The grandiose fresco in the apse represents the most spectacular testimony of the interventions desired by Patriarch Poppone, who radically restored the Basilica after the earthquake of 988.
An almond with the Virgin and Jesus enthroned dominates the scene from above, surrounded by the symbols of the Evangelists. The saints of the Aquileian tradition pay homage to them: Ermacora (the first bishop), Fortunato and Eufemia on the right, Marco, Ilario and Taziano on the left.
In the group we recognize the characters of the imperial house and Poppone himself, who brings a model of the Basilica as a gift to the Virgin. Lower down, the long procession of martyrs is depicted in a frontal position on the sides of the window, while the lower register is decorated with imitation marble panels and a band of spiral tendrils populated with birds.
Made between 1028 and 1031, the work represents a unicum in northern Italy of the 11th century.