Certosa di San Martino

Stand still for a moment and listen. The traffic of Naples is still there, but up here it sounds far away, like the sea in a shell. Under your feet the paving is cool and worn smooth. The light is different too. It falls on white marble and grey volcanic stone, and it moves across the walls as the clouds pass over the bay below. You have climbed above the city, and the city has gone quiet.

This is the Certosa di San Martino, a former monastery on the top of the Vomero hill. Its neighbour is the star-shaped fortress of Castel Sant'Elmo, which sits just above it. Together they crown the ridge that looks down over the old centre. The word certosa means a charterhouse, a home for Carthusian monks. It is one of the largest religious buildings in southern Italy. Today it is a national museum.

The Carthusians were an unusual order. Saint Bruno founded them in the eleventh century, and their rule asked for silence, solitude and prayer. Each monk lived mostly alone, in his own small house with a garden, and joined the others only for certain services and meals. So imagine this hill centuries ago. The monks looked down on one of the loudest cities in Europe — and lived inside one of its quietest places.

The story begins in the fourteenth century, under the Angevin kings, a French dynasty that ruled Naples at the time. Work started in 1325, sponsored by Charles, Duke of Calabria, the son of King Robert of Anjou. The church was consecrated in 1368, during the reign of Queen Joanna the First. Very little of that Gothic building is easy to see today. Look closely, though, and you can still find pointed arches and older stonework under later layers.

What you mostly see now is the result of a second life. From the late sixteenth century and through the seventeenth century, the monastery was rebuilt in the Baroque style. Baroque means drama: curves, colour, light and movement. The monks were rich by then, and they spent their wealth on art. The leading figure was the architect and sculptor Cosimo Fanzago. His marble work fills the church and the great cloister with inlaid patterns and soft, carved forms.

Walk into the Great Cloister and the space opens. White columns of marble run around a wide square of green. Above the arcades, busts of saints look down into the courtyard. In one corner there is a small enclosed garden, the old monks' cemetery. Along its balustrade, Fanzago placed carved marble skulls. Many visitors walk past them without noticing. They are a quiet reminder, very Carthusian in spirit, that every life here was lived with death in mind.

Now step into the church. The contrast is strong. Outside, the monks lived in silence. Inside, the walls and ceilings are full of colour. Coloured marble covers the floors and chapels in geometric designs. The ceiling of the nave carries frescoes by Giovanni Lanfranco, one of the great painters of the early Baroque. Around the walls you will find paintings by Jusepe de Ribera, a Spanish artist who worked in Naples, and by the local master Massimo Stanzione.

Here is a detail most people miss. In the choir, behind the main altar, hangs a large Nativity by Guido Reni, the celebrated painter from Bologna. He did not finish it. Reni died before the work was complete, and the painting was left as it was. Look at the surface and see if you can tell where the work stops. An unfinished masterpiece in a place built for eternity has its own quiet meaning.

The museum rooms hold something that surprises almost everyone. Naples has a deep tradition of the presepe, the Christmas nativity scene. Here you will find the Cuciniello nativity, named after the collector Michele Cuciniello who gave it to the museum in the nineteenth century. It is not a small crib. It is a whole Neapolitan world in miniature, with shepherds, butchers, musicians, travellers, animals and baskets of tiny food. Every figure has its own face.

The collections also tell the story of the city itself. You will find old maps and views of Naples, including the famous Tavola Strozzi, a fifteenth-century painting that shows the harbour and the city from the sea. There are royal carriages, ceremonial barges, costumes, glass and porcelain. After the monks left in the nineteenth century, when the religious orders were suppressed, these rooms slowly became a museum of Neapolitan life.

But many people come here for one reason above all — the view. Find the terraced gardens and the belvedere. The whole bay spreads out below you. Vesuvius stands to the east, with its two humps. Across the water, on a clear day, you can make out the Sorrento coast and the island of Capri. And directly below, the old city lies in a tight grid of rooftops, domes and bell towers.

Look for one long, straight line that cuts through the old centre. That is Spaccanapoli, a street whose name means "split Naples". It follows the route of a main street from the ancient Greek and Roman city. From up here you see it the way a map does, a clean cut through the mass of buildings. Down there, it is narrow and crowded and full of noise. Up here, it is only a line drawn across the city.

Take a little time before you leave. Sit on a bench in the cloister, or lean on the wall of the garden. Listen to the city below, then to the silence around you. The monks chose this hill so they could stay apart from Naples while keeping it always in sight. As you walk out, look back once at the white columns and the marble skulls. Then follow the city's sounds back down the hill.