Called nuovo (new) to distinguish it from the older Castel dell'Ovo, this castle is better known locally as the Maschio Angioino (Angevin stronghold). It was built in 1279 by Charles of Anjou and used by subsequent Angevin monarchs as a royal residence and fortress. It also became a centre of arts and literature, attracting such illustrious characters as Petrarch, Boccaccio (some of the best tales of the Decameron are set in Naples) and Giotto, who, in around 1330, frescoed the main hall and chapel.
Precious little of Giotto's work remains. The castle's current appearance is the result of radical alterations that were carried out by the Aragonese monarchs in the mid 15th century; the splendid triumphal arch was added for the entry into the city of Alfonso I 'the Magnanimous' of Aragon in 1443, a scene that is depicted in the relief above the portal. Subsequent changes to the interior decoration of the palace occurred during the reign of the Viceroy.
The castle has housed Naples' museo civico since 1992, with access via an internal courtyard after the ticket office. In the far left-hand corner of the enclosure, an area of glass flooring enables visitors to examine various ancient finds. These include the foundations and cemetery areas (replete with skeletons) of a convent that long pre-dates the castle itself. An adjacent staircase leads to the Sala dei Baroni, named after the mutinous barons arrested here while conspiring against King Ferrante in 1486. Giotto's frescoes have disappeared; not so the unusual, umbrella-vaulted ceiling that now hovers dramatically over Naples City Council meetings.
The plain yet elegant Cappella Palatina, also shorn of its Giottos (bar tiny traces in the embrasure of the right-hand apsidal window), is the only section that remains from the Angevin period.
The museo civico is housed on two floors. The first contains paintings from the 15th through to the 18th century, with much local colour; the second 19th- and 20th-century works by Neopolitan artists. There's also a fine bronze door, commissioned in 1475 by the Aragonese to commemorate their victory over the Angevins (the embedded cannonball probably dates from a sea battle off Genoa in 1495, when the door was being shipped to France). Don't miss the views from the fortress towers, accessible by lifts.