I never think the age of the house drives decor and this is a pic of a 1905 House LR where I actually added back trim and original ceiling design . My decor will never be traditional and IMO does not need to be in any home . Your style is what makes it your home. But we need to understand your style and we need to see the whole room

I like your bathroom!

Very cool powder room!

Using marble as a backsplash in your powder room will not be an issue. I have a bathroom that is used every day - the entire countertop is polished marble + has marble backsplash + side splashes. It's been installed for five years - and there are only a couple etching spots (only on the countertop) that no one else sees (except me - and only if I specifically look for them). I've never sealed it since installation - and water still beads up on it. Marble is not as "tender" as many people believe - at least not in a bathroom.

Personally, I think that the fabricator should make you a backsplash after putting holes in your wall that were unnecessary. I am wondering if a brass one might look nice - have it match the brass trim pieces on your vanity? I think the brass would look nice up against the wallpaper.

However, I don't know if the brass on your current vanity is lacquered or unlacquered? or if it will age. I don't know how much work it is to use unlacquered brass due to water splashes. I guess if you just let it age naturally, eventually it will just darken and be fine - however, if lacquered brass was used on the vanity - you'd want the two materials to match.

I assume that the metal that was used for the rest of the vanity won't change due to water splashes - it may be the safer way to go.

A nice piece of marble would be my second choice. I love marble - you'd want to select one that doesn't stand out - it needs to blend. The "star" of this room is the vanity. You've already added in a "co-star" with the wallpaper - I wouldn't add a piece of marble (or any type of material) that would draw someone's eye to the backsplash.

Sorry I am confused the 3 holes I see are for your faucet that I do not see so why not a pice of the same metal as the sink for a backsplash then it will look as if planned,