I watched The Sound of Music last night for the first time in years- so fantastic! Anyway, I was just bowled over by this music which was sung by the nuns near the beginning.
I could listen to this kind of a cappella music all day every day. Were these “nuns” a real singing group? Is there a collection out there of this kind of music?
There are nuns that form singing groups, see for instance http://www.singingnuns.com/ . They sing plenty of modern hymns and songs. If you’re looking more for the a capella, older sacred music style, try searching for “nuns” and “chant” (e.g. this). Although if you want something more like the Sound of Music piece itself, you may need to look for something more modern (I mean like 4 or 5 centuries old instead of 6 or more). This may be more to your liking.