The Ljubljanica River is famous for winding its way through Slovenia’s capital, and for appearing and disappearing several times as it flows down from the Karst Plateau. Few realize, however, that it also plays a role in the famous legend of Jason and the Argonauts.

According to the story, Jason and his crew boarded the ship named Argo in order to capture the fleece from the golden lamb. The Argonauts were successful in their endeavor, but when retreating from a Black Sea port, they mistakenly made their way up the Danube. They followed the course of the Danube into the Sava until they reached the Ljubljanica, a small tributary.

The legend is even mentioned by Pliny, the Roman historian, who refers to the present-day town of Vrhnika, just outside of Ljubljana, as being founded by the Argonauts. Locals even point to physical evidence of Jason’s visit: A crack in a large rock above the source of the Ljubljanica River. The legend recounts that the Argonauts encountered the rocks of Močilnik in a horrific storm. In order to save the ship, Jason hit a large rock with his fist, forming a large hole. His arm acted like an anchor, preventing the ship from being shattered in the tempest. After the storm, Jason is said to have carried the Argo all the way to the Adriatic Sea and safety. As unbelievable as it sounds, the story has some basis in reality: In times past, boats were frequently portaged from the Ljubljanica to the Adriatic.

There is another reminder of the legendary visit by Jason and his Argonauts: When sailing on the Ljubljanica, Jason was also said to have battled fierce dragons that were determined to prevent his passage. He defeated the beats and according to the legend, his encounter gave rise to the dragon as a symbol of Ljubljana. Dragons are now featured on the city’s coat-of-arms and guard the Dragon Bridge, a well-known landmark in the very heart of Slovenia’s capital.

Vrhnika, meanwhile, organizes Argunaut Days each June in honor of the town’s ancient founders.