One of my favourite sci-fi films for reasons I can't really explain. The music by Tangerine Dream is hypnotic as is their reputation. Scott Glenn is.. well.. Scott Glenn. Movie by Micheal Mann of Miami Vice fame. It's the story line that is the most appealing. Worth a viewing in my personal opinion. I apologize for the quality as it was taken from VHS tape. This movie is hard to find and when I purchase a good copy, I'll upload and replace this one.
From Wikipedia:
The Keep is a 1983 horror film directed by Michael Mann and starring Scott Glenn, Gabriel Byrne, Jürgen Prochnow, Alberta Watson and Ian McKellen. It was released by Paramount Pictures. The story is based on the F. Paul Wilson novel of the same name, originally published in 1981.
enjoy,
Janor