Nauportus , ancient Roman town in Pannonia Superior (later 10th Italian region) on road from Aquileia

Aquileia

Aquileia is an ancient Roman city in what is now Italy, at the head of the Adriatic at the edge of the lagoons, about 10 km from the sea, on the river Natiso , the course of which has changed somewhat since Roman times...

 to Emona

Emona

Emona or Aemona, short for Colonia Iulia emona, was a Roman castrum founded in 14-15 AD, possibly by the Legio XV Apollinaris , on a territory already populated by ancient settlers of uncertain origin...

 with port at Nauportus river what is now Ljubljanica River

Ljubljanica

The Ljubljanica is a river in the southern part of Ljubljana Basin in Slovenia. The capital of Slovenia, Ljubljana, is situated on the river. The Ljubljanica rises to the south of the town Vrhnika and outflows in the Sava River about downstream from Ljubljana. Its largest affluent is Mali graben....

.

According to historian Pliny the Elder

Pliny the Elder

Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

 the name was derived from the legendary landing of the Argonauts

Argonauts

The Argonauts ) were a band of heroes in Greek mythology who, in the years before the Trojan War, accompanied Jason to Colchis in his quest to find the Golden Fleece. Their name comes from their ship, the Argo, which was named after its builder, Argus. "Argonauts", therefore, literally means...

 at river, where they are said to have founded the town.

Tacitus

Tacitus

Publius Cornelius Tacitus was a senator and a historian of the Roman Empire. The surviving portions of his two major works—the Annals and the Histories—examine the reigns of the Roman Emperors Tiberius, Claudius, Nero and those who reigned in the Year of the Four Emperors...

 reports that in year 14 town was plundered by mutinous roman forces

Legio I Germanica

Legio I Germanica was a Roman legion, possibly levied in 48 BC by Julius Caesar to fight for him in the civil war against Pompey...

 that has been sent to build roads and bridges.

Remains of Nauportus what is today Vrhnika

Vrhnika

Vrhnika is a town and a municipality in Slovenia. It is situated on the Ljubljanica River, 21 km from Ljubljana along the A1 motorway.-History:...

, Slovenia were found. An Late Roman emporium with warehouses and a central market was located and excavated at river banks. Traces of Claustra Alpium Iuliarum

Claustra Alpium Iuliarum

Claustra Alpium Iuliarum was a defense system within the Roman Empire between Italia and Pannonia that protected Italy from possible invasions from the East. It secured the Postojna Gate, the land link between the eastern and western part of the empire, and thus the Claustra represented an inner...

system and of guarding tower and Late Roman castellum can be seen in Vrhnika and its vicinity.