The Arian Baptistery is thought to have been built by Theodoric the Great, King of the Ostrogoths, between 493 and 526 AD. The centrally planned, octagonal building is topped with a dome covered with a precious mosaic, depicting the procession of the apostles and the baptism of Christ. This contrasts with the bare internal brick walls. The Baptistery received UNESCO World Heritage status in 1996.

In 2013, the Municipality of Ravenna redesigned the lighting for the dome, using Pivot projectors and alternating the cool colour and warm colour versions to ensure that all the original shades of colour were returned to the mosaic