The Ljubljanica (pronounced [ljuˈbljaːnitsa]), known in the Middle Ages as the Ljubija, is a river in the southern part of the Ljubljana Basin in Slovenia. The capital of Slovenia, Ljubljana, lies on the river. The Ljubljanica rises south of the town of Vrhnika and outflows in the Sava River about 10 kilometres (6.2 mi) downstream from Ljubljana. Its largest affluent is the Mali Graben Canal. Including its source affluent the Little Ljubljanica (Slovene: Mala Ljubljanica), the river is 41 km (25 mi) in length. The Little Ljubljanica joins the Big Ljubljanica (Slovene: Velika Ljubljanica) after 1,300 m (4,300 ft) and the river continues its course as the Ljubljanica.
The Ljubljanica is the continuation of several karst rivers that flow from the Prezid Karst Field (Slovene: Prezidsko polje) to Vrhnika on the surface and underground in caves, and so the river is poetically said to have seven names (six name changes): Trbuhovica, Obrh, Stržen, Rak, Pivka, Unica, and Ljubljanica.
The Ljubljanica has become a popular site for archaeologists and treasure hunters to dive for lost relics and artifacts. Locations in the river between Ljubljana and Vrhnika have offered up pieces of history from the Stone Age to the Renaissance, belonging to a variety of groups, from local ancient cultures to more well-known groups like the Romans and the Celts. One of the more significant findings is a yew spearhead, found in 2009 in Sinja Gorica. It has been dated to about 35,000 to 45,000 before present, the Szeletien period, and supplements the scant data about the presence of Stone Age hunters in the Ljubljana Marshes area.