Carnuntum, most important ancient Roman settlement in Austria. Situated in the area between present-day Petronell-Carnuntum and Bad Deutsch-Altenburg (Lower Austria). The name C. was taken over from a pre-Roman settlement. C. is mentioned in the works of Velleius Paterculus, Pliny the Elder, the astronomer Ptolemaios, in the "Meditations" of Emperor Marcus Aurelius (the 3rd book of which he wrote at C.), in the vita of Septimius Severus, in the works of Ammianus Marcellinus and many other texts of late Antiquity, the Tabula Peutingeriana, Itinerarium Antonini and the Notitia Dignitatum. The oldest archaeological finds from the area of the military camp date from the middle of the 1st century A.D. The civilian town of C. became the capital of the province under Emperor Trajan (98-117 A.D.) (Pannonia) as well as seat of the governor; Emperor Hadrian (117-138 A.D.) made it an independent town, Municipium Aelium C., and Emperor Septimius Severus (193-211 A.D.), who was proclaimed emperor at C., gave it the status of a Colonia. In late Antiquity a legion and a Danube fleet were stationed at C. and an emperors conference was held there 307 or 308 A.D. Around 350 A.D. an earthquake caused serious damage and marked the beginning its decline. Under Emperor Valentinian I Carnuntum served as headquarters in the war against the Quadi and Sarmatians in 375.
The military camp was situated between today's Petronell and Bad Deutsch-Altenburg, in the shape of an irregular polygon 490 m in length and between 334 m and 391 m in width, its front side, which faced the Danube, has been swept away by the river. To the west lies a minor camp for supporting troops. The town situated before the camp (canabae legionis) had its own forum, thermal baths and an amphitheatre for 8,000 people; a temple district where oriental deities were worshipped was discovered during the excavation works.
The large thermal baths were what is now called the palace ruin, which was adapted for representative purposes around 300. The amphitheatre close to the Heidentor had a seating capacity of 13,000. The hypothesis claiming that the buildings at the southern portal were an early Christian church and baptistry remains unproven. Today two Roman aqueducts still carry water; they were made of bricks and it was even possible to walk in them. A temple district for the Roman state cult, monuments for the worship of the emperors Hadrian and Marcus Aurelius, a cult theatre, numerous altars and inscriptions were built on top of the Pfaffenberg hill. Finds are exhibited in the newly designed Museum Carnuntinum; archaeological park; Festival Art Carnuntum.