Clambering across slabs of marble, stepping over tumbled columns, wading through banks of wild flowers, finally I found Apollo. There he was – or, at least, part of him. A massive chest rose out of the poppies and daisies and, a few feet away, his thighs and waist. These were the remnants of one of the greatest statues of antiquity – four times life-size, and more than a century older than the Parthenon – lying in the spring sunshine on the Greek island of Delos.

Two and a half thousand years ago, this was a sacred spot, drawing pilgrims from Athens, Rome and all around the Mediterranean. It’s still unique today: a Greek Pompeii, but hundreds of years older than the Roman version. The difference...