Isca Augusta

Stand still for a moment and feel the ground under your feet. It is soft grass, and it slopes gently up toward the grassy banks of the amphitheatre. Somewhere nearby, a blackbird is probably singing, and you may hear a dog walker on the lane. It feels like an ordinary Welsh village green. But under this turf, and under the houses around you, lie the streets of one of the great military bases of the Roman Empire.

This is Isca Augusta, the Roman legionary fortress at Caerleon. The Romans built it in the 70s of the first century, as they pushed west into the hills of South Wales. The name comes from the river. Isca is a Latin form of an old British word for water, and the river beside you is still called the Usk. Even the village name carries the memory. Caerleon comes from Welsh words that mean, roughly, fortress of the legion.

That legion was the Second Augustan Legion, one of only three permanent legions stationed in Britain. A legion at full strength held several thousand soldiers. These were professional infantry, Roman citizens, trained to march, fight, dig and build. Most of them did not come from Wales at all. They came from across the empire. For them, this damp green valley was a long way from home. It was also their base for generations.

The fortress followed a standard Roman plan, a rectangle with rounded corners, like a playing card. A wall and a ditch ran around the outside. Inside, straight streets divided the space into barracks, granaries, workshops, a hospital, a headquarters building and the commander's house. At first the soldiers built in timber. Later they rebuilt the defences and many buildings in stone. Much of that stone was carried away in later centuries, and it still sits inside local walls and cottages.

Now look at the amphitheatre itself. It is an oval arena sunk into the ground, with grassy banks rising around it. Those banks once held wooden seating for several thousand spectators. Archaeologists describe it as the most complete Roman amphitheatre in Britain. It stood just outside the fortress walls. Here the soldiers watched gladiators, wild animal shows and, very likely, military drills and parades. The space served as a training ground as much as a theatre.

Here is the first surprise. For centuries, nobody here knew this was Roman. Before excavation, the arena was a grassy hollow, and local people called it King Arthur's Round Table. The idea came from medieval writers. In the twelfth century, Geoffrey of Monmouth placed King Arthur's court at Caerleon, which he called the City of the Legions. The mighty ruins around the village made the story easy to believe. So legend grew up over the real Roman remains.

The truth came out in the 1920s. The archaeologist Mortimer Wheeler, with his wife Tessa Wheeler, led a major excavation of the arena. A national newspaper helped to pay for the dig, partly because the Arthurian story attracted readers. The digging showed that the Round Table was a Roman amphitheatre. Walk slowly around the arena wall. You can still see the entrances where performers came in, and small side chambers set into the wall.

The Arthurian link did not disappear, though. In the nineteenth century, the poet Alfred Tennyson came to Caerleon while he worked on his Arthurian poems, the Idylls of the King. He wrote about the river Usk flowing past the old town. So this place carries two stories at once. One is the documented story of the Roman army. The other is the long life of a legend that grew up in its ruins.

A short walk away is the Prysg Field. Here you can see the stone foundations of Roman barrack blocks laid out in the grass. These are a rare sight. Very few legionary barracks anywhere in Europe are on open display like this. Each long block housed a century, a unit of about eighty men. The soldiers shared small rooms in pairs, with one room for sleeping and one for kit. A larger suite at the end belonged to their centurion.

Nearby you will also find a stretch of the fortress wall and the low remains of buildings in the corner of the base. Try to imagine the noise. Hobnailed boots on gravel. Cooking smoke. Men complaining about the cold and the rain. The fortress was not only a war machine. It was a community, with traders, families and craftspeople living around its walls in a settlement that grew up outside the gates.

In the village, a modern building covers the fortress baths. Inside, walkways let you look down on part of a huge Roman bath complex, including the open-air swimming pool. For soldiers, the baths were a gym, a social club and a little piece of Mediterranean life. Here comes the second surprise. Excavators searched the drains and found dozens of small engraved gemstones. They had fallen out of bathers' rings, probably loosened in the warm water.

The drains held smaller and more human losses too. Archaeologists found children's milk teeth there. That small detail tells us that children came to these baths, not only soldiers. Many of the finds from Caerleon are now in the National Roman Legion Museum in the village. There you can see armour, tombstones, and objects from daily life. They help you picture the people who lived and served inside these walls.

In time, the legion's role changed. Parts of the Second Augustan Legion worked on major projects in the north of Britain, including the building of Hadrian's Wall. By the later Roman period, the fortress was no longer the busy base it had once been. Its stone slowly became part of the village that grew over it. The Roman street plan still shapes some of the lanes you walk along today.

Before you leave, stand at the edge of the arena again. Look at the grassy banks, the quiet houses, the church tower above the rooftops. Nearly two thousand years ago, this same hollow echoed with the shouts of a crowd. Now it holds birdsong and the sound of children playing. As you walk back through the village, notice the old stones set into garden walls. Some of them may once have been part of Rome.