This huge red sandstone building, partially rebuilt in the 14C and 15C, and restored in the 19C, is topped with two Gothic towers. The main door sports delicate sculptures of angels and prophets; on the left of the building is that of St-Gall, in Romanesque style. The apse, partly Romanesque, overlooks the "Pfalz" terrace (name of the former bishop's "palace"), which commands a fine view. The interior has five naves and houses several 11C decorative elements.