[3][4] The fortress complex consists of three parts connected by walls: the town with its castle-town (in Serbo-Croatian: podgrađe), Tabor and Ljubica (Lubica) towers.

In the Late Middle Ages, a unique territorial-political unit was formed as the župa of Sanica, in which Ključ was a seat.

In 1364, Vlatko ceded the fortress to the Hungarian king Louis I in exchange for possessions in Hungary, namely Slavonian town Bršljanovac.

[7] The town with its castle-town is mentioned in the charter of King Stjepan Tomaš in issued in Vranduk in 1446, when he confirmed the possession of Ključ to Ivaniš Dragišić and his sons.

Although the town of Ključ has been known for 120 years at the time, only in this charter of King Tomaš is the castle-town mentioned by name of Podključ.

In the first years, the town was the gathering place of the Ottoman army for further conquests towards Bihać and the Croatian-Austro-Hungarian territories.