There is a spiritual aura in the Patmos Cave in there that is palpable.  Within its dark confines, the Apostle John wrote the Book of Revelation.

A Greek Orthodox monastery has been built around the cave, and the monks hold prayer vigils in the cave twice a day.

During other times of the day, visitors are free to enter the cave and look around.  No photos are allowed in the cave or monastery, but my photograph is a view of the entrance of the monastery.

This is the exact spot where you would have greeted the Apostle John when he came out of the cave. As you would surmise, the icon above the door is John.

The monastery is aptly named the Monastery of St. John, and the cave itself is called the Grotto of the Apocalypse.