An aula regia (lat. for "royal hall"), also referred to as a palas hall, is a name given to the great hall in an imperial (or governor's) palace in the Ancient Roman architecture and in the derived medieval audience halls of emperors, kings or bishops as part of their palaces (for example the German Kaiserpfalz – Imperial palace). In the Middle Ages the term was also used as a synonym for the Pfalz (palace) itself.
Architecturally, the medieval aulas followed the model of the ancient Roman audience halls in the imperial and governor's palaces such as the Aula regia in the Flavian Palace on the Palatine Hill in Rome, completed in 92Â AD or the Aula Palatina in Trier, Germany, completed in 311 under Constantine the Great. This emperors's mother Helena lived in Rome in the Sessorium Palace; She had its smaller, hall-shaped aula converted into the church of Santa Croce in Gerusalemme for the relics she had brought with her from Jerusalem, while of the palace's larger civil basilica, built in the style of a three-aisled columned basilica, only the apse remains as a free-standing ruin.