St Govan's Chapel is in Pembrokeshire, South Wales. It was built into the edge of a cliff in the 14th century and is named after a hermit who died in the 5th or 6th century. According to local legend, St Govan hid from pirates in the crack in the cliff face. When you enter the chapel, you can see an imprint resembling a ribcage in the cliff wall.
It is a special place to visit, not least because you have to drive through an army firing range to reach the car park, and then climb down 50 or so steep stone steps (another legend says the number of steps is never the same when you count them walking down and climbing up!)