With most historical figures one can say 'X died today in year y' and then one can highlight a few interesting things from their life. What's cool about Galla Placidia is that we have her mausoleum preserved in Ravenna. I've heard stories that her mummified body survived into the Renaissance, seated in full costume and regalia, until someone inserted a taper and it went poof ... but have not yet been able to track down a source, so the story might be apocryphal.
Aelia Galla Placidia was born in 392 or 388 or 390 ... and died on the 27th November AD 450.
The daughter of Theodosius I, she was brought up by her cousin Serena and her husband Stilichio (shown in this ivory diptych in Monza). Later she was given her own household in Milan. Galla Placidia was betrothed to Serena and Stilichio's son Eucherius, but both men were executed in 408 so that didn't work out.
Between 408 and 410 she was in Rome whilst it was being besieged by Alaric. Serena was accused of complicity with the Visigoths, and executed with the consent of Galla Placidia and the entire Senate according to Zosimus. Alaric took and sacked Rome in AD 410 - the first time the city had fallen to foreign invaders since the Gauls in 390 BC. Galla Placidia herself was captured, though the sources are a little unclear whether this was on August 24th when the city fell, or if she was already Alaric's prisoner by then. They took her with them as they marched back up through Italy and into Gaul.
Alaric had died in Calabria, and was succeeded by his half-brother Ataulf as king of the Visigoths in 410. Honorius - panicking - decided that the best thing would be a peace treaty cemented by a royal marriage between his sister and Ataulf, so Galla Placidia married him on New Year's Day 414 in Narbonne. At the end of the year their only son Theodosius was born in Barcelona (d. 415 - his body was later moved to St. Peter's in Rome). In late summer of 415 Ataulf was murdered in his bath, Galla Placidia became a widow - and was mistreated by his successor.
Galla Placidia returned to Italy under the terms of a peace treaty, and in 417 was made to marry the magister militum who would become Constantius III (briefly in 421, the year he died). Their son eventually became Valentinian III; their daughter, Justa Grata Honoria, is the one who sent a letter proposing marriage to Attila the Hun, which he in turn used as the excuse to invade Italy in 451.
As a widow Galla Placidia was accused of incest with her half-brother Honorius - and exiled with her children to Constantinople. Honorius died in 423, and her son (b. 419) became Valentinian III first as Caesar then as Emperor of the West in 425. Galla Placidia was his regent until 437.
Many interesting churches can be assigned to her either as builder or restorer, but my favorite is her Mausoleum which may originally have been built as a church of St. Lawrence. And technically, we're not sure if it ever housed her remains.
Photos pinched off Wiki off the great mosaics.
This image is probably a copy of the famous Hellenistic mosaic by Sosus of Pergamon - apparently the original was so life-like that real birds flew up to it and tried to drink from the water.
Full view of the scene it came from with two togate men - this would have been an historical anocronism by the time the scene was created.
Isn't this the most amazing ceiling.