This harmonious structure dominates Piazza del Plebiscito.
It was built to a design by the architect Domenico Fontana and work was begun on the construction in 1600 to coincide with the arrival in Naples of King Philip II.
The building work lasted for more than fifty years; during the final phase the imposing staircase at the main entrance was completed.
The building, as it appears today to the tourist's admiring gaze, owes its present form to a series of transformations, modifications and renovations carried out over the centuries; these have left only the fašade and the "cortile d'onore" (courtyard of honour) unaltered in their original appearance.
the palace was renovated and extended in the first half of the 18th century, and restored by Gaetano Genovese who bought about some substantial neo-classical transformations to the building, following a fire which had damaged it at the time of Ferdinand II (1837).
The last restoration work was carried out in 1994 when the palace hosted the summit of the G7 (the seven most industrialized countries in the world).
The impressive fašade above which stands a clock with a small ribbed campanile, contains two mighty rows of windows, alternating with pilaster strips.
On the ground floor, the original portico was partly modified by Vanvitelli for reasons to do with the building's stability.
There are three entrances on the ground floor.
On the outside, the niches built by Vanvitelli contains statues of Naples' most important sovereigns: Roger the Norman, Frederick II, Charles of Anjou,, Alfonso of Aragon, Charles V, Charles III of Bourbon, Joachim Murat and Vittorio Emanuele II.
In the entrance-hall, near the beautiful 17th century grand staircase by Picchiatti, modified by Genovese, is a bronze door transferred here from the Maschio Angioino; this artistically magnificent work was carried out by Guglielmo Monaco and Pietro di Martino.
Some of the palace wings now house various offices, while the National Library has been housed here since 1804, containing thousands of volumes and an important collection of papyri from Herculaneum.
Of particular interest inside the palace is the Court Theatre, a large hall on the first floor, built by Ferdinando Fuga in 1768. It was here that the royal families gathered for plays, concerts and performances.
Other halls of importance include the Central Hall, the Throne Room (containing the Portrait of Pier Luigi Farnese by Titian), and the Hercules Hall, all of which, along with many others rooms of the Royal Apartment, make up an authentic museum (The Royal Palace Historic Apartment Museum).
The museum abounds in interesting period furniture, porcelain, tapestries, gobelins and paintings from the 17th-18th centuries, mainly by local artists.
Note especially the works by Titian, Guercino, Andrea Vaccaro, Mattia Preti (Prodigal Son), Spagnoletto, Massimo Stanzione and Luca Giordano.
The 17th century Chapel is also worthy of note and clearly shows the interventions carried out by Genovese.