Reference was made to an ivory throne brought from Alexandria to Constantinople by Heraklius (610-641). This throne was ultimately placed in the Cathedral at Grado, and the legend grew up that it was actually the episcopal throne of St. Mark, who was the first Bishop of Alexandria. In the Castello at Milan there are a series of five plaques dealing with the subject of St. Mark’s mission to Alexandria and Cyrene, as told in the Acts of St. Mark; there is every probability that they belonged to the throne of St. Mark in Grado, which appears to have been more or less perfect in the sixteenth century, but is reported by a later writer to be entirely stripped of its decoration. The Milan reliefs are of a very distinctive technique, the drapery being marked by rib-like folds, usually in couples, and the type of face is refined, though over elaborated. They are earlier than the time of Heraklius, and probably date from the sixth century. Three scattered plaques are unmistakably connected with this series; _St. Peter dictating the Gospel of St. Mark_, with a winged figure behind, in the Victoria and Albert Museum; _The Raising of Lazarus_ in the British Museum, and _The Annunciation_, in the Trivulzio Collection at Milan. The two last are more delicately carved, but the striking similarities of pose and drapery, and the same violent perspective of the architecture, make it almost certain that they are from the same _atelier_, if not by the hand of the same craftsman. Two ivories of a totally different style seem to belong to the next century, but their dates are still a matter of doubt. One is a plaque in the Treasury of Trèves Cathedral, deeply undercut and full of little figures and details. Westwood says it represents the arrival of the Holy Coat to that very Cathedral.[13] The relic is in a casket held by two ecclesiastics, who sit in a gorgeous car drawn by a pair of horses. The procession is led by the Emperor Constantine and received at the church doors by his mother, Helena, who holds a cross in memorial of her journey to Jerusalem to fetch the True Cross. In the background is the Porta Nigra, and the nave of a basilica showing an apse. Unfortunately, there is no proof of this attractive theory, though the building in the background does resemble the Porta Nigra (still existing at Trèves) and the basilica there has a very similar apse; but all Roman architecture imperfectly depicted looks much alike, every basilica has an apse, and it is not recorded how long the ivory has been in the Treasury at Trèves. Thus we must be reconciled to call it by an indeterminate name. It is certainly Byzantine, and most probably about the seventh century.