Open Culture:

If you don’t happen to live near a cathedral, you can experience something of that atmosphere through your headphones anywhere you happen to be with Callixtus, a channel on the not normally sacred space of Youtube.

“Perhaps named in honor of either Pope Callistus or Xanothopoulos Callistus, Patriarch of Constantinople,” writes Catholic web site Aleteia’s Daniel Esparza, it offers “an impressive collection of sacred music, mostly medieval, including choral works belonging to both Western Christianity and the Eastern tradition.”

I’m not the least bit religious but I love listening to these chants.