Hadrumetum

Stand still for a moment and listen. Behind you, scooters buzz through the streets of modern Sousse. In front of you, the sea moves against the shore, the same slow rhythm it has kept for thousands of years. Under the pavement, the shops and the apartment blocks, there is another city. It is buried, layer on layer, in the warm sandy earth. That city was called Hadrumetum, and you are standing on top of it.

This is one of the oldest settlements on the coast of Tunisia. Phoenician sailors founded it. They were traders from the eastern Mediterranean, the region of modern Lebanon. They built harbours along this shore for their ships. Ancient tradition says Hadrumetum was older than Carthage, its far more famous neighbour to the north. That claim is hard to prove. But it tells you how deep the roots of this place go. Long before Rome, long before Islam, ships came here to trade.

Here is the first surprise. Most of Hadrumetum is not a ruin you can walk through. There is no single gate, no fenced field of columns. The ancient city lies beneath modern Sousse itself. People have lived on this exact spot without a break for close to three thousand years. Each generation built on top of the last. So when you look for Hadrumetum, you look in fragments — a stretch of old wall, a reused stone, a mosaic in a museum, a passage underground.

The city entered the great wars of the ancient world. During the long struggle between Carthage and Rome, Hadrumetum stood on the Carthaginian side. Hannibal, the general who famously crossed the Alps with elephants, used this coast as a base near the end of the Second Punic War. Shortly after, in 202 BC, he lost the decisive battle of Zama. Hadrumetum survived that defeat. Later, in the final war against Carthage, the city took the side of Rome. That choice was rewarded. Rome left it standing when Carthage burned.

Roman power changed the face of the city. Later, Julius Caesar fought his civil war campaign in Africa along this coastline, and Hadrumetum was caught up in it. Under the emperor Trajan, in the early second century, the city became a Roman colony. That was a high status, close to that of Rome itself. Its official name was long and proud. One part of it, Frugifera, means fruitful. The title fits. This coast was rich in olive oil and grain, and much of it was shipped across the sea.

Here is a detail many visitors miss. Ancient writers say that a Roman emperor was born here. Clodius Albinus was a governor and general who claimed the throne in the late second century. His bid for power failed, and he died in battle in Gaul. Still, a man from this African harbour once reached for the highest office in the Roman world. It shows how fully this province had become part of the empire's heart.

Wealth in Roman Africa often showed itself on the floor. The rich families of Hadrumetum laid mosaics in their homes — pictures made from thousands of tiny cubes of coloured stone. Sea gods, fish, hunting scenes and harvests appear again and again. The most celebrated mosaic from this city does not stay in Sousse. It shows the poet Virgil seated between two Muses, the goddesses of the arts. It was found here in the 1890s and now hangs in the Bardo Museum in Tunis. It is one of the very few ancient portraits believed to show the poet.

Many other mosaics from Hadrumetum stayed closer to home. They are displayed in the Sousse Archaeological Museum, inside the old kasbah at the top of the medina. The kasbah is a fortress on the highest point of the old town. Inside, the floors from Roman villas now cover the walls. You can stand close and see the cubes one by one. Then step back, and the picture comes together. The colours are mostly earthy — ochre, cream, deep red, slate blue, all from natural stone.

Now for the second surprise, and it is underground. Beneath the western side of the city lie the Catacombs of Sousse. These are long tunnels cut into soft rock by the early Christian community. They used them as burial places from around the third century onward. The passages run for long distances, with rows of graves carved into the walls. Thousands of people were laid to rest here. Visitors can enter part of the network. The air is cool, the light is low, and the walls are close on either side.

The empire changed, and so did the city's name. In the late Roman period, Hadrumetum became the capital of a province called Byzacena. Then the Vandals arrived. They were a Germanic people who crossed from Spain and took Roman Africa in the fifth century. They renamed the city after their own king. In the sixth century, the Byzantine Empire, the eastern half of the Roman world, won the region back. The city received a new name again, this time honouring the emperor Justinian.

In the seventh century, Arab armies brought Islam to North Africa. The old harbour gained the name it still carries — Sousse. In the ninth century, the city's new rulers built the great fortified monastery called the Ribat, and the Great Mosque nearby. Builders of that age often reused older materials. As you walk the medina, keep an eye on the stonework. A column, a block or a carved fragment may be far older than the wall that holds it.

That is the real way to experience Hadrumetum. Think of it as a city you read rather than a city you visit. Start in the museum, with its mosaics and grave stones. Walk down through the medina, which UNESCO lists as a World Heritage Site. Visit the cool tunnels of the catacombs. Then come back to the waterfront. The modern port sits close to where Phoenician and Roman ships once tied up. The trade routes changed. The shoreline is still the reason the city is here.

So take one last look around you. The traffic, the café chairs, the call to prayer from a minaret — all of this rests on the old city. Merchants, soldiers, poets' admirers and early Christians walked this same ground. As you leave, look down at the pavement now and then. You are walking over Hadrumetum, quietly, the way the people of Sousse do every day.