Okay, I've seen a lot of big fancy fireplaces and there's a gazillion ways to make them but I haven't found a lot of ways to make small, simple fireplaces. However, an idea struck me today, I tested it out, and it works great, so:
1) Chimney, on its side and sunk into the wall
2) Two Roman door frames, back to back to form the mantel and side columns
3) One small cement plate to cover the back wall
4) Brick wall corner to form chimney going up
5) Firepit (unlit) attached to Surface on the back wall of the fireplace, rotated and sunk down slightly, so the logs fit inside
6) The fire itself is one floor torch to provide actual light, and one "torch flame" effect emitter to increase apparent flame size without increasing brightness - I also found that the torch flame emitters, if turned upside down, emit the embers/sparks downward instead of upward so I did that too in order to avoid embers popping out of the fireplace
Below is a 'cutaway' screenshot with the camera angled so you can see what's below the floor, for a better visual on how the logs are placed: