San Pietro in Ciel d'Oro (Italian for 'Saint Peter in Golden Sky') name refers to the mosaics of gold leaf behind glass tesserae that decorates the ceiling of the apse.
A church of Saint Peter is recorded in Pavia in 604; it was renovated by Liutprand, King of the Lombards (who is buried here) between 720 and 725. The present Romanesque church was consecrated by Pope Innocent II in 1132.
The church is the resting place for the remains of Augustine of Hippo, who died in 430 in his home diocese of Hippo Regius, and was buried in the cathedral there, during the time of the Vandals. According to Bede's True Martyrology, the body was removed to Cagliari, Sardinia by the Catholic bishops whom the Arian Vandal Huneric had expelled from north Africa. Bede tells that the remains were subsequently redeemed out of the hands of the Saracens there—by Peter, bishop of Pavia and uncle of the Lombard king Liutprand—and deposited in the church of Saint Peter about the year 720.
In January 1327 Pope John XXII issued the papal bull Veneranda Santorum Patrum, in which he appointed the Augustinians guardians of the tomb of Augustine (the Arca di Sant'Agostino), which was remade in 1362 and elaborately carved with bas-reliefs of scenes from Augustine's life. The actual remains of Augustine, however, were no longer identified. Then, on October 1, 1695, illiterate stonemasons working in the crypt altar removed paving blocks and discovered a marble box. Within it were other boxes; in the third box were fragments of wood, numerous bones and bone fragments, and glass vials. Some of the workers later claimed to have seen the name 'Augustine' written in charcoal on the top of the box. A factor complicating the authentication of the remains was that San Pietro in Ciel d'Oro was shared by the two Augustinian religious orders in bitter rivalry. The controversy on the authenticity of the bones resulted in broadsides, pamphlets and books. In 1728, Pope Benedict XIII's intervention in Pavia resulted in his approval of the authenticity of Augustine's bones discovered in the church of San Pietro in Ciel d'Oro.
The Augustinians were expelled in 1700, taking refuge in Milan with the relics of Augustine, and the disassembled Arca, which were removed to the cathedral there. The erstwhile cathedral in Pavia fell into disrepair; it was a military magazine under the Napoleonic occupation. It was not reconstructed until the 1870s, under the urging of Agostino Gaetano Riboldi, later Cardinal Riboldi, and reconsecrated in 1896 when the relics of Augustine and the shrine were once again reinstalled.
References:The first written record of church in Danmark locality date back to the year 1291. Close to the church are several stones with a Christian text and cross inscribed. The oldest parts of the present red-brick church are from the 1300s. In the late 1400s the church was enlarged to the appearance it has today. The church has been modified both internally and externally several times, among other things after the fires in 1699 and 1889. There are lot of well-preserved mural paintings in the walls.