(b Constantinople, c.ad 388 or 393; d Rome, 450).
Late Roman empress and patron. She was the daughter of Theodosius I the Great and half-sister to the Emperor Honorius (reg 395–425). She was brought up in Constantinople and Rome, from where she was taken hostage by the Visigoths during the sack of 410, and was married to their leader Athaulf in 414. On his death the following year, she was returned to her own people and in 417 reluctantly married her brother’s Master of Armies, who was to become Constantius III (reg 421). After quarrelling with Honorius, she fled to Constantinople, but on his death her son Valentinian III (reg 425–55) was installed as Emperor in the West by the eastern armies. At first her influence was dominant, but she was unable to stop the increasing power of Aetius (c. 391–454), and by 438 she had been forced into virtual retirement.
Placidia’s building works reflect the piety she apparently gained while in exile in Constantinople. In Rome she commissioned the mosaics in S Paolo fuori le mura, of which only one piece survives, though much restored, above the triumphal arch. Her preference, however, was for the new court city at Ravenna, which she adorned with several ecclesiastical buildings. One building to have survived intact is the so-called Mausoleum of Galla Placidia (...