The church of San Pietro stands in its essentiality on one of the hills that precede the foothills and which dominate the Serenissima motorway and the state road, whose route follows the path of the ancient Postumia, a fundamental road axis that connected Genoa to Trieste. Guardian of the events that for centuries have characterized Caldiero and the life of the plain below, despite its historical value, the building has been affected by phases of neglect and abandonment alternating with moments of rediscovery and valorization that have reiterated the indisputable link with the territory and its community.

Although the historical sources do not allow us to assert it with certainty, some scholars hypothesize that the church of S. Pietro in Colle may correspond to the parish church of Caldiero, mentioned in the sources since 1145 in a bull of Pope Eugene III.

At present, based on concrete data such as morphology, construction technique and interior pictorial decoration, it can be stated that the building belongs to the first half of the 12th century. Following the construction of the new parish church dedicated to San Giovanni in the 16th century, the church of San Pietro, now unable to satisfy the needs of the community, became its chapel. The restoration of the interior pictorial decorations of the 12th century dates back to 2002.

The architectural structure, whose dating varies between the 11th and 12th centuries, is characterized by extreme simplicity. The building has a gabled facade facing west, with no decorative solutions and openings that probably date back to the 18th century. On the south side of the presbytery there is the quadrangular bell tower. The church has a single rectangular hall plan, with a presbytery raised by a step which ends with a semicircular apse.

However, the true richness of the church of San Pietro is preserved by its pictorial apparatus. Once the interior was entirely decorated but the instability of the hill and centuries of neglect caused the loss of a large part of the frescoes; those that remained were saved thanks to the restorations of 2002. The paintings, which belong to a time span between the 12th and 15th centuries, favor Marian subjects, paratactically inserted in frames, or depictions of saints such as Saint Bartholomew, Saint James and of course Saint Peter, the apostle to whom the Church is dedicated. Overlapping layers of plaster reveal decorative phases of different eras, which may reproduce the same subject or introduce new ones.

The apse depicts in the basin the Majesty with the Christ “in mandorla”, whose few fragments make it possible to hypothesize a thirteenth-century decoration in agreement with the second layer of the hemicycle, where the representation of the Twelve Apostles remains barely recognizable and overlaps with the original representation, also of the Twelve, dated back to the 12th century. Not much earlier are the frescoes of the triumphal arch and the northern apse, which constitute the largest and most uniform decorative system of the church.

Thanks to the restoration, the enamelled colours of the frame with perspective meanders have been recovered. In the triumphal arch, dominates a scene that is difficult to interpret due to the few remaining fragments. In a rectangular folder dominates the face of Saint Elias whose face, frontal and hieratic, is composed of a consistent line that traces long eyebrows and then becomes thinner to outline the sharp nose. His large eyes stare serenely but decisively at a distant point; his face is framed by a white beard and bipartite hair in the middle that falls symmetrically along his shoulders. Under the frieze, on a blue background, there are fragments of a scene that is difficult to read, in which a blessing hand, a reclining face and part of a robe can be distinguished, referable to two different figures. It could be an Annunciation or the archangel Michael who introduces the souls of saints in an offering attitude to God, symbolized by the manus Dei.

Nothing certain can be expressed about the interpretation of the scene but it is clear that the triumphal arch belongs to a single decorative campaign, which proposes the same stylistic features of a “Westernized Byzantinism”, based on the solid power of the dark line flanked by the green and the highlights that create volumes. The decoration of the left apse, in continuity with that of the triumphal arch, presents the triadic depiction of two saints, San Pantaleone and a holy monk, and of the Clipeated Christ. The good conservation of the frescoes allows us to define more clearly the language of Romanesque art, which cannot ignore the Byzantine experience.