Most of the current "New Castle" dates from the 15th century, when the Aragonese monarch Alfonso V carried out a number of renovations to the original building, including its white marble triumphal arch. At the end of the 1600s, Naples was annexed by Spain and the castle was downgraded to military fortress, but Charles III moved back in as king of Naples in 1734 and restored it to its former glory. Today, visitors can tour the castle's halls and courtyard, 14th-century Palatine Chapel decorated with fragments of frescoes from the Giotto school, and Museo Civico.
This castle is best visited with a tour guide as part of a Naples Segway tour or walking tour that includes visits to other landmarks such as the Castel dell'Ovo and Royal Palace. Alternatively, a visit to Castel Nuovo can be combined with a Neapolitan food tour or an archaeological tour of sites in Naples and nearby Pompeii.