The Church of Saint Peter of Montmartre (French: église Saint-Pierre de Montmartre) is the lesser known of the two main churches in Montmartre in Paris, the other being the 19th-century Sacré-Cœur Basilica. Historically, however, it has the greater claim to fame, since, according to the earliest biography of Saint Ignatius Loyola, the church is the location at which the vows were taken that led to the founding of the Society of Jesus.
Though according to its traditional history, it was founded by Saint Denis in the third century, only scattered signs of Gallo-Roman occupation have been detected at the much-disturbed site, where Théodore Vacquier, the first municipal archaeologist of Paris, identified remains of walling as belonging to the Temple of Mars, from which Montmartre took its name. In 1657, the antiquary and local historian Henri Sauval was shown remains in the priory garden that he associated with the templum Martis. The early church that was a stop in the ninth century for pilgrims en route for the Saint Denis Basilica, belonged in 1096 to the comte de Melun. Louis VI purchased it in 1133, in order to establish in it a Benedictine Abbey, and the Merovingian church was rebuilt; it was reconsecrated by Pope Eugenius III in 1147, in a splendid royal ceremony where Bernard of Clairvaux and Peter, Abbot of Cluny acted as acolytes.