Walk through the centre of Durrës today and you can step down into a Roman arena that once held twenty thousand people. It is the largest amphitheatre ever built on the Balkan Peninsula, and for most of the last five centuries, the city had no idea it was there.

Construction began under the emperor Trajan in the early second century, when Dyrrachium, as the Romans called it, was one of the most important ports on the Adriatic. Gladiatorial games filled the elliptical bowl until the fourth century, when the old world began to change.

That change arrived first as faith. A Christian chapel was cut into the amphitheatre's vaulted galleries in the second half of the fourth century, its walls covered in frescoes. The arena that had roared with crowds fell quiet, and prayer replaced spectacle.

Two earthquakes, one in the sixth century and one in the tenth, cracked the structure badly. A medieval chapel rose inside the ruins in the thirteenth century, decorated with its own frescoes. Then the Ottoman occupation came, and by the sixteenth century the whole monument had been swallowed by the city growing over it.

It stayed buried for roughly four hundred years. In 1966, archaeologists broke through and found it again. About a third of the site was excavated in the nineteen sixties; the rest followed in the nineteen eighties. What they uncovered included a mosaic chapel, still largely intact, one of the most striking early Christian survivals in the region.

But discovery brought its own dangers. With no conservation effort in place, the exposed stone began to decay. Modern housing crept onto one corner of the arena floor itself. By 2013, Europa Nostra had listed it among the fourteen most endangered heritage sites in Europe.

In 2004, the University of Parma began restoration work. The municipality is now planning to clear the houses that sit inside the ancient walls. The chapel with its mosaics is preserved and open. The amphitheatre functions today as both a museum and the stage for an international film festival each summer.

Twenty thousand voices once filled this bowl for blood sport, then for prayer, then for silence. What buried it was not conquest but simply time and neglect. What is slowly bringing it back is the belated recognition that the Balkans' greatest Roman arena deserves to stand in the open again.