The abbey of San Pietro al Monte, above Civate in the province of Lecco, is one of the few great monuments of Lake Como that cannot be reached by car. There is no road, no car park in front of the churchyard, no shuttle.

There is a cobbled mule track that starts from the last houses of the hamlet of Pozzo, enters the woods on the slopes of Monte Cornizzolo and climbs for two and a half kilometres with four hundred metres of elevation gain. An hour's walk, the last part on steps.

At the top opens a grassy plateau with three things on it: a Romanesque basilica left as it was in the 11th century, an oratory dedicated to Saint Benedict, and the ruins of the monastery. Below lie Lake Annone, Monte Barro and the silhouette of the Resegone.

The sources disagree on the altitude, with a range from the 630 metres of some listings to the 662 declared by the association that manages the site. What does not change is that the climb has to be done on foot: the paths are not suitable for bicycles.

The tale of the origins comes from the Dominican friar Galvano Fiamma, who wrote in Milan in the fourteenth century, probably copying from an older document. Desiderius, the last king of the Lombards, stops at Civate.

His son Adelchi goes hunting on the Cornizzolo and chases a boar to a clearing, where a hermit named Duro is building with his own hands a small oratory dedicated to Peter. The beast enters through the open door and lies down at the foot of the altar. The prince follows it with his spear, ignores the hermit's pleas, and at the moment he violates the sacred place he loses his sight.

He recovers when the hermit washes his eyes with water from a spring that still flows beside the church, and his father, in gratitude, has the sanctuary built at his own expense.

It is worth bearing in mind the date of the teller: Fiamma writes more than five hundred years after the events, and his story has the classic structure of foundation legends, with the animal that asks for asylum, the powerful man who breaks down the door, the punishment, and the penance that turns into stone.

The white boar, protagonist of the later versions, is a sacred animal in the Celtic world, and it hints at a pre-Christian substratum absorbed into the tale.

That something stood up here before the Lombards is probable: traces remain of a tower, chapels, columns and masonry datable between the 5th and the 8th century. The first written document dates to the 9th century and mentions Abbot Leutgar with thirty-five Benedictine monks, linked to the Swiss monastery of Pfäfers.

The decisive moment is the 11th century. In 1097 Arnolf, Bishop of Milan, had himself buried at San Pietro after spending his last years there, and his presence is almost certainly what set in motion the construction of the present church.

Then the story took a very bad turn. The monks sided with Frederick Barbarossa, the free commune of Milan destroyed the monastery in retaliation, the community moved down to the valley and only a few hermits remained up there. With the construction of the church of San Calocero in the village, San Pietro progressively fell into ruin.

In the mid-sixteenth century the Olivetans arrived, and they held out until 1798, when the Cisalpine Republic brutally expelled them. In the nineteenth century the bell tower that stood outside the church was also demolished.

The decorative cycle has come down to us intact precisely thanks to the abandonment: nobody had the money or even the interest to redo San Pietro in the Baroque style, as happened almost everywhere else in the diocese.

The 11th-century enlargement flipped the axis of the building: the old apse, to the east, became the entrance, and to the west a new one was built with the altar. The result was a single nave with two opposing apses.

Not all scholars accept this reconstruction: some argue that the church was born like this from the start, with two facing apses, following a model widespread north of the Alps.

You enter by climbing a staircase in green serpentine and granite, which leads to a semicircular atrium lit by mullioned windows and built on two levels: the upper one at the level of the church, the lower one at the level of the crypt, where pilgrims found shelter. Two stone portals bear the inscription Ora et labora.

Above the door, on the outside, is the fresco of the Traditio Legis et Clavis: Christ standing, arms open, hands the keys to Peter and the law to Paul.

The decorative programme is the reason the climb is worth it, and it is built almost entirely on the Book of Revelation. The main scene is on the inner façade, above the door through which you have just entered.

The woman clothed with the sun, with the moon under her feet, has just given birth to a child who is being carried to God's throne so that the dragon cannot devour him. The dragon has seven heads and stretches across the whole wall with its body and tail, while the archangel Michael and his angels pierce it with their lances.

In the vault of the entrance corridor is the heavenly Jerusalem: Christ enthroned on the globe, the Lamb at his feet and a river that immediately divides into four branches, and all around the walls of the city with twelve gates from which angels' heads look out.

In the next vault the four rivers of the earthly Paradise become veritable figures. Below, two stucco panels show a griffin and a chimera, symbols of evil, caught fleeing from the church.

Scholars date the whole between the end of the 11th century and the early years of the 12th, with no agreement on either the number of artists or their provenance: in the heavenly Jerusalem one recognises northern Ottonian models, while whoever painted the apocalyptic vision knew the Byzantine idiom of the second half of the 11th century.

At the western end, above the altar, stands the stucco ciborium, which in its structure closely resembles the one in Sant'Ambrogio in Milan. Four columns, the symbols of the evangelists in high relief above the capitals, and on the gabled fronts the Crucifixion, the Marys at the tomb, the Ascension and once again the Traditio Legis.

Inside the little dome a fresco shows the Lamb surrounded by eighteen figures with haloes, ten men and eight women, whose identity has been debated for decades.

From the nave you descend into the crypt by a staircase whose parapet is decorated with griffins, lions and lions turning into fish. Below, three small aisles on two rows of three columns and stuccoes dedicated to the Virgin: the presentation of Jesus at the temple, a crucifixion now very damaged, and a Dormitio Virginis of rare intensity.

Among the few frescoes that survive down here, a Saint Agnes holds a torch with a container of oil hanging from it.

On the walls of the nave the medieval scheme is almost entirely lost: what remains is a fifteenth-century Madonna enthroned and, opposite, a Madonna with saints signed in 1565 by Lazzaro Gerosa.

At the foot of the staircase, detached from the basilica, stands a small building with a square forepart and three semicircular apses, datable to the late 11th century. It never had baptismal functions: it served for prayer or for burials. Above the medieval masonry altar, still in place, are three 12th-century frescoes: Saint Benedict holding a book inscribed ego sum benedictus abas, Saint Andrew and a blessing Christ with the inscription ego sum lux mundi.

Around it the meadow is well kept, with benches and a few olive trees, and the ruins of the monastery close off the space towards the mountain.

This is the spot where almost everyone sits down to eat, and it is worth knowing beforehand: up there no food or drink is sold and there are no bins, so you climb with your lunch in your backpack and carry back down whatever is left over. There are, however, toilets.

You start from the hamlet of Pozzo, at about 380 metres above sea level. By car, leave the expressway at Civate and follow the brown signs for the basilica: the car parks are along via del Pozzo and via del Rii and on weekends and holidays they are paid.

By train, get off at Civate station on the S7 line from Milano Porta Garibaldi, and it takes about twenty minutes on foot to cross the village and reach the start of the trail. It is one of the few hikes in the Lecco area that can be done in a day without a car, like the Lecco branch described in Bellano.

Past the last houses, take trail 10, the one to the Cornizzolo. The first minutes are flat and lead to the locality of Oro, with a few houses, a chapel and a small fountain, the last water point before the basilica. From there the path steepens into the woods and in its last part becomes a long staircase of steps.

The association recommends hiking boots, and this is not excess caution: the cobbles, polished by centuries of passage, are very slippery, especially in the rain and in frost.

For the return you can go down the same way or close the loop with trail 11, which passes through the Dosso della Guardia and stays overlooking the lake almost the whole time, whereas the 10 stays inside the woods.

Those with legs and more time can continue upwards: in just under an hour from the basilica you reach the refuge below the summit and in another twenty minutes the cross of Monte Cornizzolo, at 1240 metres, from which you can see lakes Annone, Pusiano and Alserio and the tip of the Lecco branch of Lake Como. The full loop is about nine kilometres with nine hundred metres of elevation gain.

Spring and autumn are decidedly the best periods. In summer it is best to set off early, because the trail is shaded but the climb gives no respite.

From March to October the basilica is open on Saturday and Sunday from 10:00 to 12:30 and from 14:00 to 16:00.

From November to February the Sunday opening remains, from 10:00 to 12:30 and from 14:00 to 15:00, while for Saturday you must book by the preceding Wednesday.

From Tuesday to Friday entry is by reservation only and subject to the availability of the volunteers, by calling or writing by noon of the previous day. Monday it is closed.

It also opens on 25 April, Easter Monday, 1 May, 15 August and 26 December, and remains closed on Christmas, New Year's Day, Holy Saturday, Easter and All Saints' Day.

For the weekend the guided tour can also be booked online until midnight of the previous day, choosing among the time slots with free places. Groups of more than twenty people and school groups go through the telephone or email. If the weather is bad it is best to call before setting off, because the tour may be cancelled.

The visits are free and are led by the volunteers of the Associazione Amici di San Pietro, founded in 1975 around don Vincenzo Gatti, who coordinated its restorations for fifty years.

You may leave an offering, and the proceeds go to restoration and maintenance. There are also audio guides in Italian, English, German, French and Spanish. The 10:30 mass is guaranteed only on the first Sunday of the month: for the other Sundays the association gives notice midweek on its channels.

The internal rules are few. Photography is allowed without flash and only for personal use: for photos or footage intended for a publication, or made with professional equipment, the authorisation of the parish priest of Civate is required, and drones are not allowed.

Walking poles must be left outside or put in your backpack, because inside you pass a few centimetres from frescoes and stuccoes. Dogs may stay on the meadow but do not enter the church. Camping and lighting fires on the meadow are not allowed.

Since 2016 San Pietro al Monte has been on the Italian tentative list for UNESCO World Heritage, within the serial nomination on the cultural landscape of the Benedictine settlements of medieval Italy.

Unfortunately (one must be honest) it happens, especially on Mondays or to those who climb on a winter weekday afternoon.

The plateau, however, remains accessible: the staircase, the flank of the basilica with its hanging arches and the pilaster strips of the Comacine masons, the exterior of the oratory, the ruins and the panorama can be seen all the same. What you miss is the interior, that is, almost everything: it is worth planning a second climb on an opening day.

In the village there remain the basilica of San Calocero with its cloister, which opens on request, and the churches of San Nazaro and San Vito, part of the same Benedictine complex. Civate is ten minutes from the Lecco junction, easy to fit into an itinerary of a couple of days on the lake.

The best moment, if you can choose, is early on an October Sunday morning, when the volunteers open at ten and the light coming in through the mullioned windows falls straight on the fresco of the dragon.