The church-oratory of S. Maria delle Grazie del Furlo and the Roman Tunnels

The church-oratory of S. Maria delle Grazie is known by several different names, beginning with its “official” title «Maria Mater Gratiae», written on the altar; it is also known, in fact, in documents as well as in popular tradition, as Madonna delle Grazie, chapel of S. Maria, Beata Vergine del Furlo, Madonna del Furlo or della Botte. These last names derive from the particular site where it stands, at the Furlo gorge, “a wonderful work of nature”.

The little church and the gorge that welcomes it are inseparable and their boundaries are lost. The small building which seems so naturally to emerge from its surrounding environment, was erected on the ancient road of the Via Flaminia, near ​​the Roman tunnels, adapted from a previous construction.
Human intervention was particularly significant where the road had to overcome numerous natural obstacles; this resulted in the construction over centuries of massive artificial works to make the road passable, or rather, the route passable: from prehistoric tracks, also due to the seasonal transferral of livestock towards Apennine pastures, to the routes of the pre-Roman era when the Furlo represented the shortest passage from Rome through the Apennines towards the north-eastern territories; finally, the Romanisation after the battle of Sentino (295 BC) and the foundation (268 BC) of Ariminum (Rimini) when in around 220 BC an organic structure was given to the consular Via Flaminia, which also came to fulfil the important role of “military road” during the Hannibalic War, especially with the battle of the Metauro (207 BC).

Along this stretch, the successive interventions are still recognizable in the wavy and winding path, raised by about thirty meters from the riverbed, a safety level obtained sometimes by powerful cuts in the rock face, in other cases by building long terrace walls and finally by the demanding excavation of two tunnels: the most significant construction phases were the first opening of the Via di Gaio Flaminio, its general restructuring wanted by Augustus and the decisive intervention carried out under Vespasian.

The Flaminia road, along the approximately three kilometer narrow stretch, was cut from the bare rock face on the side of the hill above the gorge and needed reinforcing by retaining walls. Towards the north-eastern end, the gorge narrows further and presents a spur of Mount Pietralata that drops steeply to the riverbed. It is therefore possible to recognize in a stretch of about three hundred meters a series of man-made interventions from different periods, which can be arranged in chronological order also thanks to a scale plan of 1720 in which the original phase of the Flaminia and the church of S. Maria delle Grazie can be identified.

The ruts of the roadway, caused by the wheels of the carts that for about two centuries traveled in both directions along this part of the road, are still clearly legible on the rock surface. Various similar substructures preserved along the gorge belong to the redevelopment program of the Augustan age: at the end of the nineteenth century the surviving ancient walls, 8-10 meters high, were lengthened by 506 and subsequently by a further 424 metres. Like the adjacent terrace wall, which reinforces its structure, probably at risk, located on the edge of the cliff, it is believed that the small Gallery is also due to an emergency intervention, judging by its appearance, it being of such an irregular shape and considering its dimensions, barely suitable to allow the passage of one cart at a time. The length of the passage is about eight meters, the width on average is 3.30m and its maximum height is 4.45m; the same irregularity found in the measurements can also be noted in the sixth of the vault.

This small and perhaps precarious tunnel was a sort of shortcut, which allowed a narrow emergency passage to the Via Flaminia, avoiding having to go all the way round the steep mountain, even if local tradition believes it to be the work of the Umbrians or other primitive people (LUNI 1993) or of the Etruscans. It is difficult to date the structure accurately, but the massive substructure may have been from the Augustan age and the large gallery opened in the Vespasian era, also due to subsidence of the road surface.

Looking east, beyond the end of the “chapel of S. Maria”, there is a significant gap in the side of the cliff due to an ancient landslide; the original road surface had been reduced to a narrow path, which made it difficult to cross the gorge. It was reported that in 69 AD the troops of Emperor Vespasian fighting against Vitellius remained blocked at Fanum Fortunae for a certain time because the Flaminia in the nearby impervious gorges was not safe, so much so that Vespasian a few years later solved the problem by opening the Great Gallery as part of the larger restructuring intervention of the important road.

With the new tunnel, the original road, which went all the way round the mountain, was definitively abandoned; the commonly proposed date is 76 AD, referring to the completion of the tunnel, certainly begun before that year; its length is approximately 38 meters, the width varies from 5.47 in the center to 5.35 on the side towards Cagli, to 5.23 at the entrance towards Fossombrone.