The town, called Jülich today, was situated east of the crossing of a small river, the Rur (which is not to be confused with the Ruhr), and there must have been a bridge. A tile from Sixth legion Victrix proves that soldiers guarded the river crossing. The inscription can be dated after the arrival of this unit to suppress the Batavian revolt (in 70) and before 121, when it was transferred to Britain.Iuliacum is mentioned on the Peutinger map, which means that it was a settlement of some significance in the fourth century. This is confirmed by the archaeological record, which shows that at the beginning of the fourth century, Iuliacum was fortified with a mighty, fourteen-sided wall. According to the Roman historian Ammianus Marcellinus.note[Ammianus Marcellinus, Roman History 17.2.1.] the castle was still in use in 357, when the area was plundered by a large group of Frankish cavalry. The fort may have been used for an additional half century.
Among the archaeological finds from ancient Iuliacum is a fine statue of Jupiter, seated on his throne, made of sandstone. Stylistically, it can be dated to the first quarter of the third century. Once, it must have graced a column in the court of a villa.