The cathedral’s interior contains a rich collection of stained glass windows (more than 4,600 panels), most dating from the 12th, 13th and 14th centuries.In the north collateral, they represent different Emperors of the Holy Roman Empire (13th century).The triforium’s stained glass windows represent Christ’s ancestors following the genealogy of the Gospel of Luke. Those of the south lateral nave (to the right, coming from below) are in bad condition and illustrate episodes of the New Testament of the life of the Virgin Mary and Christ.The stained glass windows of the nave depict the life of the Saints.