Basilica of Sant'Apollinare in Classe

Walk through the doors and the light changes. Outside, the air smells of cut grass and warm brick. Inside, the floor is cool, the space is wide and quiet, and your eyes go straight to the far end. There, at the top of a short flight of steps, the apse glows green and gold. It feels like a meadow painted on the inside of a shell. Take a moment before you walk forward. Many visitors hurry. This place rewards the slow ones.

You are standing in the Basilica of Sant'Apollinare in Classe, a few kilometres south of Ravenna's old centre. The church was consecrated in the year 549, in the middle of the sixth century. That makes it roughly fourteen and a half centuries old. Archbishop Maximian presided over the consecration. The money came largely from a wealthy local banker named Julianus Argentarius, a man who also helped fund other great churches in Ravenna during the same years.

The word Classe matters here. It comes from the Latin word for fleet. In Roman times this flat land was a busy harbour, one of the main bases of the imperial navy, founded under the emperor Augustus. Ships, sailors, warehouses and merchants filled the area. Today you see fields and pine trees instead. Over the centuries the river mouths filled with silt, the coastline moved east, and the sea pulled away. The church stayed. The port did not.

Now look at the building itself. From outside it is plain red brick, almost modest. This is typical of the early Christian churches of Ravenna. The builders saved the richness for the interior, where believers would see it. The plan is a basilica, which means a long central hall, called the nave, with lower side aisles and a rounded apse at the end. It is a Roman public building shape, adapted for Christian worship.

Next to the church stands the round bell tower. It is a later addition, built several centuries after the basilica, probably around the tenth or eleventh century. Round towers like this one are a local tradition in the Ravenna area. Notice how the windows change as the tower rises. Near the bottom there are single narrow openings. Higher up they become double, then triple. This makes the tower lighter as it goes up, both in weight and in look.

Back inside, walk slowly down the nave. Two rows of columns line your way. They are made of grey-veined marble from the island of Proconnesus, in the Sea of Marmara, near Constantinople. The marble was a famous export of the eastern empire. Look at the capitals at the top of each column. Their carved acanthus leaves look as if wind is moving through them. These columns travelled by sea to this harbour, which was then the gateway of Byzantine Italy.

Here is something many visitors do not notice. The long walls above the columns are bare. They were not always like this. These walls once carried mosaics too. According to well-known accounts, in the fifteenth century the lord of nearby Rimini, Sigismondo Malatesta, took marble and decorative stone from this church for his own new temple in Rimini. Whatever the full story, the empty walls today make the surviving apse stand out even more.

Now come closer to the apse. In the centre stands a slim figure in white and purple robes, with his arms raised in prayer. This is Saint Apollinaris, honoured as the first bishop of Ravenna. Tradition says he came from Antioch and preached here in the early Christian period. On each side of him walk white sheep, twelve in total. They represent his community of believers. Around them grow trees, rocks, flowers and small birds.

Look above the saint. A great blue disc, filled with stars, holds a jewelled cross. At the very centre of the cross is a tiny face of Christ. This is one of the surprises of the church. The scene shows the Transfiguration, the Gospel moment when Christ appeared in light to three apostles on a mountain. The artists did not paint people for the apostles. Instead, three sheep look up at the cross. The figures of Moses and Elijah float on either side, and the hand of God appears from the clouds above.

This kind of symbolic language was normal for its time. The mosaic does not try to show a real landscape. It shows ideas. Gold background means heaven. Green fields mean paradise. The cross in the starry sky joins the earth and the heavens. If you stand still, you may notice how the small glass and stone pieces, called tesserae, are set at slightly different angles. They catch the light in different ways as the day moves on.

On the lower side walls of the apse there are two more panels, added later. One shows an emperor granting privileges to the church of Ravenna. The other shows Old Testament scenes of sacrifice, with figures such as Abel and Abraham at an altar. Between the windows you can also see portraits of bishops of Ravenna. Together they connect the church to political power and to a long line of local religious leaders.

As you walk back along the aisles, look at the heavy stone coffins along the walls. These are sarcophagi of archbishops of Ravenna, carved over several centuries. Some show crosses, lambs, peacocks and vines. The peacock was an early Christian symbol of eternal life. In 1996, this church became part of a UNESCO World Heritage site, together with seven other early Christian monuments of Ravenna, including the mausoleums and baptisteries of the city.

Before you leave, stand once more near the entrance and look back toward the apse. From here the green meadow seems to float at the end of the long, pale hall. Outside, the land is flat and quiet, and the old harbour is gone. But the saint still stands with his arms raised, and his sheep still walk through the gold. As you step back into the daylight, listen for the birds in the trees around you. The painted ones inside have kept singing a little longer.