Tenebrae.

Might seem like a weird answer, considering it's Argento and there are a couple of other movies of his awash in beautiful cinematography and candy colored lighting that'd seem like the more obvious choices, but I really dig the sun-bleached look of the film. Beyond a couple of dark scenes, the movie is saturated in stark bright light, with lots of bland, earth tone interiors. I think I've read before that Argento wanted the film to look like a TV cop show and they pretty much nailed it. Not sure why I find it beautiful, really, since I can totally understand someone else finding it pretty drab and dull, but not me. I love the look of it. I think the shooting locations and the architecture of some of the houses in the film appeal to me as well. Such a neat movie oozing with style.

I get what you mean about the locations and architecture. Particularly the lesbian couple's house where you get a close up view of the exterior with the drawn out crane shot. I don't think you ever see the whole exterior in a single frame, but the way it's presented in the crane shot makes it seem like it has unique, interesting architecture.

I just ordered the Blu-ray of Who Can Kill a Child. I've never seen it and know little about it, so I'm glad to see it got on a list like this. I like movies that are visually pleasing.

I wish there was a Blu-ray of The Reflecting Skin.

The 1979 Dracula has a certain beauty to it, in a steampunky way.

Would any Greenaway count? both cook wife thief lover and zed & two noughts have beautiful cinematography & are meticulously framed. not sure if you would call either horror film tho

heres some more i like visually, a lot have already been mentioned but deserve another shout

a tale of two sisters
alien
audition
bone tomahawk
dont look now
eraserhead
eyes without a face
halloween
hausu
i saw the devil
onibaba
persona
psycho
santa sangre
suspiria
the eyes of my mother
the killing of a sacred deer
the shining

Disturbing Behaviour (1998) is not particularly a great masterpiece of horror, but I think the opening credits are beautiful. It's hard to figure out what you're looking at, it seems like it could be someone exploring a surreal cave... like, a lantern-ish light surrounded by darkness, with occasional flashes of light. I think it is probably supposed to represent a student at the high school's point of view, as they are having the evil brain surgery done, to make him or her into a Stepford Student. But, before you know anything about that, it actually looks kind of beautiful.

Speaking of opening credits, Halloween 4 has a fantastic opening sequence of a rural town on Halloween, with spooky outdoor Halloween decorations in the wind. It's really spooky, and kind of beautiful at times.