St. Peter supposedly preached in this cave, and who am I to doubt that?
The early Gothic facade was erected by the Crusaders (restored in 1863). The interior was transformed into a three aisle church. Some remains of a mosaic floor are fifth century. To the left of the altar is a - now caved-in, tunnel early Christians would use to flee in case the authorities were after them. To the right of the altar is a font with water dripping down the rocks that is supposedly medicinal. It sued to be called for paptisms. A notice inside indicates that Pope Paul VI paid the place a visit and promised a plenary indulgence to whoever came here. My Roman Catholic uncle later explained me that was for Catholics only. What a pity, I had felt so relieved..
The entrance to the tunnel can be seen here.