Claudium Virunum was a Roman city in the province of Noricum, on today's Zollfeld in the Austrian State of Carinthia. Virunum was founded under Emperor Claudius as the capital of the province of Noricum. The new Roman foundation was situated on the main route from the Adriatic to the Danube, with a branch through south eastern Carinthia connecting Virunum with the Amber Road.
From AD 343 Virunum is known to have been a bishop's see. Little is known about the decline of the city. Being unfortified and situated in a flat valley, during the Migration Period the city was probably partly or totally evacuated by its inhabitants, who left for the surrounding hills such as Ulrichsberg or Grazerkogel.
The city proper covered an area of about 1 km². Extensive and systematic excavations took place from end of the 19th century until 1931. Further excavations were not undertaken until the end of the 20th century culminating in the excavation of the amphitheatre.
Apart from the city capitol, a Dolichenum for the military god Jupiter Dolichenus was excavated, inscriptions have been discovered proving the existence of two Mithraea, and in 1999 two votive relief plates were found from a Nemesis temple near the amphitheatre. Proof of an early Christian church, whose existence had been presumed for a long time, has recently been found in the northern section of the city.
A proper Roman theatre with a stage, the only one known in all Noricum, as well as elliptic amphitheatre were situated on the slope of Töltschach Hill. A large building further east is believed to have been the palace of the Praeses or provincial governor.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.