Known locally as the "Glass House," the towering 26-meter-tall (85 feet) stained-glass windows floor the sanctuary with an ethereal, shifting glow. Hanging in the center is the golden Strahlenkranzmadonna ((Radiant Madonna) from 1524, hovering directly between two of Western Europe's most significant medieval artifacts: the golden shrines housing the relics of the Virgin Mary and the bones of Emperor Charlemagne.