Castel Sant'Elmo

From the Vomero hill above Naples, at 250 metres above the bay, the view is the one that makes people understand why this city has been fought over continuously for 2,500 years. The entire arc of the Gulf of Naples spreads below: Vesuvius to the east, the islands of Capri and Ischia to the south, Castel dell'Ovo on its promontory to the left, the dense fabric of the historic centre directly underneath. Castel Sant'Elmo was built on this ridge for one reason — whoever held this height controlled Naples. For four centuries, it was the key to the city.

The first castle on the Vomero hill was built by the Angevin King Robert of Naples in 1329. Robert was one of the most sophisticated rulers of medieval Italy, his court attracting Petrarch, Boccaccio and Giotto. His castle, known as the Belforte, was rectangular with four towers, built in the local yellow tuff stone that gives Neapolitan architecture its warm colour. This first structure suited the medieval city well enough, but it was wholly inadequate for the changed conditions of 16th-century warfare, when artillery had rendered vertical walls obsolete almost overnight.

The Viceroyalty of Naples was the most important Spanish possession in Italy, and the Spanish crown needed to defend it against French attack and internal rebellion. Pedro Luis de Escrivà — a military engineer who had already worked on the fortifications of Ibiza and would later design defences at L'Aquila — was commissioned to rebuild the Belforte entirely. He demolished the Angevin structure and replaced it with a six-pointed star fortress: six triangular bastions projecting from a hexagonal central body, each positioned to provide flanking fire along the adjacent curtain walls. The geometry was simultaneously military and mathematical — no attacker could approach any section of wall without being exposed to fire from at least two directions at once.

The castle's history after its Spanish rebuilding is largely a history of imprisonment and repression. The philosopher and astronomer Giordano Bruno was held here in the late 16th century before his trial and execution in Rome — a man whose cosmological speculations had outpaced what the Church of his time could tolerate. The Neapolitan Parthenopean Republic of 1799, a French-backed revolutionary government that briefly overthrew the Bourbon monarchy, fell when Cardinal Ruffo's army retook the city; its leaders were executed in the Piazza del Mercato below, and the castle reverted to Bourbon control. During the Second World War the castle held Italian anti-fascist partisans. The walls carry, in compressed sediment, four centuries of political struggle.

Today the castle functions primarily as a cultural venue and museum, its inner parade ground hosting outdoor exhibitions in summer. But the primary reason to come remains the view. The 360-degree panorama from the ramparts is among the finest urban views in Europe, the kind that forces a recalibration of scale. Naples from this height reveals itself as an extraordinarily dense city, packed into a coastal plain between the volcano and the sea with no natural room to expand. The view also explains the logic of the castle's placement: any ship approaching from the sea, any army approaching from the mainland, would have been visible from here hours before arrival.

Directly adjacent to Castel Sant'Elmo, on the same Vomero hilltop, stands the Certosa di San Martino, a Carthusian monastery founded in 1325 and rebuilt in the 17th century, now one of the finest Baroque interiors in Naples. The monastery church contains works by Ribera, Luca Giordano and Giovanni Lanfranco. The Certosa and the castle are effectively one complex and reward being visited together; a combined ticket is available for both.