It originally had a longitudinal layout with a single hall. It was rebuilt in the 17th century, and the ashlars of the pre-existing Romanesque building were reused to build external buttresses: two side chapels were also added in the quadrangular chancel, and it was covered with a barrel vault traversed by sub-arches. The bell gable tower is also ascribed to this period. Only the facade is preserved of the Romanesque church, built with sharp-cut limestone blocks that make regular, sometimes non-uniform rows. It appears devoid of corner pilasters: in the corners it turns up a simple molded cornice on which rests the first of the thin double ferrule arches: there are nine of them and they make a horizontal arching that separates the smooth, unterminated part above. One of the small arches is decorated with engraved geometric motifs; human protomes, bucrania, water leaf, and ram protome are carved in the corbels, lower with spindle frieze. The portal is architraved with a semicircular lunette: trachyte ashlars alternating with limestone can be discerned in the arch, in two-tone. For the chronology of the Romanesque building, comparisons on a stylistic basis would lead to its being ascribed to the mid-12th century (particularly because of the facade lacking corner pilasters and the elongation of the pier in the side arches): moreover, it was noted that these stylistic features were typical of Romanesque architecture in Corsica, aspects for which it is assumed that the building was executed by Corsican-trained workers.
