A long time ago, the Greek hero Jason and his companions from the ship Argo stole the Golden Fleece from the Colchian king. In an effort to escape its pursuers the ship took a wrong turn and, instead of sailing south along the Aegean Sea, found its way to the mouth of the Danube river. As there was no way back for them, they continued up the Danube, the Sava and eventually the Ljubljanica. At the source of the Ljubljanica they stopped, took the ship apart, put the pieces on their shoulders and literally carried the ship to the Adriatic sea where they reassembled it and continued on their way home. Between the present-day Vrhnika and Ljubljana the Argonauts found a big lake surrounded by a marsh. It was here that Jason came across a terrible marsh monster, which he fought and killed. This monster was the Ljubljana dragon, which today finds its permanent home on top of the castle tower in Ljubljana’s coat of arms.

Source: http://www.ljubljana-tourism.si