I think it looks nice the way it is.

What city are you in? Are there any old mansions or larger homes still with original fixtures in your town? I live near Detroit, where racism and a failing economy meant that our Detroit older homes were not remodeled during the “spiff up” booms in the 70 s, 80s, and 90s. We have tons of original bathrooms from the 1910s -1930s. I love looking at the house listings to see them. Here, bathrooms of that era were tiled with 5x5 to 6x6 inch square tiles. Either to the ceiling around much of the room, or most of the way to the ceiling. A lot have that Art Deco style with black border tiles accentuating architectural features, but even in the plain (more like the craftsman style) homes, square wall tiles with a color theme for each bathroom was the norm. Wall field tiles had a slight variation in color that gave the expanses of tile a beautiful mottled look. Floor tiles were a close match, or had a darker shade of the same color mixed in. The only place I ever saw any subway tiles in an original home here was in a basement laundry and a basement second (summer?) kitchen meant only for servant use. So check more in your area and see if subways were used early in the last century in homes. In Detroit, they were not. Here, colorful square tiles were the norm early in the 1900s. Usually in light shades of greens, blues, peach, pinks, and pearly beige. The MCM tiles here were a bit smaller and their colors were more uniform. Plumbing fixtures early in the century were white. A tone of the wall color was used for tubs, toilets, and sinks in the MCM homes.

I actually have a similar situation- mint green. I have to remove vanity to remove rusted out sink unless a top mount might be an option. I have to remove tub too, so I'm grieving the possible loss of mist of my mint green tile because, as with yours, the vanity is tiled into the wall, and who knows what will happen with tub tile. If it's I will save all I can and polish it cover old terrazzo with loose lay. If top mount sink won't save the day, I'll use a nice pedestal sink and either try to match lower walls with diy paint tile glaze or use ship lap wainscote. I began trying a diy to remove vanity and felt horrible cutting into that wonderful, old tile job. It was impossible to do, and I mangled it badly. Tile is backed with metal lathe. Yours will be too. That said, don't live with this design if you don't like it. Just keep you design in keeping with the period of your home. Please do that. If my tile can't be saved, I'll go with the white walls wood look planks with rivets, pedestal sink or pink ceiling, black and white tile and white vaniGood luck. Don't spend too much unless not an object. Lol.

it's a mixture of lava rock and another type of rock. I'd be more of a fan if it was really tall (and I lived in the mountains) Or, was this cool dark color. (the copper hood and wood slat bench make the space) BTW, you could easily make it look like this. Romabio Masonry lime tinted a brown/black, and a very dark mortar for the joints. (which you could also 'paint') I still like the mortar wash option But, if you want to keep it as is, here's how to spruce up the stone. (Because right now, it's just not nice looking) Clean it w/a good stone cleaner. redo the mortar joints (repipe it ) and then apply an enhancing sealer to the stone. you should get pretty close to this look Looks better w/the appropriate lighting and the wood ceiling. The rock itself isn't anything to leave earth for. it's not some iconic mid century design. It's just something done in the 60's. if you like it great. But if you want to pay homage to more of a mid century look, there are better options. Do a roman brick like mentioned above, or even a glazed brick If it was mine, I'd do something darker like this (stacked brick) Bring in the right design, and this is gorgeous. more of a modern look w/3D tiles and black surround try a basalt or slate tile (I think the darker ones look so much nicer than lava rock) redoing it w/something a bit more linear: And, if you remove the stone, you can restyle it anyway you want. Here are the thinner bricks in a matte black w/a vertical paneling above the natural wood mantle. imagine it w/o your popcorn and the eyeball light and vertical blinds! so much better