One of the most beautiful such churches is Saint Sophia in the Cave, in Mylopotamos, Kythera. I saw the posters all over the storefronts of the island but couldn't fathom from the faint photo what to expect.
The impossible blue of the sea is often part of the surrounding scape.
When we arrived on the site of several parked pars on the road, we realized this had to be it. We saw the entrance over the side of the cliff and took a look. A long pathway had been built into the cliff that led to the cave.
Above are closeups and details of various saints depicted on the templon.
This is one of the most spectacular caves I've ever seen, not because it is huge or grand but because it has not been significantly altered. The history of the church in the cave is intriguing and the temple that I saw when I first entered the cave created a feeling of mystery and a connection with history.