This huge building, built of red sandstone, partly rebuilt in the 14 and 15C, and restored in the 19C, is topped with two Gothic towers from which there is a lovely view over the city. The main door is decorated with delicate sculptures of angels and prophets; on the left of the building is that of St-Gall, in Romanesque style. The interior has five naves and houses several 11C decorative elements.