It was Bishop Ermengol who began the work on the Romanesque cathedral in the 11th century, however, the church was knocked down half a century later and the one that remains today was erected. Construction was completed in 1183. It possesses an exemplary Romanesque style with Lombardic influences on the exterior. It has a basilica ground plan with three naves and a transept with five apses.
The façade has three entrances. The cloister has decorations with plant and human figure motifs in the capitals. The choir, the railings, the stained glass windows and the reredos are from the 15th century and there are also some 18th century Baroque elements. The Diocesan Museum contains the Commentary of the Apocalypse, a Mozarab miniature from the beginning of the 10th century.