For Sunday, here's Felix Mendelssohn's "Ave Maria," which is as gorgeous (and as relatively unknown) as you might expect if you've been fortunate enough to stumble across his surprisingly-unfamous choral efforts at any time in the past. (We need to find someone who will do for Mendelssohn what he did for Bach. Also, playlist.)
Attribution(s): "Bell Tower" (source) via CC BY-SA 4.0.