This might be one of those times to paint that inside part an accent color and choose a piece of art that is lower to eye level to truly appreciate. No details in the art as the mantle is still quite high, but do not worry about filling in the area as the eye can only see so much of it anyway.

The piece that is there is lovely, but it is the same shape as the area and it looks small this way. It might work if it was lowered and not centered.

i agree with abbyjean. paint the inside and get some art or a mirror.

At home goods you can buy huge mirrors for very reasonable money. Pick a finish that goes with your room. The bigger the better but don't centre it, it would be nice if you could see yourself in it when you stand before it if the fireplace isn't too tall. But you hours always consider what it will be reflecting.

abbyjean..great advice as usual..

I think it needs dimension & drama...this example is a bit rustic for your application, but it's the same concept...perhaps branches "planted" in a custom "planter" the length & width of the mantle...

https://www.houzz.com/photos/21st-century-bungalow-contemporary-living-room-new-york-phvw-vp~413007

I would have a mirror custom made to fit the inside dimensions, which is not expensive at all, but gives it a custom look, and reflects light.

abbyjean to the rescue again! Look for a contrasting paint that compliments your current wallpaint and paint the niche. The sconces do not say Pottery Barn to me. Lowering the artwork or choosing a new piece that will sit on or just above the mantle would look great. Use some of the photos posted for inspiration :)

You can fill in with trim work by a carpenter in sections, other wise hang something simple and interesting . I like the branches.

art. big art.

A beautiful chandelier would look lovely framed by the tall fireplace. You are on the right idea for artwork but just a little small.

I love all these ideas! I can get another piece and hang them on top of each other to fill more of the space as Mark suggested. I will also paint it if I can stomach climbing on a ladder high enough to reach!

I don't think I would paint it a different color unless you want to accent it.

I did a crude mock-up...don't judge my lack up computer skills. How does it look?

Your computer skills are great and I like how this will look! Maybe hang these two together before deciding about painting the area. I still think painting it will give it the focus it deserves without going overboard in here.

I agree with those that are saying 3D. My parents had a 3D metal sculpture similar to Yorba Linda in Marks comment above. Worked very well. Imo people are too timid and end up with something too small. This is a tough spot but its dramatic so use the drama. I also think OasisDesign has the right idea.

Good luck!

I disagree about painting it another colour, I think it would be to top heavy and that seems dated to me.

I like the idea of painting it, but I see that it could definitely look top heavy with a dark color. If you paint it, a subtle, fairly light color (from the fireplace tile) might be nice.

I would have either a large piece as the one in the first photo posted by Mark or a large painting leaning on the fireplace (similar to Mark's 3rd photo). I don't think you need to paint the area darker.

This is definitely not a do it yourself but it does brighten the room.

Like how a chandelier reflects in a mirror

I create paintings in larger sizes using multiple panels. The panels can be as close or far apart as you like. I am attaching an image of my work. Oh, and I can also incorporate any personal photos into your piece of art:)