When Hadrian dreamt of getting away from it all, he dreamt of Sabina. Fed up with the noise, the traffic and the parking restrictions of Rome, he wanted somewhere green, somewhere rustic, somewhere not too far from the Via Tiburtina. He might even work from home for a few days a week. With carrier pigeons, you didn’t need to be in the Senate every day.

He was not alone. Sabina was the Gloucestershire of ancient Rome. On Friday afternoons, the Via Tiburtina was choked with chariots. Strabo waxed lyrical, and Pausanias bored his friends with how marvellous it was. Horace had a farm here that he endlessly eulogised. “Never would I exchange my Sabine farm for riches,” he wrote, presumably referring to rising property values.

Which makes it surprising that Sabina has fallen into obscurity. If you mention the region to a modern Roman, it might produce a shrug. They are unlikely to have been there. For foreigners, it is almost unknown. Guidebooks pass over Sabina with a line or two, and tourist itineraries leave it almost untouched.

Yet this is one of the loveliest areas of Italy. Back roads wind through olive groves and pastures of sheep, beneath medieval hilltop towns and old abbeys and vine-draped farmhouses. Famous for the quality of its oil, Sabina is famous, too, for the greenness of its hills in months when the rest of Italy is often dry and brown. Sabina is as beautiful as Umbria, which it borders, without the drone of tour buses or the shrill ring of English voices.

But most remarkable of all is its location, the location that recommended it to Hadrian. We expect our hidden gems to be remote, difficult of access, off the beaten track. Sabina is just over half an hour from Rome, just off the autostrada. On a clear day, from some of its hill towns, you can see the dome of St Peter’s.

Among those who know and love Sabina, there is considerable debate about why it has been so overlooked. Some claim it is due to the character of the locals, who are modest, unassuming types, unlike their more vociferous neighbours just to the north in Umbria and Tuscany. But the real reason probably lies in what it lacks.

For foreigners, it lacks famous sights. Sabina has no cities, and thus no great museums, no cathedrals. This is a region of villages and secondary roads. This is slumbering rural Italy. There is nothing to see in Sabina, in the way that there is nothing to see in the Cotswolds.

Yet even this explanation is too simple, for people are waking up to the fact that Sabina is the ideal base from which to see Rome and its surroundings. Sabina offers Rome as Hadrian liked to see it: with the benefit of a little distance. From Poggio Mirteto, you can catch a train into the city in the morning, spend the day exploring the sights, have dinner in Trastevere and be back in the hills in time to watch the moonlight sidle through the olive groves while sipping a digestivo on the terrace.

It is also an ideal base for touring much of central Italy. It is less than an hour to Viterbo and Orvieto. The Umbrian towns of Todi and Spoleto are a similar distance, while Perugia and Assisi are only 90 minutes away. The only problem with Sabina is that, once there, you don’t want to leave.

I stayed at Borgo Paraelios, a beautiful retreat with an old-fashioned country-house feel. Breakfast was on a trellised terrace surrounded by bird song and climbing greenery. I knew I should be out exploring, but actually

I just wanted to curl up in a hammock with Hadrian’s memoirs and the drone of cicadas. It had a spa with pampering treatments, a sauna and Turkish bath, and one of the most beautiful indoor pools in Italy.

When I finally did tear myself away, I drove over to Villa Adriana, Hadrian’s retreat at Tivoli, which was 45 minutes away. In classical times, Tivoli was very much part of Sabina. But the boundaries of the region have shrunk since Hadrian’s day, as if, in trying to keep the secret of itself, Sabina has lopped off any bits that became famous, anywhere that might attract tourists.

Being emperor, the big man needed to create a country retreat that would pack a little punch. The buildings alone cover 100 acres; the gardens extend to another 200. At the time, it was said to be the grandest villa in the Roman empire, presumably in the known world, though the term villa hardly does it justice. It would make Versailles look cramped.

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