View from southwest of the Mausoleum of Galla Placidia. The small brick structure dates from around 430 AD, making it one of the oldest monuments in Ravenna. It has sunk 4.5 feet since its construction. Shaped like a Latin 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.