According to tradition, the church choir covers the remains of an older building, possibly dating back to the 6th century, which was built to house the saint's body. According to current knowledge, the commune of Saint-Piat (Sanctus Piatus in Latin) officially appeared in 1087, mentioned in a charter of the Nottonville Priory (Eure-et-Loir), on which it depended.
The current building was rebuilt during the time of Francis I, as suggested by the date 1535 engraved on two buttresses of the apse and the date 1542 engraved on a piece of wood from the vault. This is according to a study by the SAEL (Eure-et-Loir Archaeological Society).
The three-sided apses, the dripstone towers (horizontal members projecting from a wall), and the sculpted roof structures are a testament to the importance of the reconstructions carried out in the department during the 16th century. The church of Saint-Piat is one of them.
While the church has not been officially recognized, it nevertheless contains objects that have attracted attention both for their antiquity and quality, but not always for good reason. Their artistic value, far from attracting only religious or aesthetic interest, has also aroused a covetousness that, unfortunately, remains for some of them. Fortunately, those still in place are carefully cared for and offer the curious a story to discover, a beauty to slowly ponder as they progress toward the choir.