The Aula Palatina, also called Basilica of Constantine, at Trier, Germany, is a Roman palace basilica and an early Christian structure built between AD 300 and 310 during the reigns of Constantius Chlorus and Constantine the Great. Today it is used as the Church of the Redeemer and owned by a congregation within the Evangelical Church in the Rhineland. The basilica contains the largest extant hall from antiquity. Wikipedia