Holy Cave, Sacred cave near San Servolo village, Slovenia

Holy Cave is a karst cave near Socerb, just below Socerb Castle. It is 231 metres long and 44 metres deep, with a large entrance hall that holds Slovenia's only underground church and some side passages. The entrance is closed by a gate.

A saint named Servulus sought refuge here in the 3rd century and lived as a hermit within the cave. His presence transformed the place into a religious shrine that people have honored ever since.

The cave's name comes from Saint Servulus, a young martyr executed by the governor of Trieste in 283 or 284. Until World War II a Mass was held here every 24 May, his feast day, making the cave a pilgrimage site. The entrance hall holds Slovenia's only underground church.

The cave lies on the road up to Socerb Castle, just above the village of Socerb near the Italian border. The entrance is closed by a gate, and the cave is managed by the Dimnice caving society, which opens it for visits on Sundays at 2 pm.

The cave lies just below Socerb Castle, a short walk from the Italo-Slovenian border near Prebenico. San Servolo is a co-patron saint of Trieste, and the castle above did not yet exist during his martyrdom in 284.