After the conquest and up to the Marcomannic Wars in 166/180 AD the Upper Danube area with the provinces of Raetia and Noricum were rather peaceful frontier zones. There was no need for the presence of larger elite troops, Rome´s legions. The political situation changed rapidly, after Germanic tribes had raided the territories of these provinces. The army command decided to reinforce both frontier lines with 12.000 soldiers in two legionary fortresses. The one in Raetia was built in Regensburg, the other on a strategically important spot in the center of Noricum close to the confluence of the Enns and the Danube. The building force and garrison in place for a long time was the Legio II Italica.
With the establishment of the legionary fortress the former small-sized civil settlement started to flourish and transformed into a large, prosperous town with luxury living quarters and a lively scenery of craftsmen, workshops, merchants and public houses. The life of Florian demonstrates that when Aquilinus became administrative governor in Noricum around 300 AD, there was already a Christian community operating in Enns. The Vita Sancti Severini tells us about a bishop Constantius, who organised the defense of Enns in 476 AD shortly before the place was given up by the Romanized population to the Barbarian invaders.
The former Town Hall on the main square today houses the Lauriacum Museum dedicated to the Roman history of Enns. It offers a truly fascinating and educational experience with many artifacts recovered from archaeological excavations, especially a part of the very large building inscription of the legionary fortress from 205 AD and a beautiful wall painting depicting Amor and Psyche. The museum is also home to the Old Enns Gallery, a weaponry collection hall, a memorial room commemorating the Georgenberg Handfeste of 1186, and memorabilia of famous citizens of Enns.