Hexamilion Wall

Run your hand along the stone here and you will feel two textures at once. Rough mortar and rubble sit beside smooth, squared blocks that were cut for a very different purpose. Listen, and you may hear traffic on the main road, the wind moving through pine and scrub, and somewhere nearby the sea. You are standing on the narrow neck of land that ties the Peloponnese to the rest of Greece. For roughly a thousand years, people tried to close this neck with a wall.

The name tells you its size. Hexamilion is Greek for "six miles", and that was roughly the distance it had to cover. The wall ran across the Isthmus of Corinth, from the Gulf of Corinth on the west to the Saronic Gulf on the east. Look at a map and the logic is clear. The Peloponnese is almost an island. Seal this strip, and an army coming from the north has to find a way around by sea.

The idea is much older than the wall in front of you. In 480 BCE, when the Persian king Xerxes marched into Greece, the Greek historian Herodotus tells us that the Peloponnesians hurried to build a barrier across this isthmus. The Persians were stopped at sea, at Salamis, before that test came. But the instinct stayed in the region's memory. When danger came from the north, people looked at this strip of land and thought about walls.

The Hexamilion itself is a Roman work from the late Roman Empire, the period scholars often call early Byzantine. It is usually dated to the early fifth century, and many historians link it to the reign of the emperor Theodosius the Second. This was a frightening age for Greece. Only a few years earlier, Gothic forces under Alaric had swept through the region. A strong line across the isthmus promised that the south, at least, could be held.

Now look closely at how the wall was made. The builders used a thick core of rubble and mortar, faced on both sides with cut stone. Towers stood at regular intervals along its length, and archaeologists have counted well over a hundred of them. The wall was several metres thick in places. It was not elegant work. It was fast, heavy and practical — the kind of building you make when you expect trouble soon.

Here is the first detail most visitors miss. Many of those smooth, squared blocks were not quarried for the wall at all. Near the village of Isthmia stood the Sanctuary of Poseidon, home of the Isthmian Games, one of the great athletic festivals of ancient Greece. By the fifth century the old temples were falling into disuse. The wall builders took their stones. Carved pieces, inscribed blocks and parts of buildings went straight into the defences.

So when you look at a neat block set into rough rubble, you may be looking at a fragment of a pagan sanctuary. It was reused by a Christian empire to protect itself. Archaeologists call this reused material spolia. Excavations at Isthmia, carried out over many decades by American teams, have recovered many such pieces from the wall and its fortress. Some are now in the small archaeological museum nearby.

That fortress is the second surprise. The Hexamilion was not only a single line of stone. At Isthmia it joined a large walled fortress, with gates and towers, built against the line of the wall. Soldiers could gather there, store supplies and move along the defences. Traces of its walls and its gateways still survive near the old sanctuary. Standing there, you can picture a garrison watching the road from the north.

Walls need constant care, and this one was repaired many times. The emperor Justinian, in the sixth century, is recorded as strengthening the defences of the isthmus. Then the centuries passed, and the wall fell into ruin. Its great second life came much later, when the Byzantine Empire was small and under pressure from the rising Ottoman state. Suddenly this old line mattered again.

In 1415 the emperor Manuel the Second Palaiologos came here in person to rebuild the wall. Sources describe the work as remarkably fast, done in a matter of weeks. Later, in the 1440s, Constantine Palaiologos, who ruled the Peloponnese as despot and later became the last Byzantine emperor, repaired it again. For a short time the old Roman wall was the front line of a dying empire.

But the world had changed. In 1446 the Ottoman sultan Murad the Second brought his army to the isthmus. He also brought cannon. After a short siege, the wall was broken and its defenders overwhelmed. A defence designed against swords, ladders and siege engines could not stand against gunpowder artillery. The Venetians made one more attempt to restore the line in the 1460s, but it did not last.

Today the wall is easy to overlook. Sections run through fields, beside roads and between houses, sometimes as tall stretches of masonry, sometimes as a low ridge under the grass. The modern Corinth Canal, cut through the isthmus in the late nineteenth century, now does what the wall only tried to do. It truly separates the Peloponnese from the mainland, with a channel of water instead of stone.

Before you leave, look along the line of the wall and follow it with your eyes toward the sea. Notice the mix of stone again — rough rubble, smooth reused blocks, patches of later repair. Each layer belongs to a different moment of fear and hope. Then listen once more to the wind and the traffic. People still cross this narrow land every day, mostly without thinking about the wall beside them.