Situated just a few kilometres from the entrance to Postojna Cave stands one of the most picturesque buildings in the whole of Slovenia. Construction of Predjama Castle was probably began in the 13th century; it is first mentioned in the mid 14th century as castrum Lafcram and carsis positum, which means 'Cave Castle in the Karst'. In that period the patriarchs of Aquileia invested various knights with the castle and property. When the power of the Aquileian patriarchs declined, the castle was seized by the Habsburgs, who also invested various vassals with it. The first Slovene associated with the castle was A Konrad, burgravio di Jama, who is mentioned in 1397. In 1478 Emperor Frederick III invested Erasmus Lueger, whom Slovene historians call Erasmus of Predjama, with the castle. Then in 1567 Austrian Archduke Karel invested Ivan Kobencl from Prosek with the 'Jama' manor. At that time the castle was in a very poor condition, so the new lord renovated it in Renaissance style. The last Kobencl bequeathed Predjama Castle to his relative, Count Mihael Coronini from Kromberk, whose wife sold the fortress to Prince Weriand Windischgrätz in 1846. Thereafter it remained in hands of the Windischgrätz family until 1945, when it was nationalised.

In recent decades Predjama Castle has been managed by the Notranjska Museum, Postojna. Since the late 1990s the castle has been under renovation with the aim of restoring it to how it would have looked in the time of Ivan Kobenci, a period when castles were steadily losing their defensive function.

A centuries-old linden stands in front of the castle and legend has it that Erasmus of Predjama is buried underneath it. The small Gothic church in front of the castle was recently renovated; its main attractions are frescoes from the 15th century and a Baroque altar.