What sold me on Philip Glass was the incredible soundtrack he produced for the Universal horror classic, Dracula (performed by the Kronos Quartet). It's a score which provides the film a sense of longevity Renfield could only long for (the above clip doesn't include Glass' score unfortunately). There's a genuine sense of foreboding when Renfield (a stunning performance by the excellent Dwight Frye) first arrives at Dracula's cobweb riddled, rat infested manse. The scene where Renfield and Dracula first talk and Renfield cuts his finger is accompanied by a score of such sinister intensity; repetition complemented by soft, ebbing strings. There is also a scene where Renfield pleads with Dracula from behind bars not to go to Mina's room that night. The music here again is utterly breathtaking, not so much feeling modern as feeling utterly timeless.
There is nothing cliché about Glass' score. It somehow manages to re-cut the film without leaving a single foot of film on the cutting room floor, offering an entirely different sense of pace to what has gone before and bringing new meaning to a classic.