Sion Cathedral, Catholic cathedral in Sion, Switzerland.

Sion Cathedral is a three-aisled basilica with a transept and a long choir, built in Gothic style from 1450 to 1500 on Romanesque foundations. Its massive Romanesque tower with a conical spire dominates the cityscape. The portal tympanum holds a fresco in the style of the northern Italian Trecento, showing the Mother of God flanked by two holy bishops and donor figures.

A Carolingian church stood on this site around 800 and burned in 1010; the Romanesque cathedral that followed was sacked by Amadeus VI of Savoy's troops in 1352. Between 1450 and 1500 the nave was rebuilt in Gothic style under bishops Walter Supersaxo, Jost von Silenen, Nikolaus and Matthäus Schiner, keeping the 12th-century tower. The roof burned in the town fire of 1788, and the choir was lengthened by two bays in 1947/48.

The name Glarier refers to the gravel bank of the Rhône where the cathedral stands. Its patronal feast is the Assumption on 15 August. In the Chapel of Saint Barbara, founded in 1474 by Bishop Walter Supersaxo, frescoes uncovered in 1948 show the wise and foolish virgins, Saint George and the princess, and the martyrdom of Saint Sebastian, painted by the Bavarian master Thomas von Landsberg in 1475.

The cathedral is oriented east, with the Romanesque tower and portal on the west front and the choir extended two bays eastward in 1947/48. The Chapelle Sainte-Barbe opens off the right of the transept, and the Chapelle Saint-Antoine holds the 1683 baroque altar. The organ loft carries the arms of prince-bishop Frédéric Ambuel and the cathedral chapter, dated 1780.

The cathedral's seven bells hang in the Romanesque tower: two date from the 15th century, the other five from the 16th to the 19th century. The tower itself, with its conical spire, survived the fires and wars that destroyed the earlier naves.