West exterior of the Mausoleum of Galla Placidia, with visitors showing its scale. (For a similar view without people, see image xti_6508b.jpg.) The mausoleum has sunk 4.5 feet into the ground sinc its construction in c.430 AD. Shaped like a Greek cross and covered with magnificent Byzantine mosaics inside, it was probably built as an oratory rather than a mausoleum. Galla Placidia, a powerful Roman empress, was never buried here but probably commissioned the building.