Emona or Aemona (short for ) was a Roman castrum, settled by colonists from the northern part of Roman Italy. Emona itself was the region's easternmost city, although it was assumed formerly that it was part of the Pannonia or Illyricum, but archaeological findings from 2008 proved otherwise. It was located in the area where the navigable Ljubljanica came closest to Castle Hill. The river played an important role as a transport route for the trade between the city and the rest of Roman empire. From the late 4th to the late 6th century, Emona was the seat of a bishopric that had intensive contacts with the ecclesiastical circle of Milan, reflected in the architecture of the early Christian complex along Erjavec Street in present-day Ljubljana.