Exterior of the church

The exterior of the church is a harmonious play of volumes, with the triple apse, the arms of the Wayside Cross and the Romanesque octagonal dome with four cylindrical bodies arranged on the equines, topped by a conical stone roof, followed by the three naves of the church, the central one being taller, and the bell tower at the foot on the northwest flank. 

The central polygonal and larger apse stands out in the chevet, reinforced by four straight prismatic abutments. The three apses share a smooth lower impost, the articulation of the openings and an arcade of blind trilobules on which the tile roof is mounted. In the second construction phase of the temple, begun in the last third of the 12th century, the exterior corbels of the central apse were made, outstanding from the artistic point of view for their great quality and beauty. On them were sculpted human figures, real and fantastic animals, as well as human heads or torsos carrying stonecutting tools, which has led to speculation as to whether the artists themselves were self-portraits.

The exterior of the naves is dominated by the ashlar wall, which gives a sense of horizontality and heaviness, in the absence of buttresses that divide the sections. The north arm of the Wayside Cross, illuminated by a large oculus, is Closed by a modern wall built in 1982, when the 17th century Baroque chapel dedicated to St. Veremundo was inexplicably removed. 

In the intermediate section of the northern wall is the old cemetery door or door of San Pedro, from the end of the 12th century, slightly pointed and flared, with five archivolts of elaborate molding that rest on columns. The sculpted decoration on the capitals, very deteriorated, sample fight scenes, with humans or fantastic animals, and monsters or paired animals, as well as two scenes from the life of St. Martin. 

On the western façade, the tower of the north side conserves a good part of the primitive medieval factory in the three descending bodies of unequal heights, topped with a square bell tower, of clear Escorial influence executed agreement the design presented by Diego de Sisniega, stonemason neighbor of San Mamés de Trasmiera, conserved in the General file of Navarra, work that he contracted together with his nephew Juan González de Sisniega in 1601 and that was concluded in 1609. The bell tower of Herrerian language is articulated by four pilasters on each of its fronts, between which are interspersed semicircular openings that house the bells and side blind niches on which are arranged placados, culminating in a balustrade with balls on the pilasters and the dome with lantern.

Attached to the tower is a narthex covered with three sections of pointed barrel vaulting, reinforced with three transverse arches that rest on corbels with figured capitals. In its front is located the main door of access to the temple, of the XIII century, formed by five smooth and pointed archivolts that rest on columns and capitals with stylized vegetal motives. The core topic of the entrance arch sample a chrism supported by the hand of Christ. Above it are five small staggered semicircular openings with a continuous balustrade, which facilitate the illumination of the church in this space at the base. The upper part of the façade was redecorated following the baroque taste, with a body articulated with cut pilasters, with motifs of foliage that frames a niche with the sculpture of the Immaculate Conception, outline that is referred to in the auction with the image of San Veremundo.