The palace at Aix, like the church, has for its model a building at Ravenna, the so-called palace of Theodoric. As all of the dependents of the court had to be accommodated, the ground floor covered a considerable space. In the center were the apartments of the imperial family, the audience chamber, the baths. In a large wing of the building, connecting it with the chapel, there was room for the school, the library, the archives. In interior decoration stucco, mosaic work, and mural painting were used rather than sculpture, in which art Carolingian workers showed little skill. The Emperor, though he prohibited the worship of images, expressly directed the use in church of mural paintings, with subjects taken from the Scriptures. In the palaces the same art was used to illustrate the secular history of the Empire. The Emperor’s deeds were depicted on the walls and explained in poetical inscriptions. Mosaic was used for floors and wall spaces, and red and green porphyry were especially sought after for the decorative designs that often covered the interior of the cupola, as at Aix, where the Christ is represented on a gold background covered with red stars, blessing twelve aged men at his feet, and accompanied by two angels. Work in the precious metals and in ivory was frequent in the churches, since each had a treasury, and a third of the income, saved from tithes, was assigned for religious ornaments. In these collections gold reliquaries with chased work and precious stones were specially valued; also portable altars and ciboria. The “ivories,” of which interesting specimens are still preserved, are remarkable for the care displayed in continuing the traditions of this branch of Christian art, as practised both in the Eastern Empire and in Italy during earlier centuries. Books are recorded also in the inventories of the church treasuries, and the specimens that have survived attest the artistic value of Carolingian calligraphy. The style of writing, under the influence of English and Irish models, is clear and free from abbreviations. Besides the miniatures, these manuscripts exhibit artistically drawn letters, effectively combined, and characters done in gold and silver on a purple background. There were a number of schools where the art of copying was taught, the most celebrated being at Tours, under the supervision of Alcuin. The national library at Paris has a beautiful example of this work in a book of the Gospels prepared for Charles in 781, by the monk Godescalk. In Vienna, in the imperial treasury, there is another Gospel book in similar style, which, legend says, was found on the knees of the Emperor when his tomb was opened.