The primitive abbey was founded in 1137 when Bernard of Clairvaux sent a colony of monks to Rieti headed by the holy abbot Balduino: they settled in Monticulo,[4] where a structure of the Benedictine order already existed.

This prompted the monks to seek a location farther from the valley floor, so on March 14, 1234, at the springs of Santa Susanna, Cardinal Goffredo Castiglione (future Pope Celestine IV) ratified a contract by which the abbey was moved to the area of San Pastore, in which a corte, a group of houses with a church, had already been known to exist since the 8th century.

[1] Subsequently, a period of decline began, due to the bad administration and poor morality of the monks:[1] traces of this situation can be found in the accounts of the apostolic visitors of the time, and 1373 Pope Gregory XI commissioned the abbot of San Lorenzo Outside the Walls to visit and reform the monastery.

[7] From that time on, the abbey was abandoned and fell into a deep state of decay, which persisted until the threshold of the third millennium: the roof collapsed, it was overrun by grass, and because of the broken fixtures, the most valuable artistic relics were stolen: frescoes, fireplaces, doorposts, doors, squared ashlars, and even a stone spiral staircase.

[2] In the early 20th century, the Ministry of Education, with the contribution of Prince Ludovico Potenziani, made partial repairs to the building[6] and Giuseppe Colarieti Tosti restored the church frescoes,[11] but the state of decay was not resolved and looting continued.

[8] Today the site is used for events such as workshops, corporate meetings, weddings, receptions, exhibitions, and concerts,[12] while four suites are being set up that will make the abbey capable of tourist accommodation.

According to Negri, the abbey of San Pastore is an example of “Cistercian achievement of a still archaic cut because of the continuous and consistent use of stylistic features ascribable to the Order's first construction phase, such as the pointed barrel vault on the apsidal part (and perhaps on the entire church), the round arches in the chapter house, and the ogives always in a straight section, which refer to other Italian churches of the period-Falleri, Tre Fontane, San Nicola di Agrigento.”[5] The current form of the cloister dates from 1638 when the Lateran Canons restored it.

[2] A valuable painting of the Crucifixion, dating back to the 16th century and depicting Christ crucified, Mary Magdalene weeping, the Virgin, St. Thomas, St. John the Evangelist, and St. Matthew, was also originally in the church.

[11] The canvas, which according to Sacchetti Sassetti is to be attributed to the Veronese brothers Lorenzo and Bartolomeo Torresani while according to Palmegiani it has the characteristics of the Umbro-Roman school, was moved by the Potenziani to the small church of an estate the owned.