To give some idea of the narrow aspect of the columns I recall in that unknown church in the Middle Ages, I found a good reference to columns that look kind of similar:
These are at the Benedictine abbey in Moissac, France. I do know that these columns are not the ones I saw as these are in the cloister; the columns I remember ran along the aisle next to the Nave, and did not run to the floor but came to a low screen or fence-type divider with a few doorways in between. Also, they were black; whether this was black stone or stone painted to appear black, I am not sure.
Still, the image should give some idea of the narrow aspect of the columns I remember, and might help jog someone’s memory if the place still exists. Personally, I’m doubtful that the place was real and if it was, I’m doubtful it still stands in a form I would recognize, but you never know.