"Napoli is like a lasagne. It's full of layers and every time we dig down, we find another slice," says Brunella Uva, our Neapolitan guide, nodding to the building site near the cruise terminal.

She reveals that work to extend the city's Metro system led to the discovery of an earlier port, established by Greek sailors almost 3000 years ago. A glass-floored viewing window overlooking the relics is being planned, adding to the cornucopia of cultural treasures that wow visitors to Napoli (or Naples) and its volcano-riddled surrounds.