Predjama Castle is a medieval fortress built into the mouth of a cave in southwestern Slovenia. The castle was first mentioned in historical records in 1274 and has been expanded and renovated over the centuries. The castle's location in the middle of a cliff face makes it unique, and it has been the subject of many legends and stories over the years.

Predjama Castle was built by the Patriarch of Aquileia in the 13th century and was later owned by the Luegg and Cobenzl families. In the 16th century, the castle was purchased by the famous knight Erazem Predjamski, who used it as his base for raids on nearby towns. He held out against the Austrian army for over a year until he was finally betrayed and killed in 1484.

The castle was expanded and renovated in the 16th and 17th centuries, and it has been used for various purposes over the years, including as a prison and as a museum. Today, it is one of Slovenia's most popular tourist attractions, and visitors can explore the castle's many rooms and passages, including a chapel, a dungeon, and a great hall. The castle also houses a museum dedicated to Erazem Predjamski and his life and exploits.