The Ljubljanica, known in the Middle Ages as the Leybach, 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 flows into 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, the river is 41 km (25 mi) in length. The Little Ljubljanica joins the Big Ljubljanica after 1,300 m (4,300 ft) and the river continues its course as the Ljubljanica.

Ljubljana is the capital and largest city of Slovenia, located along a trade route between the northern Adriatic Sea and the Danube region, north of the country's largest marsh, inhabited since prehistoric times. It is the country's cultural, educational, economic, political and administrative center.