Not many people know it, but hidden behind St Peter's Basilica, beneath the guesthouse where Pope Francis lives, flanked by statues of saints, is the world's smallest national railway.
Opened in 1934, the Vatican Railway is a 0.79-mile stretch of track that connects the State's only station with one just outside the Vatican walls, in Rome. It was once used to transport Popes – dead and alive – but in recent years it has, thanks to the papal plane, been relegated to freight runs, bringing goods from Italy into the Vatican.
Now, for the first time in its history, the railway has opened to tourists. Since September, as part of an initiative by Pope Francis, the train now connects the Vatican's tourist hotspots in Rome to the papal summer palace in Castel Gandolfo, beside the sea, and the swathes of gardens and farmland that surround it.
The full-day ticket also includes free entry to the Vatican Museums and Gardens in Rome. So, on the day of the inaugural train journey, I arrived early at the entrance to the Vatican. The 90 minutes between collecting my audioguide and novelty steam-train sticker and the start of the next stage of the tour was emphatically not enough time to see the whole Vatican Museum. So, I headed for the quieter galleries to avoid tour groups and being corralled by staff into the Sistine Chapel.
The map provided with the tour recommends a wildly optimistic route around the main galleries, but it also suggests some alternatives. Take them. At 8.30am the Egyptian Galleries, with rooms of sarcophagi and a reconstructed second century villa, were almost deserted.
The Vatican Gardens, where the self-guided tour of the museums ends and an hour-long, chaperoned walk begins, were revelatory. Hidden behind the Vatican's tall walls are narrow paths that wind through woods, between fountains and grottos. Its 57 acres are another art gallery, of sorts, that culminates with the magnificent Fontana dell'Aquilone (Eagle Fountain), a grotto of riven rocks and gushing water. Beyond it the hill drops away and the railway station – a smart, white building flanked by tall columns – comes into view.
My heart sank a little when I saw the train. I had read that visitors on the press preview had been transported by a magnificent refurbished steam train, but those, like me, on the regular trips must apparently make do with a borrowed Trenitalia engine – the sort of unremarkable workhorse that runs across the Italian national railway.
Our train pulled away from St Peter's, through an imposing arch usually sealed by an iron gate, and across the viaduct that leads to the Roman side of the Vatican walls. Its 300m, three-minute journey ended unremarkably, by pulling into San Pietro, the closest main- line station.
From there, it rolled out across the Italian countryside, bisecting fields and villages until it reached Lake Albano, positioned in a crater in the Alban hills and overlooked by the Pope's summer residence and the town of Castel Gandolfo.
The tour then continues by train and minibus to the neighbouring town of Albano Laziale for a trip around the palace gardens. During the winter, or if you're more interested in art and architecture, you can disembark at Castel Gandolfo and join the tour of the Papal Apartments instead. With a few wartime exceptions, Francis is the first Pope since the 17th century not to retreat here during the hot, Roman summer – a decision that has had a major impact on the tourist economy in Castel Gandolfo. Summer visitors once flocked to mass in the courtyard and to receive a Papal blessing – now they can lean over that same balcony and look down on to the empty square below.
In the Summer Palace gardens, the autumn sun shone on tree-lined boulevards and across the many fountains. It was easy to understand why Pope John Paul II spent five years here in total, and why the Emeritus Pope Benedict XVI retreated here after his shock resignation in 2013.
The tour of the gardens – aboard a motorised tourist train – departs from the helipad where he landed, climbing through olive groves to formal gardens. The land's history juts out between the pine groves: the garden sprang up around the ruins of a palace built by the first century Emperor Domitian, and a ruined wall of that villa crowns the garden, falling away on one side into the remains of his crumbling amphitheatre.
With three hours' free time between the end of the tour and the return train, I headed away from the market square, fringed with espresso bars, to Le Bioalchimie for an organic, vegetarian lunch big on regional produce. In this cosy, rustic restaurant everything has been made from scratch – including the furniture.
The return train pulled into Rome's San Pietro station soon after 6pm. As evening approaches each Saturday, the Holy See, which on this tour offers unprecedented insight into the Papal lifestyle, locks the lid on its secrets.
Now empty, the train returns to its sidings in the hillside behind St Peter's and the iron gate shuts tight for another week.
Many airlines serve Rome’s main airport, Fiumicino, including Jet2 (0800 408 1350; jet2.com) from Belfast, Glasgow, Leeds/Bradford, Manchester and Newcastle; Alitalia (0871 424 1424; alitalia.com) from Heathrow and London City; Monarch (0333 003 0100; monarch.co.uk) from Birmingham and Luton; easyJet (0905 821 9000; easyjet.com) from Bristol and Gatwick; British Airways (0844 493 0758; ba.com) from Heathrow and Gatwick; Norwegian (0843 3780 888; norwegian.com)and Vueling (0906 754 7541; vueling.com) from Gatwick.
Residenza Sistina (00 39 392 808 0668; residenzasistina.com). Doubles from €70.
The Vatican full-day tour runs every Saturday, €40pp (biglietteriamusei.vatican.va).
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