is able to control the entire city, thanks to its strategic position on the hill of Vomero. Built on the site of an ancient Norman watchtower, Castel Sant'Elmo has always been used for military purposes and has even functioned as a prison, where the writer Tommaso Campanella was incarcerated. Today the castle attracts visitors with its stunning 16th century architecture and panoramic terraces from where wonderfully romantic views of Naples and the bay can be seen.