My roommate is playing the most gorgeous church music in the world; and it isn't Latin. It's Byzantine choral music in Old Slavonic. To hear Church Slavonic sung with the Russian pronunciation from the Liturgy of St. John Chrysostom is one of the most deeply sacred experiences on the planet. It almost brings tears to the eyes. Everybody has their favorite Rome memory. The best Rome memory I have is the cold winter nights when in the dark, tired and hungry, I crawled up the steps to the Rvssicvm to hear vespers chanted in an empty church on a Saturday night.
N.B. Modern man is so blasé so as to not even recognize the beauty of this music, but if you're ever in Rome on a cold winter Saturday night, then be sure to attend vespers at the Rvssicvm.