As the train heads south from Rome, you slip across that invisible line which marks the start of the Italian South - a region known in Italian as the mezzogiorno. Rome is ambiguous, but Naples is assertively part of southern Italy. The principal city of the Campania region, Naples is the jumping-off point for excursions to Vesuvius, Pompeii and the Sorrento Peninsula. The celebrated coastal villages of Positano, Amalfi and Ravello are all within easy reach. So too are the islands of Capri and Ischia.

Make time, too, for Naples itself (called Napoli in Italian). It’s a complex, fascinating city – one which has many different moods. Wander the lively back alleys of the Old Town (called the centro storico) and then cut down to the laid-back waterfront district for sea views and seafood.

Long-distance trains from northern Italy all arrive at the main station, Napoli Centrale. It’s on Piazza Garibaldi just east of the city centre. Centrale is also the departure point for trains to Calabria and Sicily. Local trains to Sorrento do not serve Centrale; they stop instead at Piazza Garibaldi station, which is just two minutes on foot from Centrale - and actually underneath the main-line station.

Since late 2018, a number of high-speed trains heading north from Naples also serve the remarkable new station at Afragola in the city's northern suburbs. It's a stylish statement by Zaha Hadid, built as part of a wider urban renewal programme in a part of Naples noted for its involvement in Camorra gang wars.

Naples has no international rail services. But it has a superb range of high-speed trains to cities in northern Italy. There are hourly departures to Milan, with the fastest trains taking just 4 hrs 15 mins. Rome is just over an hour away. But journeys to the south are much slower. The fastest trains from Naples to Palermo (in Sicily) take over nine hours. The journey to Taranto (through the hills of Basilicata) takes over four hours.