SAGRA DI SAN MICHELE. – Popular designation of an ancient Benedictine abbey, in the diocese of Susa, built on a spur (Monte Pirchiriano, 916 m.) at the entrance to the Valle Segusina, near the place where Desiderius barred Charlemagne’s passage (its true name is S. Michele delle Chiuse; in the Middle Ages it was called coenobium Clusinum).
Its origin dates to the end of the 10th century, when Hugues le Décousu de Montboissier, a nobleman of Auvergne, having to erect a monastery as a penitential injunction from the Pope (Giovanni XIV or XV, according to some; but more probably Silvester II), founded it near a small church dedicated to the archangel Michael, built—or rather restored—a few years earlier by s. Giovanni Vincenzo, formerly bishop of a city in the Ravenna region, who had withdrawn as a hermit on Monte Caprasio, opposite Pirchiriano.
Already under the first abbot (Avverto), the abbey attained considerable importance, which increased especially under the rule of Benedetto I (early 11th century), Benedetto II (d. 1091, founder of the abbey school and teacher of the monk Guglielmo, the Clusine chronicler), Guglielmo I (early 12th century), Stefano (mid-12th century), and Elia (first half of the 13th century), and reached its greatest splendor (approximately 300 monks, 140 churches and abbeys under its jurisdiction) with Rodolfo di Mombello (d. 1359). In the second half of the 14th century, a rapid decline set in, beginning with the simoniacal election of Pietro III to the abbatial seat (1362) and culminating in 1381 with the transition to the commendatory system, promoted by Amedeo VI of Savoy in order to curb the monks’ corruption. For several years during the 16th century, the commendam was held by the Ferrero, a noble family from Biella; it also went several times to the House of Savoy, and at the request of Emanuele Filiberto, Pope Gregorio XV suppressed the monastic community, assigning the abbey’s revenues to the establishment of the collegiate church of Giaveno, to whose care the monastery remained entrusted. Carlo Felice chose the temple’s crypt as the burial place of the members of a collateral branch of the House of Savoy. In 1803, Pio VII placed the territory under the jurisdiction of the archbishop of Turin, and finally, in 1836, Gregorio XVI established the Rosminians there.
Of the building complex, irregular because of the nature of the site itself and the superimposition of successive architectural developments, the church and the so-called «tomb of the monks», a circular-plan building of the Romanesque period now in ruins, are noteworthy. The church consists of three distinct phases: the crypt, perhaps identifiable with the little church of s. Giovanni Vincenzo; the three Romanesque apses (of which the central one is the largest), resting on enormous substructures 23 m. high and dating to the 12th century; and the body of the church, from the 14th century, in the Gothic style. The access, through a staircase cut into the rock («stairway of the dead»), is noteworthy for the «zodiac door», which bears the signature of a Nicolaus, identified by some, on account of certain affinities in the sculptural motifs, with the author of the right portal of Piacenza Cathedral.