CARNUNTUM, an ancient town in Upper Pannonia, on the right bank of the Danube It was of Celtic foundation, but became at a somewhat early period a Roman post, and was raised to the rank of a colony and a municipium. For three years during his wars with the Marcomanni and Quadi it was the residence of Marcus Aurelius, and here a part of his Meditations was composed. The town was taken and destroyed by the German invaders in the 4th century; but it was afterwards rebuilt, and continued to be a place of some importance till its final destruction in the wars against the Magyars in the Middle Ages. Extensive ruins, supposed to be those of Carnuntum, still exist at Hainburg or Haimburg, a small town of Lower Austria, about 24 miles east of Vienna.