If you can’t drywall, one large piece of art would be nice, leave 6+ inches open around it.

keep it simple. Highlight something you treasure.

IMO either drywall or find a fabulous piece of art to fit it does not need to be acanvas could be a sculpture or whatever . I ahte these things that were always put in homes built in a certain era . The only time they work IMO is when you are designing one for a particular piece of art.

Are you leaving the other walls empty? What you did with the other walls might determine what you need to do with the niche.

Wall decor that is 3D would work nicely in this recess.

If you share the dimensions - folks might have some specific ideas

If it gets good light you could try some plants, otherwise just one piece of art would work.

Turn it into bookshelves for volumes you don't need often.

It looks like the niche might be able to accommodate a slim sculpture, framed artwork, or some vases with flowers. See some of the ideas below from various designs of ours.

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