Take a tour of Predjama Castle in Slovenia - part of the World s Greatest Attractions series by GeoBeats. Part castle, part cave, Predjama Castle is the ultimate stronghold hideout. The most famous owner of the castle was the knight Erazem Lueger in the 15th century. He became an enemy of the Holy Roman Empire over an insult by an Imperial Commander to his dead friend. Fleeing to his castle home, he survived a siege using secret cave tunnels.