Sides are also brick, it's the width of an actual brick. It was a wood burning fireplace converted to gas I believe (we bought this house).

consider putting the tv in a different location in the room. fireplaces are not a good viewing height for tvs and the heat can be problematic.

if you really want the tv there anyway, an easy solution is wiremold cord mate (or a similar product) to keep the cords hidden. It's not quite as seamless as having nothing, but its waaaay better than hanging wires. When painted it can blend into the decor nicely. I used it in our bedroom where a tv is mounted on the (decorative) fireplace brick and I don't even notice its there.