Interior elevations of the church

The church has a chevet with three apses, the central one larger than the lateral ones. The main chapel, with a cylindrical interior enclosure, is organized in three levels, separated by imposts. The lower one, a smooth facing; above it, the three semicircular molded lighting openings, framed by a blind arcade; and the upper level pierced by five open oculi interspersed between blind semicircular arches. The hemicycle is closed with an oven vault, preceded by a pointed barrel vault and a double pointed arch, a space that is embellished with sculptural decoration carved in the capitals. On the other hand, the lateral apses present simpler solutions, perforated by a single central semicircular opening, traversed at the top and bottom by imposts, and covered by an oven vault, preceded by a double embouchure arch. 

The changes from the first to the second construction phase of the church, corresponding to the last third of the 12th century, can be seen mainly in the Wayside Cross, which in the arms adopts square cross arches, on which are supported the four independent plements that close it, a vaulted solution that is also used in the three sections of the naves, reinforced by rectangular section pointed sash arches, as opposed to the barrel vaults initially planned. The crossed arches or ribs rest on the columns of the pillars, while the wider sashes rest on the double columns of the pillar fronts. 

The incorporation of the formeros arches for the lateral shoring of the plements and unloading of the perimeter walls made it possible to lighten the wall, opening internal perimeter galleries, both in the main nave and in the side ones, which are accessed by the spiral staircases built in the tower of the western façade, linking the upper corridor with the choir, galleries that in the upper parts of the westernmost sections of the main nave and in the upper walls of the dome are illuminated with pairs of oculi. The elevation of the central nave is composed of slightly pointed arcades and a clerestory for illumination. The entrance of light through the foot of the church also comes from five large pointed, symmetrical and decreasing windows that pierce the upper closing of the western gable.

The church is embellished with an interesting collection of capitals, made by at least two workshops, the one that sculpted figures of short and limited artistic range, and the one that carved more stylized, detailed and meticulous figures. In the case of the four capitals of the pillars, plant motifs, scenes of fights between horsemen or religious themes were carved. The keystones of the vaults of the nave and transept arms are also noteworthy, as they are the first ones in Navarre, with themes such as the Pantocrator, trumpeter angels, the martyrdom of St. Stephen and the Right Hand of the Lord, among others, and the life-size tetramorph sculptures, with the human body of the evangelists and the head of their respective animal-symbol, arranged under the trumpets of the dome of the dome of the dome that closes the Wayside Cross This dome, of square plan and octagonal body, lost its original vaulting of crossed arches at the end of the 16th century, when it was replaced by a dome of average orange on avenerate trumpets, arranged in 1600 with the Riojan Domingo de Sarasola.

In the last third of the 16th century the church was intervened in the westernmost space, building a choir loft that occupies the last section of the central nave, in which the brothers Juan and Pedro de Gabiria worked in 1580. It rises on a lowered arch that rests on columns, with the front and capitals sculpted with Renaissance decoration, closing the choir loft a complex ribbed vault.