Mausoleum of Galla Placidia; Ravenna. Named after the half-sister of the Byzantine Emperor Honorius (AD 384-423) - though probably never holding her remains - who played a dominant role in the early days of Byzantine Ravenna. The mosaics are an earlier style than in the nearby Basilica di St. Vitale. Picture shows an internal roof mosaic depicting Christ's monogram; the chi-ro symbol.. Country of Origin : Italy Culture: Byzantine Date/Period: 5th C AD. Place of Origin: Ravenna. Credit Line: Werner Forman Archive/ N. J. Saunders