Burgruine Liebenfels is a pair of castle ruins on a rocky hilltop northeast of the municipality of Liebenfels in the district of Sankt Veit an der Glan, the historical central area of Carinthia, Austria.

The surviving structures include examples of Romanesque, Gothic and Renaissance architecture.

There are two massive keeps, from around 1300 and the early 14th century respectively, one in the stronghold and one in the extensive outer Bailey.

The complex is surrounded by an early Gothic ring wall with battlements that have been preserved.

To the north of the chapel is another Gothic residential building with stepped gables and evidence of a heated room and the characteristic room windows that can already be observed in the keep and the great hall structure.