haunting/dark classical


new to classical, I really like Samuel Barber's Adagio for Strings, Op 11. I am looking for other music with the same dark/haunting sound. Suggestions?
lwatson
I Second Gorecki Symphony #3
Try Also Tchaikovsky Symphony #6 and Shostakovich #7 & #8
Enjoy
I'm very fond of most of what's been recommended and applaud the others for their thoughtful responses. I would like to recommend a piece that won't qualify as Classical music in the usual sense but it is orchestral and most definitely describes what you're are looking for: the sound track of "The DaVinci Code." It's extremely dramatic and dark. The recording is wonderful, too, with unusually good dynamic range and low frequency reproduction.
Schubert's Unfinished Symphony #8 - Get the complete Symphonies box Frans Bruegen and the Age of Enlightment Symphony Orchestra. Mozart's final work - the Clarinet Concerto, he had alot of haunting/dark problems in his life when he wrote this work.
Haunting, dark,classical. Phillip Glass. Dracula, Low, and Heroes. Played by Kronos Quartet.