Old fireplace needs an upgrade

You could paint it a nice color as a pop element in the room or just to add some color. Here are some links with ideas too, like using tile, texturing, etc:

http://www.hgtv.com/remodel/interior-remodel/ways-to-refresh-your-fireplace-on-any-budget-pictures

https://www.kylieminteriors.ca/how-to-update-your-fireplace-5-easy-ideas/

Does it have an opening ,is that a cover?

you could paint it since it blends right into the wall. It's a very odd shape though. Does the thing in the middle remove?

If the insert is cast iron I would strip and restore it... a larger more rustic wood mantle, wider than the fireplace.. the brick could be restored or painted a color that would contrast with the walls (dark grey, black,) or you could install a tile or marble surround and hearth... there are some very nice wood grain or large format tiles (18 in X 36 in ) that look like concrete but are ceramic... and only about $6 a sq. foot. We have a store called "Floor and Decor" here in Phoenix and you can see some of what is available online.

Rather than trying to hide it, I would highlight it-- strip away the paint from the insert and let the original metal-- cast iron?-- stand out. The mantle could be updated with a nice piece of hardwood that can hold some nice family mementos and be a show place for them.

If the insert is cast iron you could strip it and paint it black. A more rustic wood beam as a mantle. I would either cover the brick with an interesting tile, maybe on the hearth area too, something darker than the walls. There are some nice large format tiles (18 in X 36 in for example, but they do come bigger) that look like concrete or Marble... or ones with a pattern... We have a place called Floor and Decor here in Phoenix... and you can see some of the stuff that is available (for ideas) at their website

if it does, you could put fake logs in there with some battery-operated candles. Or, you could get a pretty fireplace screen.

This will definitely be a “non-working” fireplace. Probably by the weekend I’ll be bringing in our gas heater that sits in the middle of it.

I too would strip that old painted tile and the cast iron firebox cover. Then if its not exciting underneath, I would faux paint the tile.... marble, tortoise, etc. and the firebox cover I would do black or a metallic like Rustoleum Metallic comes in lots of colors.... I do like black or grey metallic.

I would paint it a different colorant add a larger mantel,put a large picot over the mantel as well

Looks like it was formerly a coal grate. We have one and I had gas put in with coal. The coal looks real it heats up, glows. and even forms ashes. We love it.The cover is bronze and a lot of them are. I would restore the cover and have someone check the chimney to make sure it is all clear. It needs an entire mantel surround. You can find them on Craigslist and in consignment shops. Sometimes even Habitat which also has granite tile a lot of time. Once the mantel is in surround the opening with granite right over whats there. This would make a beautiful focal point!