I hope it was only used for worship during the better weather
.
The Free Church over here used to use natural hollowed out features when the church split (1843 ) before they started to build churches.
edit, I like the Famine wall, a nice bit of wall, unusual style, or are they all like that in Ireland ie the bottom part being different from the top section.
Edited: 16/04/2012 at 20:58