The castle was built around 1500 above the gorge of the River Dobra – Đula’s Abyss. The founder of the town was Bernardin Frankopan, one of the most powerful noblemen of his time and the feudal master of Modruš, Plaško, Vitunj, Tounj, Zvečaj, Bosiljevo, Novigrad and Dubovac.
It belongs to the period of Renaissance castles. The town walls surround the courtyard area on three sides, while on the fourth there is a three-storey building with towers at the edges. Its military significance and the position of the town of Ogulin required a well-fortified structure.
Today, the castle houses The County Museum opened in 1967. It owns several collections showing exhibits of various kinds: archaeology, ethnology, old armaments, a memorial room for Ivana Brlić-Mažuranić (a renowned Croatian fairy-tale author), mountaineering, and an exhibition of the academic painter Stjepan Galetić born in Ogulin who donated 200 of his artefacts to the museum.