The most haunting music you ever heard?

I listened to the acoustic version of "Under the Milky Way" from the band "The Church". I can only describe it as haunting. Jokes aside, which might be too much to ask :-), what is the most haunting music/song or cd you have heard?
Check out the album "The Swell Season" by Glen Hansard and Markéta Irglová. The album includes studio versions of many of the songs from the soundtrack of the movie "Once". The mostly (entirely?) acoustic album is some of the most beautiful and haunting song writing, singing and playing I have heard all in one place in a long time. For audiophiles, I think "The Swell Season" has higher production values than the soundtrack, although the play lists are slightly different. You might want to watch the movie before buying either CD.
''Reunited'' by Peaches and Cream. OK that's a bad joke. For me, ''Cavatina'' from the movie The Deerhunter if pretty haunting. A few more can be heard on the Cd ,''John Williams plays the Movies''.

There's something about movie themes and music that I find mysterious and engaging at the same time.
What about Fantasia on a Theme of Thomas Tallis?

FWIW I concur with the Acoustic "Under the Milky Way" I have it,its lovely.

Check out the Bax Quintet for Harp and Strings,Elegiac Trio for Harp and Violin Fantasy Sonata for Harp and Viola and Sonata for Flute and Harp by Mobius on a Naxos CD .
Anything by Genesis after Hackett and Gabriel departed, and anything after Waters 'Mr Floyd' left Pink Floyd. Still haunts me after all these years.
Leonard Cohen's "Hallelujah" by J. J. Cale or Jeff Buckley or the original 15 verse composition by Cohen himself which I heard hom perform once.