and the rest of the nave. The alternating courses of brick and stone give way to a predominantly brick technique with stone quoins and stone window frames. This third campaign includes the wall enclosing the entire nave, including the western entrance and ends just below the gallery windows. During the fourth phase, the remainder of the nave was completed in brick with almost no stone. The plan of the abbey church here was also used in the construction of the cathedral of Santiago de Compostela, "begun in 1082, too direct a copy to have been done by any but Saint-Sernin's own architect or his favored pupil", but finished much earlier. In 1860, Eugène Viollet-le-Duc restored the church, but his changes are currently being removed to restore the original appearance. Features Despite being called a basilica, Saint-Sernin's deviates from the basilica plan of early Christian architecture in a few ways. It is much larger compared to earlier churches, measuring 104m in length. It is also constructed mostly of brick. The building is in the form of a crucifix. The ceilings are vaulted, unlike many of the earlier churches. Saint-Sernin's contains radiating chapels which were used to display important relics. Another deviation from the earlier Christian churches is the addition of an ambulatory, a walkway that goes around the nave and side aisles to allow for viewing of the radiating chapels (which could be done while mass was being held without interrupting the ceremony). For these and other reasons, Saint-Sernin's is often said to follow the "pilgrimage plan" instead of the traditional basilica plan. Exterior On the exterior, the bell tower, standing directly over the transept crossing, is the most visible feature. It is divided into five tiers, of which the lower three, with Romanesque arches, date from the 12th century and the upper two from the 13th century (circa 1270). The spire was added in the 15th century. The bell tower is slightly inclined towards the west direction, which is why from certain standpoints the bell tower roof, whose axis is perpendicular to the ground, appears to be inclined to the tower itself. The chevet is the oldest part of the building, constructed in the 11th century, and consists of nine chapels, five opening from the apse and four in the transepts. The exterior is additionally known for two doorways, the Porte des Comtes and the Porte Miègeville. Above the Porte