This large marble slab, which is carved on both sides, is decorated with two orders of arcades and bands with a stylised palmette motif.
It is quite probably a fragment of the choir screen from the ancient basilica of San Salvatore in Turin, dating from the time of the iconoclast Bishop Claudio (816-827). The building was demolished in 1490 to make way for the construction of the new cathedral of San Giovanni, but some of the marble items were saved by the humanist Filippo Vagnone, who moved them to his residence in Castelvecchio di Testona. Some fragments of the furnishings of the three previous basilicas, which are now in the Museo di Antichità in Turin as well as in Palazzo Madama, were unearthed during archaeological excavations in 1909.