I keep listening to this over and over again. I just cannot get past how incredibly beautiful and haunting is:
Praise the Lord O My My Soul (Greek Chant)
Vespers (All-Night Vigil), for alto, tenor & chorus, Op. 37
Composed by Sergey Rachmaninov
Sung by the USSR Ministry of Culture Chamber Choir with Irina Arkhipova
Unbelievable, particularly Irina Arkhipova and those who sing the Basso Profondo part!