Some Helpful Resources
An official of the National Monuments Service shared these instructions for locating Mass Rocks, Mass Houses, Monastic Sites, etc
This will load up our viewer. You will see a series of icons on the right hand side of your screen, just above the map. Of these icons the leftmost of which looks like a funnel. You click on that and then pick your county. You go down to class and type in mass. You will be confronted by four choices, Penal Mass Station, Mass Rock, Mass Rock (present location) and Mass House. You will be picking two of those categories.
I chose Tipperary North and there are 11 mass rocks in the County (see attached file Mass Rock 1). Some counties have descriptions with them, others do not, either way you can come here to Dublin to view the files. You can clear your query and try Mass Rock (present location) this is to describe any Mass Rocks that might have been taken into churches or local museums. In the case of Tipperary North there are no such records. In Cork there are two (see attached file Mass Rock 2). There is a facility to copy your results into a spreadsheet, this contains the County, Class, Townland, ITM coordinates and Irish Grid Coordinates.
If you do need to come to Dublin to see the files you can reply to me and I will pass your message on. When sending a list of files you need to see the most important thing is the file number which looks like this CO084-108---- or CO084001- this is required in order to retrieve the record.
I hope this has been of some help."
"Mass Rock", "Mass Houses", "Monastic Ruins", etc Putting these terms in google bring up many more locations